Fixed #23968 -- Replaced list comprehension with generators and dict comprehension

django/contrib/admin/filters.py

@@ -293,8 +293,8 @@ FieldListFilter.register(lambda f: bool(f.choices), ChoicesFieldListFilter)
 class DateFieldListFilter(FieldListFilter):
     def __init__(self, field, request, params, model, model_admin, field_path):
         self.field_generic = '%s__' % field_path
-        self.date_params = dict((k, v) for k, v in params.items()
+        self.date_params = {k: v for k, v in params.items()
-                                if k.startswith(self.field_generic))
+                            if k.startswith(self.field_generic)}
 
         now = timezone.now()
         # When time zone support is enabled, convert "now" to the user's time

django/contrib/contenttypes/management.py

@@ -25,18 +25,18 @@ def update_contenttypes(app_config, verbosity=2, interactive=True, using=DEFAULT
 
     app_label = app_config.label
 
-    app_models = dict(
+    app_models = {
-        (model._meta.model_name, model)
+        model._meta.model_name: model
-        for model in app_config.get_models())
+        for model in app_config.get_models()}
 
     if not app_models:
         return
 
     # Get all the content types
-    content_types = dict(
+    content_types = {
-        (ct.model, ct)
+        ct.model: ct
         for ct in ContentType.objects.using(using).filter(app_label=app_label)
-    )
+    }
     to_remove = [
         ct
         for (model_name, ct) in six.iteritems(content_types)

django/contrib/gis/gdal/field.py

@@ -216,4 +216,4 @@ OGRFieldTypes = {
     10: OFTTime,
     11: OFTDateTime,
 }
-ROGRFieldTypes = dict((cls, num) for num, cls in OGRFieldTypes.items())
+ROGRFieldTypes = {cls: num for num, cls in OGRFieldTypes.items()}

django/contrib/gis/gdal/geomtype.py

@@ -28,7 +28,7 @@ class OGRGeomType(object):
               7 + wkb25bit: 'GeometryCollection25D',
               }
     # Reverse type dictionary, keyed by lower-case of the name.
-    _str_types = dict((v.lower(), k) for k, v in _types.items())
+    _str_types = {v.lower(): k for k, v in _types.items()}
 
     def __init__(self, type_input):
         "Figures out the correct OGR Type based upon the input."

django/contrib/gis/gdal/libgdal.py

@@ -91,7 +91,7 @@ def gdal_version_info():
     m = version_regex.match(ver)
     if not m:
         raise OGRException('Could not parse GDAL version string "%s"' % ver)
-    return dict((key, m.group(key)) for key in ('major', 'minor', 'subminor'))
+    return {key: m.group(key) for key in ('major', 'minor', 'subminor')}
 
 _verinfo = gdal_version_info()
 GDAL_MAJOR_VERSION = int(_verinfo['major'])

django/contrib/gis/geoip/base.py

@@ -48,7 +48,7 @@ class GeoIP(object):
     GEOIP_CHECK_CACHE = 2
     GEOIP_INDEX_CACHE = 4
     GEOIP_MMAP_CACHE = 8
-    cache_options = dict((opt, None) for opt in (0, 1, 2, 4, 8))
+    cache_options = {opt: None for opt in (0, 1, 2, 4, 8)}
 
     # Paths to the city & country binary databases.
     _city_file = ''

django/contrib/gis/geoip/libgeoip.py

@@ -4,9 +4,9 @@ from ctypes.util import find_library
 from django.conf import settings
 
 # Creating the settings dictionary with any settings, if needed.
-GEOIP_SETTINGS = dict((key, getattr(settings, key))
+GEOIP_SETTINGS = {key: getattr(settings, key)
                   for key in ('GEOIP_PATH', 'GEOIP_LIBRARY_PATH', 'GEOIP_COUNTRY', 'GEOIP_CITY')
-                      if hasattr(settings, key))
+                  if hasattr(settings, key)}
 lib_path = GEOIP_SETTINGS.get('GEOIP_LIBRARY_PATH', None)
 
 # The shared library for the GeoIP C API.  May be downloaded

django/contrib/gis/geoip/prototypes.py

@@ -58,7 +58,7 @@ def check_record(result, func, cargs):
         # Checking the pointer to the C structure, if valid pull out elements
         # into a dictionary.
         rec = result.contents
-        record = dict((fld, getattr(rec, fld)) for fld, ctype in rec._fields_)
+        record = {fld: getattr(rec, fld) for fld, ctype in rec._fields_}
 
         # Now converting the strings to unicode using the proper encoding.
         encoding = geoip_encodings[record['charset']]

django/contrib/gis/geometry/test_data.py

@@ -24,7 +24,7 @@ def tuplize(seq):
 
 def strconvert(d):
     "Converts all keys in dictionary to str type."
-    return dict((str(k), v) for k, v in six.iteritems(d))
+    return {str(k): v for k, v in six.iteritems(d)}
 
 
 def get_ds_file(name, ext):

django/contrib/gis/geos/libgeos.py

@@ -145,8 +145,8 @@ def geos_version_info():
     m = version_regex.match(ver)
     if not m:
         raise GEOSException('Could not parse version info string "%s"' % ver)
-    return dict((key, m.group(key)) for key in (
+    return {key: m.group(key) for key in (
-        'version', 'release_candidate', 'capi_version', 'major', 'minor', 'subminor'))
+        'version', 'release_candidate', 'capi_version', 'major', 'minor', 'subminor')}
 
 # Version numbers and whether or not prepared geometry support is available.
 _verinfo = geos_version_info()

django/contrib/gis/management/commands/ogrinspect.py

@@ -90,8 +90,8 @@ class Command(BaseCommand):
         # and options.
         from django.contrib.gis.utils.ogrinspect import _ogrinspect, mapping
         # Filter options to params accepted by `_ogrinspect`
-        ogr_options = dict((k, v) for k, v in options.items()
+        ogr_options = {k: v for k, v in options.items()
-                           if k in inspect.getargspec(_ogrinspect).args and v is not None)
+                       if k in inspect.getargspec(_ogrinspect).args and v is not None}
         output = [s for s in _ogrinspect(ds, model_name, **ogr_options)]
 
         if options['mapping']:
@@ -104,7 +104,7 @@ class Command(BaseCommand):
             mapping_dict = mapping(ds, **kwargs)
             # This extra legwork is so that the dictionary definition comes
             # out in the same order as the fields in the model definition.
-            rev_mapping = dict((v, k) for k, v in mapping_dict.items())
+            rev_mapping = {v: k for k, v in mapping_dict.items()}
             output.extend(['', '# Auto-generated `LayerMapping` dictionary for %s model' % model_name,
                            '%s_mapping = {' % model_name.lower()])
             output.extend("    '%s' : '%s'," % (

django/contrib/gis/measure.py

@@ -295,7 +295,7 @@ class Distance(MeasureBase):
         'Yard (Indian)': 'indian_yd',
         'Yard (Sears)': 'sears_yd'
     }
-    LALIAS = dict((k.lower(), v) for k, v in ALIAS.items())
+    LALIAS = {k.lower(): v for k, v in ALIAS.items()}
 
     def __mul__(self, other):
         if isinstance(other, self.__class__):
@@ -313,9 +313,9 @@ class Distance(MeasureBase):
 class Area(MeasureBase):
     STANDARD_UNIT = AREA_PREFIX + Distance.STANDARD_UNIT
     # Getting the square units values and the alias dictionary.
-    UNITS = dict(('%s%s' % (AREA_PREFIX, k), v ** 2) for k, v in Distance.UNITS.items())
+    UNITS = {'%s%s' % (AREA_PREFIX, k): v ** 2 for k, v in Distance.UNITS.items()}
-    ALIAS = dict((k, '%s%s' % (AREA_PREFIX, v)) for k, v in Distance.ALIAS.items())
+    ALIAS = {k: '%s%s' % (AREA_PREFIX, v) for k, v in Distance.ALIAS.items()}
-    LALIAS = dict((k.lower(), v) for k, v in ALIAS.items())
+    LALIAS = {k.lower(): v for k, v in ALIAS.items()}
 
     def __truediv__(self, other):
         if isinstance(other, NUMERIC_TYPES):

django/contrib/gis/tests/geo3d/tests.py

@@ -38,7 +38,7 @@ city_data = (
 )
 
 # Reference mapping of city name to its altitude (Z value).
-city_dict = dict((name, coords) for name, coords in city_data)
+city_dict = {name: coords for name, coords in city_data}
 
 # 3D freeway data derived from the National Elevation Dataset:
 #  http://seamless.usgs.gov/products/9arc.php

django/contrib/gis/utils/layermapping.py

@@ -329,7 +329,7 @@ class LayerMapping(object):
         if isinstance(self.unique, six.string_types):
             return {self.unique: kwargs[self.unique]}
         else:
-            return dict((fld, kwargs[fld]) for fld in self.unique)
+            return {fld: kwargs[fld] for fld in self.unique}
 
     #### Verification routines used in constructing model keyword arguments. ####
     def verify_ogr_field(self, ogr_field, model_field):

django/contrib/messages/storage/cookie.py

@@ -41,8 +41,8 @@ class MessageDecoder(json.JSONDecoder):
                 return Message(*obj[2:])
             return [self.process_messages(item) for item in obj]
         if isinstance(obj, dict):
-            return dict((key, self.process_messages(value))
+            return {key: self.process_messages(value)
-                        for key, value in six.iteritems(obj))
+                    for key, value in six.iteritems(obj)}
         return obj
 
     def decode(self, s, **kwargs):

django/contrib/messages/tests/base.py

@@ -207,7 +207,7 @@ class BaseTests(object):
         show_url = reverse('show_message')
         messages = []
         for level in ('debug', 'info', 'success', 'warning', 'error'):
-            messages.extend([Message(self.levels[level], msg) for msg in data['messages']])
+            messages.extend(Message(self.levels[level], msg) for msg in data['messages'])
             add_url = reverse('add_message', args=(level,))
             self.client.post(add_url, data)
         response = self.client.get(show_url)

django/contrib/postgres/forms/array.py

@@ -26,7 +26,7 @@ class SimpleArrayField(forms.CharField):
 
     def prepare_value(self, value):
         if isinstance(value, list):
-            return self.delimiter.join([six.text_type(self.base_field.prepare_value(v)) for v in value])
+            return self.delimiter.join(six.text_type(self.base_field.prepare_value(v)) for v in value)
         return value
 
     def to_python(self, value):

django/core/management/__init__.py

@@ -103,9 +103,9 @@ def call_command(name, *args, **options):
     parser = command.create_parser('', name)
     if command.use_argparse:
         # Use the `dest` option name from the parser option
-        opt_mapping = dict((sorted(s_opt.option_strings)[0].lstrip('-').replace('-', '_'), s_opt.dest)
+        opt_mapping = {sorted(s_opt.option_strings)[0].lstrip('-').replace('-', '_'): s_opt.dest
-                           for s_opt in parser._actions if s_opt.option_strings)
+                       for s_opt in parser._actions if s_opt.option_strings}
-        arg_options = dict((opt_mapping.get(key, key), value) for key, value in options.items())
+        arg_options = {opt_mapping.get(key, key): value for key, value in options.items()}
         defaults = parser.parse_args(args=args)
         defaults = dict(defaults._get_kwargs(), **arg_options)
         # Move positional args out of options to mimic legacy optparse
@@ -237,25 +237,25 @@ class ManagementUtility(object):
             # 'key=value' pairs
             if cwords[0] == 'runfcgi':
                 from django.core.servers.fastcgi import FASTCGI_OPTIONS
-                options += [(k, 1) for k in FASTCGI_OPTIONS]
+                options.extend((k, 1) for k in FASTCGI_OPTIONS)
             # special case: add the names of installed apps to options
             elif cwords[0] in ('dumpdata', 'sql', 'sqlall', 'sqlclear',
                     'sqlcustom', 'sqlindexes', 'sqlsequencereset', 'test'):
                 try:
                     app_configs = apps.get_app_configs()
                     # Get the last part of the dotted path as the app name.
-                    options += [(app_config.label, 0) for app_config in app_configs]
+                    options.extend((app_config.label, 0) for app_config in app_configs)
                 except ImportError:
                     # Fail silently if DJANGO_SETTINGS_MODULE isn't set. The
                     # user will find out once they execute the command.
                     pass
             parser = subcommand_cls.create_parser('', cwords[0])
             if subcommand_cls.use_argparse:
-                options += [(sorted(s_opt.option_strings)[0], s_opt.nargs != 0) for s_opt in
+                options.extend((sorted(s_opt.option_strings)[0], s_opt.nargs != 0) for s_opt in
-                            parser._actions if s_opt.option_strings]
+                               parser._actions if s_opt.option_strings)
             else:
-                options += [(s_opt.get_opt_string(), s_opt.nargs) for s_opt in
+                options.extend((s_opt.get_opt_string(), s_opt.nargs) for s_opt in
-                            parser.option_list]
+                               parser.option_list)
             # filter out previously specified options from available options
             prev_opts = [x.split('=')[0] for x in cwords[1:cword - 1]]
             options = [opt for opt in options if opt[0] not in prev_opts]

django/core/management/base.py

@@ -58,7 +58,7 @@ class CommandParser(ArgumentParser):
     def parse_args(self, args=None, namespace=None):
         # Catch missing argument for a better error message
         if (hasattr(self.cmd, 'missing_args_message') and
-                not (args or any([not arg.startswith('-') for arg in args]))):
+                not (args or any(not arg.startswith('-') for arg in args))):
             self.error(self.cmd.missing_args_message)
         return super(CommandParser, self).parse_args(args, namespace)
 

django/core/management/commands/compilemessages.py

@@ -60,7 +60,7 @@ class Command(BaseCommand):
         basedirs = [os.path.join('conf', 'locale'), 'locale']
         if os.environ.get('DJANGO_SETTINGS_MODULE'):
             from django.conf import settings
-            basedirs.extend([upath(path) for path in settings.LOCALE_PATHS])
+            basedirs.extend(upath(path) for path in settings.LOCALE_PATHS)
 
         # Gather existing directories.
         basedirs = set(map(os.path.abspath, filter(os.path.isdir, basedirs)))

django/core/management/commands/diffsettings.py

@@ -3,7 +3,7 @@ from django.core.management.base import BaseCommand
 
 def module_to_dict(module, omittable=lambda k: k.startswith('_')):
     """Converts a module namespace to a Python dictionary."""
-    return dict((k, repr(v)) for k, v in module.__dict__.items() if not omittable(k))
+    return {k: repr(v) for k, v in module.__dict__.items() if not omittable(k)}
 
 
 class Command(BaseCommand):

django/core/management/commands/inspectdb.py

@@ -134,9 +134,9 @@ class Command(BaseCommand):
                     if extra_params:
                         if not field_desc.endswith('('):
                             field_desc += ', '
-                        field_desc += ', '.join([
+                        field_desc += ', '.join(
                             '%s=%s' % (k, strip_prefix(repr(v)))
-                            for k, v in extra_params.items()])
+                            for k, v in extra_params.items())
                     field_desc += ')'
                     if comment_notes:
                         field_desc += '  # ' + ' '.join(comment_notes)

django/core/management/commands/makemigrations.py

@@ -66,10 +66,10 @@ class Command(BaseCommand):
 
         # If app_labels is specified, filter out conflicting migrations for unspecified apps
         if app_labels:
-            conflicts = dict(
+            conflicts = {
-                (app_label, conflict) for app_label, conflict in iteritems(conflicts)
+                app_label: conflict for app_label, conflict in iteritems(conflicts)
                 if app_label in app_labels
-            )
+            }
 
         if conflicts and not self.merge:
             name_str = "; ".join(
@@ -103,10 +103,10 @@ class Command(BaseCommand):
             if not app_labels:
                 raise CommandError("You must supply at least one app label when using --empty.")
             # Make a fake changes() result we can pass to arrange_for_graph
-            changes = dict(
+            changes = {
-                (app, [Migration("custom", app)])
+                app: [Migration("custom", app)]
                 for app in app_labels
-            )
+            }
             changes = autodetector.arrange_for_graph(
                 changes=changes,
                 graph=loader.graph,
@@ -224,7 +224,7 @@ class Command(BaseCommand):
                     for migration in merge_migrations
                 ]
                 try:
-                    biggest_number = max([x for x in numbers if x is not None])
+                    biggest_number = max(x for x in numbers if x is not None)
                 except ValueError:
                     biggest_number = 1
                 subclass = type("Migration", (Migration, ), {

django/core/management/sql.py

@@ -62,8 +62,8 @@ def sql_create(app_config, style, connection):
     if not_installed_models:
         alter_sql = []
         for model in not_installed_models:
-            alter_sql.extend(['-- ' + sql for sql in
+            alter_sql.extend('-- ' + sql for sql in
-                connection.creation.sql_for_pending_references(model, style, pending_references)])
+                connection.creation.sql_for_pending_references(model, style, pending_references))
         if alter_sql:
             final_output.append('-- The following references should be added but depend on non-existent tables:')
             final_output.extend(alter_sql)

django/core/urlresolvers.py

@@ -428,7 +428,7 @@ class RegexURLResolver(LocaleRegexProvider):
         if args and kwargs:
             raise ValueError("Don't mix *args and **kwargs in call to reverse()!")
         text_args = [force_text(v) for v in args]
-        text_kwargs = dict((k, force_text(v)) for (k, v) in kwargs.items())
+        text_kwargs = {k: force_text(v) for (k, v) in kwargs.items()}
 
         if not self._populated:
             self._populate()

django/db/backends/__init__.py

@@ -918,7 +918,7 @@ class BaseDatabaseOperations(object):
         elif params is None:
             u_params = ()
         else:
-            u_params = dict((to_unicode(k), to_unicode(v)) for k, v in params.items())
+            u_params = {to_unicode(k): to_unicode(v) for k, v in params.items()}
 
         return six.text_type("QUERY = %r - PARAMS = %r") % (sql, u_params)
 
@@ -1302,8 +1302,8 @@ class BaseDatabaseIntrospection(object):
         in sorting order between databases.
         """
         def get_names(cursor):
-            return sorted([ti.name for ti in self.get_table_list(cursor)
+            return sorted(ti.name for ti in self.get_table_list(cursor)
-                           if include_views or ti.type == 't'])
+                          if include_views or ti.type == 't')
         if cursor is None:
             with self.connection.cursor() as cursor:
                 return get_names(cursor)

django/db/backends/mysql/introspection.py

@@ -62,7 +62,7 @@ class DatabaseIntrospection(BaseDatabaseIntrospection):
             SELECT column_name, data_type, character_maximum_length, numeric_precision, numeric_scale, extra
             FROM information_schema.columns
             WHERE table_name = %s AND table_schema = DATABASE()""", [table_name])
-        field_info = dict((line[0], InfoLine(*line)) for line in cursor.fetchall())
+        field_info = {line[0]: InfoLine(*line) for line in cursor.fetchall()}
 
         cursor.execute("SELECT * FROM %s LIMIT 1" % self.connection.ops.quote_name(table_name))
         to_int = lambda i: int(i) if i is not None else i
@@ -85,7 +85,7 @@ class DatabaseIntrospection(BaseDatabaseIntrospection):
         Returns a dictionary of {field_name: field_index} for the given table.
         Indexes are 0-based.
         """
-        return dict((d[0], i) for i, d in enumerate(self.get_table_description(cursor, table_name)))
+        return {d[0]: i for i, d in enumerate(self.get_table_description(cursor, table_name))}
 
     def get_relations(self, cursor, table_name):
         """

django/db/backends/oracle/base.py

@@ -886,7 +886,7 @@ class FormatStylePlaceholderCursor(object):
 
     def _format_params(self, params):
         try:
-            return dict((k, OracleParam(v, self, True)) for k, v in params.items())
+            return {k: OracleParam(v, self, True) for k, v in params.items()}
         except AttributeError:
             return tuple(OracleParam(p, self, True) for p in params)
 
@@ -911,7 +911,7 @@ class FormatStylePlaceholderCursor(object):
     def _param_generator(self, params):
         # Try dict handling; if that fails, treat as sequence
         if hasattr(params, 'items'):
-            return dict((k, v.force_bytes) for k, v in params.items())
+            return {k: v.force_bytes for k, v in params.items()}
         else:
             return [p.force_bytes for p in params]
 
@@ -927,7 +927,7 @@ class FormatStylePlaceholderCursor(object):
             query = convert_unicode(query, self.charset)
         elif hasattr(params, 'keys'):
             # Handle params as dict
-            args = dict((k, ":%s" % k) for k in params.keys())
+            args = {k: ":%s" % k for k in params.keys()}
             query = convert_unicode(query % args, self.charset)
         else:
             # Handle params as sequence

django/db/backends/oracle/introspection.py

@@ -74,7 +74,7 @@ class DatabaseIntrospection(BaseDatabaseIntrospection):
         Returns a dictionary of {field_name: field_index} for the given table.
         Indexes are 0-based.
         """
-        return dict((d[0], i) for i, d in enumerate(self.get_table_description(cursor, table_name)))
+        return {d[0]: i for i, d in enumerate(self.get_table_description(cursor, table_name))}
 
     def get_relations(self, cursor, table_name):
         """

django/db/backends/postgresql_psycopg2/introspection.py

@@ -61,7 +61,7 @@ class DatabaseIntrospection(BaseDatabaseIntrospection):
             SELECT column_name, is_nullable, column_default
             FROM information_schema.columns
             WHERE table_name = %s""", [table_name])
-        field_map = dict((line[0], line[1:]) for line in cursor.fetchall())
+        field_map = {line[0]: line[1:] for line in cursor.fetchall()}
         cursor.execute("SELECT * FROM %s LIMIT 1" % self.connection.ops.quote_name(table_name))
         return [FieldInfo(*((force_text(line[0]),) + line[1:6]
                             + (field_map[force_text(line[0])][0] == 'YES', field_map[force_text(line[0])][1])))

django/db/backends/sqlite3/schema.py

@@ -49,10 +49,10 @@ class DatabaseSchemaEditor(BaseDatabaseSchemaEditor):
         Shortcut to transform a model from old_model into new_model
         """
         # Work out the new fields dict / mapping
-        body = dict((f.name, f) for f in model._meta.local_fields)
+        body = {f.name: f for f in model._meta.local_fields}
         # Since mapping might mix column names and default values,
         # its values must be already quoted.
-        mapping = dict((f.column, self.quote_name(f.column)) for f in model._meta.local_fields)
+        mapping = {f.column: self.quote_name(f.column) for f in model._meta.local_fields}
         # This maps field names (not columns) for things like unique_together
         rename_mapping = {}
         # If any of the new or altered fields is introducing a new PK,

django/db/migrations/autodetector.py

@@ -63,10 +63,10 @@ class MigrationAutodetector(object):
         return (
             path,
             [self.deep_deconstruct(value) for value in args],
-            dict(
+            {
-                (key, self.deep_deconstruct(value))
+                key: self.deep_deconstruct(value)
                 for key, value in kwargs.items()
-            ),
+            },
         )
 
     def only_relation_agnostic_fields(self, fields):

django/db/migrations/loader.py

@@ -315,7 +315,7 @@ class MigrationLoader(object):
             if app_label in seen_apps:
                 conflicting_apps.add(app_label)
             seen_apps.setdefault(app_label, set()).add(migration_name)
-        return dict((app_label, seen_apps[app_label]) for app_label in conflicting_apps)
+        return {app_label: seen_apps[app_label] for app_label in conflicting_apps}
 
     def project_state(self, nodes=None, at_end=True):
         """

django/db/migrations/state.py

@@ -35,7 +35,7 @@ class ProjectState(object):
     def clone(self):
         "Returns an exact copy of this ProjectState"
         return ProjectState(
-            models=dict((k, v.clone()) for k, v in self.models.items()),
+            models={k: v.clone() for k, v in self.models.items()},
             real_apps=self.real_apps,
         )
 
@@ -271,10 +271,10 @@ class ModelState(object):
         elif isinstance(value, set):
             return set(cls.force_text_recursive(x) for x in value)
         elif isinstance(value, dict):
-            return dict(
+            return {
-                (cls.force_text_recursive(k), cls.force_text_recursive(v))
+                cls.force_text_recursive(k): cls.force_text_recursive(v)
                 for k, v in value.items()
-            )
+            }
         return value
 
     def construct_fields(self):

django/db/migrations/writer.py

@@ -141,7 +141,7 @@ class MigrationWriter(object):
                 imports.add("from django.conf import settings")
             else:
                 # No need to output bytestrings for dependencies
-                dependency = tuple([force_text(s) for s in dependency])
+                dependency = tuple(force_text(s) for s in dependency)
                 dependencies.append("        %s," % self.serialize(dependency)[0])
         items["dependencies"] = "\n".join(dependencies) + "\n" if dependencies else ""
 

django/db/models/fields/related.py

@@ -405,7 +405,7 @@ class SingleRelatedObjectDescriptor(object):
 
         rel_obj_attr = attrgetter(self.related.field.attname)
         instance_attr = lambda obj: obj._get_pk_val()
-        instances_dict = dict((instance_attr(inst), inst) for inst in instances)
+        instances_dict = {instance_attr(inst): inst for inst in instances}
         query = {'%s__in' % self.related.field.name: instances}
         queryset = queryset.filter(**query)
 
@@ -536,7 +536,7 @@ class ReverseSingleRelatedObjectDescriptor(object):
 
         rel_obj_attr = self.field.get_foreign_related_value
         instance_attr = self.field.get_local_related_value
-        instances_dict = dict((instance_attr(inst), inst) for inst in instances)
+        instances_dict = {instance_attr(inst): inst for inst in instances}
         related_field = self.field.foreign_related_fields[0]
 
         # FIXME: This will need to be revisited when we introduce support for
@@ -570,9 +570,9 @@ class ReverseSingleRelatedObjectDescriptor(object):
             if None in val:
                 rel_obj = None
             else:
-                params = dict(
+                params = {
-                    (rh_field.attname, getattr(instance, lh_field.attname))
+                    rh_field.attname: getattr(instance, lh_field.attname)
-                    for lh_field, rh_field in self.field.related_fields)
+                    for lh_field, rh_field in self.field.related_fields}
                 qs = self.get_queryset(instance=instance)
                 extra_filter = self.field.get_extra_descriptor_filter(instance)
                 if isinstance(extra_filter, dict):
@@ -702,7 +702,7 @@ def create_foreign_related_manager(superclass, rel_field, rel_model):
 
             rel_obj_attr = rel_field.get_local_related_value
             instance_attr = rel_field.get_foreign_related_value
-            instances_dict = dict((instance_attr(inst), inst) for inst in instances)
+            instances_dict = {instance_attr(inst): inst for inst in instances}
             query = {'%s__in' % rel_field.name: instances}
             queryset = queryset.filter(**query)
 
@@ -927,9 +927,9 @@ def create_many_related_manager(superclass, rel):
             join_table = self.through._meta.db_table
             connection = connections[queryset.db]
             qn = connection.ops.quote_name
-            queryset = queryset.extra(select=dict(
+            queryset = queryset.extra(select={
-                ('_prefetch_related_val_%s' % f.attname,
+                '_prefetch_related_val_%s' % f.attname:
-                '%s.%s' % (qn(join_table), qn(f.column))) for f in fk.local_related_fields))
+                '%s.%s' % (qn(join_table), qn(f.column)) for f in fk.local_related_fields})
             return (
                 queryset,
                 lambda result: tuple(

django/db/models/query.py

@@ -491,7 +491,7 @@ class QuerySet(object):
         for f in self.model._meta.fields:
             if f.attname in lookup:
                 lookup[f.name] = lookup.pop(f.attname)
-        params = dict((k, v) for k, v in kwargs.items() if LOOKUP_SEP not in k)
+        params = {k: v for k, v in kwargs.items() if LOOKUP_SEP not in k}
         params.update(defaults)
         return lookup, params
 
@@ -545,7 +545,7 @@ class QuerySet(object):
         if not id_list:
             return {}
         qs = self.filter(pk__in=id_list).order_by()
-        return dict((obj._get_pk_val(), obj) for obj in qs)
+        return {obj._get_pk_val(): obj for obj in qs}
 
     def delete(self):
         """

django/db/models/query_utils.py

@@ -205,7 +205,7 @@ def deferred_class_factory(model, attrs):
             proxy = True
             app_label = model._meta.app_label
 
-        overrides = dict((attr, DeferredAttribute(attr, model)) for attr in attrs)
+        overrides = {attr: DeferredAttribute(attr, model) for attr in attrs}
         overrides["Meta"] = Meta
         overrides["__module__"] = model.__module__
         overrides["_deferred"] = True

django/db/models/sql/query.py

@@ -377,7 +377,7 @@ class Query(object):
             inner_query.select_related = False
             inner_query.related_select_cols = []
 
-            relabels = dict((t, 'subquery') for t in inner_query.tables)
+            relabels = {t: 'subquery' for t in inner_query.tables}
             relabels[None] = 'subquery'
             # Remove any aggregates marked for reduction from the subquery
             # and move them to the outer AggregateQuery.
@@ -390,10 +390,10 @@ class Query(object):
             try:
                 outer_query.add_subquery(inner_query, using)
             except EmptyResultSet:
-                return dict(
+                return {
-                    (alias, None)
+                    alias: None
                     for alias in outer_query.annotation_select
-                )
+                }
         else:
             outer_query = self
             self.select = []
@@ -421,11 +421,11 @@ class Query(object):
                 converters[position] = ([], [annotation.convert_value], annotation.output_field)
         result = compiler.apply_converters(result, converters)
 
-        return dict(
+        return {
-            (alias, val)
+            alias: val
             for (alias, annotation), val
             in zip(outer_query.annotation_select.items(), result)
-        )
+        }
 
     def get_count(self, using):
         """

django/forms/fields.py

@@ -1028,7 +1028,7 @@ class MultiValueField(Field):
 
     def __deepcopy__(self, memo):
         result = super(MultiValueField, self).__deepcopy__(memo)
-        result.fields = tuple([x.__deepcopy__(memo) for x in self.fields])
+        result.fields = tuple(x.__deepcopy__(memo) for x in self.fields)
         return result
 
     def validate(self, value):

django/forms/models.py

@@ -567,7 +567,7 @@ class BaseModelFormSet(BaseFormSet):
 
     def _existing_object(self, pk):
         if not hasattr(self, '_object_dict'):
-            self._object_dict = dict((o.pk, o) for o in self.get_queryset())
+            self._object_dict = {o.pk: o for o in self.get_queryset()}
         return self._object_dict.get(pk)
 
     def _get_to_python(self, field):

django/http/request.py

@@ -458,8 +458,8 @@ class QueryDict(MultiValueDict):
             encode = lambda k, v: urlencode({k: v})
         for k, list_ in self.lists():
             k = force_bytes(k, self.encoding)
-            output.extend([encode(k, force_bytes(v, self.encoding))
+            output.extend(encode(k, force_bytes(v, self.encoding))
-                           for v in list_])
+                          for v in list_)
         return '&'.join(output)
 
 

django/template/base.py

@@ -1058,7 +1058,7 @@ class TagHelperNode(Node):
         resolved_args = [var.resolve(context) for var in self.args]
         if self.takes_context:
             resolved_args = [context] + resolved_args
-        resolved_kwargs = dict((k, v.resolve(context)) for k, v in self.kwargs.items())
+        resolved_kwargs = {k: v.resolve(context) for k, v in self.kwargs.items()}
         return resolved_args, resolved_kwargs
 
 
@@ -1301,9 +1301,9 @@ def get_templatetags_modules():
     Caches the result for faster access.
     """
     templatetags_modules_candidates = ['django.templatetags']
-    templatetags_modules_candidates += [
+    templatetags_modules_candidates.extend(
         '%s.templatetags' % app_config.name
-        for app_config in apps.get_app_configs()]
+        for app_config in apps.get_app_configs())
 
     templatetags_modules = []
     for templatetag_module in templatetags_modules_candidates:

django/template/defaulttags.py

@@ -562,8 +562,8 @@ class WithNode(Node):
         return "<WithNode>"
 
     def render(self, context):
-        values = dict((key, val.resolve(context)) for key, val in
+        values = {key: val.resolve(context) for key, val in
-                      six.iteritems(self.extra_context))
+                  six.iteritems(self.extra_context)}
         with context.push(**values):
             return self.nodelist.render(context)
 

django/template/loader_tags.py

@@ -86,7 +86,7 @@ class ExtendsNode(Node):
         self.nodelist = nodelist
         self.parent_name = parent_name
         self.template_dirs = template_dirs
-        self.blocks = dict((n.name, n) for n in nodelist.get_nodes_by_type(BlockNode))
+        self.blocks = {n.name: n for n in nodelist.get_nodes_by_type(BlockNode)}
 
     def __repr__(self):
         return '<ExtendsNode: extends %s>' % self.parent_name.token
@@ -120,8 +120,8 @@ class ExtendsNode(Node):
             # The ExtendsNode has to be the first non-text node.
             if not isinstance(node, TextNode):
                 if not isinstance(node, ExtendsNode):
-                    blocks = dict((n.name, n) for n in
+                    blocks = {n.name: n for n in
-                                  compiled_parent.nodelist.get_nodes_by_type(BlockNode))
+                              compiled_parent.nodelist.get_nodes_by_type(BlockNode)}
                     block_context.add_blocks(blocks)
                 break
 

django/templatetags/i18n.py

@@ -158,7 +158,7 @@ class BlockTranslateNode(Node):
                 val = default_value % key if '%s' in default_value else default_value
             return render_value_in_context(val, context)
 
-        data = dict((v, render_value(v)) for v in vars)
+        data = {v: render_value(v) for v in vars}
         context.pop()
         try:
             result = result % data

django/test/client.py

@@ -172,19 +172,19 @@ def encode_multipart(boundary, data):
                 if is_file(item):
                     lines.extend(encode_file(boundary, key, item))
                 else:
-                    lines.extend([to_bytes(val) for val in [
+                    lines.extend(to_bytes(val) for val in [
                         '--%s' % boundary,
                         'Content-Disposition: form-data; name="%s"' % key,
                         '',
                         item
-                    ]])
+                    ])
         else:
-            lines.extend([to_bytes(val) for val in [
+            lines.extend(to_bytes(val) for val in [
                 '--%s' % boundary,
                 'Content-Disposition: form-data; name="%s"' % key,
                 '',
                 value
-            ]])
+            ])
 
     lines.extend([
         to_bytes('--%s--' % boundary),

django/test/utils.py

@@ -309,8 +309,8 @@ def compare_xml(want, got):
         return _norm_whitespace_re.sub(' ', v)
 
     def child_text(element):
-        return ''.join([c.data for c in element.childNodes
+        return ''.join(c.data for c in element.childNodes
-                        if c.nodeType == Node.TEXT_NODE])
+                       if c.nodeType == Node.TEXT_NODE)
 
     def children(element):
         return [c for c in element.childNodes

django/utils/datastructures.py

@@ -346,7 +346,7 @@ class MultiValueDict(dict):
 
     def __getstate__(self):
         obj_dict = self.__dict__.copy()
-        obj_dict['_data'] = dict((k, self.getlist(k)) for k in self)
+        obj_dict['_data'] = {k: self.getlist(k) for k in self}
         return obj_dict
 
     def __setstate__(self, obj_dict):
@@ -467,7 +467,7 @@ class MultiValueDict(dict):
         """
         Returns current object as a dict with singular values.
         """
-        return dict((key, self[key]) for key in self)
+        return {key: self[key] for key in self}
 
 
 class ImmutableList(tuple):

django/utils/dateparse.py

@@ -36,7 +36,7 @@ def parse_date(value):
     """
     match = date_re.match(value)
     if match:
-        kw = dict((k, int(v)) for k, v in six.iteritems(match.groupdict()))
+        kw = {k: int(v) for k, v in six.iteritems(match.groupdict())}
         return datetime.date(**kw)
 
 
@@ -54,7 +54,7 @@ def parse_time(value):
         kw = match.groupdict()
         if kw['microsecond']:
             kw['microsecond'] = kw['microsecond'].ljust(6, '0')
-        kw = dict((k, int(v)) for k, v in six.iteritems(kw) if v is not None)
+        kw = {k: int(v) for k, v in six.iteritems(kw) if v is not None}
         return datetime.time(**kw)
 
 
@@ -81,6 +81,6 @@ def parse_datetime(value):
             if tzinfo[0] == '-':
                 offset = -offset
             tzinfo = get_fixed_timezone(offset)
-        kw = dict((k, int(v)) for k, v in six.iteritems(kw) if v is not None)
+        kw = {k: int(v) for k, v in six.iteritems(kw) if v is not None}
         kw['tzinfo'] = tzinfo
         return datetime.datetime(**kw)

django/utils/dictconfig.py

@@ -264,7 +264,7 @@ class BaseConfigurator(object):
             c = self.resolve(c)
         props = config.pop('.', None)
         # Check for valid identifiers
-        kwargs = dict((k, config[k]) for k in config if valid_ident(k))
+        kwargs = {k: config[k] for k in config if valid_ident(k)}
         result = c(**kwargs)
         if props:
             for name, value in props.items():
@@ -502,7 +502,7 @@ class DictConfigurator(BaseConfigurator):
                 'address' in config:
                 config['address'] = self.as_tuple(config['address'])
             factory = klass
-        kwargs = dict((k, config[k]) for k in config if valid_ident(k))
+        kwargs = {k: config[k] for k in config if valid_ident(k)}
         try:
             result = factory(**kwargs)
         except TypeError as te:

django/utils/encoding.py

@@ -105,8 +105,8 @@ def force_text(s, encoding='utf-8', strings_only=False, errors='strict'):
             # working unicode method. Try to handle this without raising a
             # further exception by individually forcing the exception args
             # to unicode.
-            s = ' '.join([force_text(arg, encoding, strings_only,
+            s = ' '.join(force_text(arg, encoding, strings_only, errors)
-                    errors) for arg in s])
+                         for arg in s)
     return s
 
 
@@ -152,8 +152,8 @@ def force_bytes(s, encoding='utf-8', strings_only=False, errors='strict'):
                 # An Exception subclass containing non-ASCII data that doesn't
                 # know how to print itself properly. We shouldn't raise a
                 # further exception.
-                return b' '.join([force_bytes(arg, encoding, strings_only,
+                return b' '.join(force_bytes(arg, encoding, strings_only, errors)
-                        errors) for arg in s])
+                                 for arg in s)
             return six.text_type(s).encode(encoding, errors)
     else:
         return s.encode(encoding, errors)

django/utils/html.py

@@ -90,7 +90,7 @@ def format_html(format_string, *args, **kwargs):
     of str.format or % interpolation to build up small HTML fragments.
     """
     args_safe = map(conditional_escape, args)
-    kwargs_safe = dict((k, conditional_escape(v)) for (k, v) in six.iteritems(kwargs))
+    kwargs_safe = {k: conditional_escape(v) for (k, v) in six.iteritems(kwargs)}
     return mark_safe(format_string.format(*args_safe, **kwargs_safe))
 
 

django/utils/termcolors.py

@@ -5,8 +5,8 @@ termcolors.py
 from django.utils import six
 
 color_names = ('black', 'red', 'green', 'yellow', 'blue', 'magenta', 'cyan', 'white')
-foreground = dict((color_names[x], '3%s' % x) for x in range(8))
+foreground = {color_names[x]: '3%s' % x for x in range(8)}
-background = dict((color_names[x], '4%s' % x) for x in range(8))
+background = {color_names[x]: '4%s' % x for x in range(8)}
 
 RESET = '0'
 opt_dict = {'bold': '1', 'underscore': '4', 'blink': '5', 'reverse': '7', 'conceal': '8'}

django/utils/tree.py

@@ -43,10 +43,10 @@ class Node(object):
 
     def __str__(self):
         if self.negated:
-            return '(NOT (%s: %s))' % (self.connector, ', '.join([str(c) for c
+            return '(NOT (%s: %s))' % (self.connector, ', '.join(str(c) for c
-                    in self.children]))
+                    in self.children))
-        return '(%s: %s)' % (self.connector, ', '.join([str(c) for c in
+        return '(%s: %s)' % (self.connector, ', '.join(str(c) for c in
-                self.children]))
+                self.children))
 
     def __repr__(self):
         return "<%s: %s>" % (self.__class__.__name__, self)

django/views/debug.py

@@ -59,7 +59,7 @@ def cleanse_setting(key, value):
             cleansed = CLEANSED_SUBSTITUTE
         else:
             if isinstance(value, dict):
-                cleansed = dict((k, cleanse_setting(k, v)) for k, v in value.items())
+                cleansed = {k: cleanse_setting(k, v) for k, v in value.items()}
             else:
                 cleansed = value
     except TypeError:

docs/_ext/applyxrefs.py

@@ -53,7 +53,7 @@ def main(argv=None):
     files = []
     for root in argv[1:]:
         for (dirpath, dirnames, filenames) in os.walk(root):
-            files.extend([(dirpath, f) for f in filenames])
+            files.extend((dirpath, f) for f in filenames)
     files.sort()
     files = [os.path.join(p, fn) for p, fn in files if fn.endswith('.txt')]
     #print files

docs/_ext/literals_to_xrefs.py

@@ -145,8 +145,8 @@ def colorize(text='', opts=(), **kwargs):
         print('this should not be red')
     """
     color_names = ('black', 'red', 'green', 'yellow', 'blue', 'magenta', 'cyan', 'white')
-    foreground = dict([(color_names[x], '3%s' % x) for x in range(8)])
+    foreground = {color_names[x]: '3%s' % x for x in range(8)}
-    background = dict([(color_names[x], '4%s' % x) for x in range(8)])
+    background = {color_names[x]: '4%s' % x for x in range(8)}
 
     RESET = '0'
     opt_dict = {'bold': '1', 'underscore': '4', 'blink': '5', 'reverse': '7', 'conceal': '8'}

docs/ref/models/querysets.txt

@@ -882,8 +882,8 @@ For example, suppose you have these models::
         toppings = models.ManyToManyField(Topping)
 
         def __str__(self):              # __unicode__ on Python 2
-            return "%s (%s)" % (self.name, ", ".join([topping.name
+            return "%s (%s)" % (self.name, ", ".join(topping.name
-                                                      for topping in self.toppings.all()]))
+                                                     for topping in self.toppings.all()))
 
 and run::
 
@@ -1600,7 +1600,7 @@ found, ``get_or_create()`` will instantiate and save a new object, returning a
 tuple of the new object and ``True``. The new object will be created roughly
 according to this algorithm::
 
-    params = dict([(k, v) for k, v in kwargs.items() if '__' not in k])
+    params = {k: v for k, v in kwargs.items() if '__' not in k}
     params.update(defaults)
     obj = self.model(**params)
     obj.save()

tests/cache/tests.py

@@ -219,7 +219,7 @@ def caches_setting_for_tests(base=None, **params):
     # This results in the following search order:
     # params -> _caches_setting_base -> base
     base = base or {}
-    setting = dict((k, base.copy()) for k in _caches_setting_base.keys())
+    setting = {k: base.copy() for k in _caches_setting_base.keys()}
     for key, cache_params in setting.items():
         cache_params.update(_caches_setting_base[key])
         cache_params.update(params)

tests/file_uploads/views.py

@@ -92,7 +92,7 @@ def file_upload_echo(request):
     """
     Simple view to echo back info about uploaded files for tests.
     """
-    r = dict((k, f.name) for k, f in request.FILES.items())
+    r = {k: f.name for k, f in request.FILES.items()}
     return HttpResponse(json.dumps(r))
 
 
@@ -100,7 +100,7 @@ def file_upload_echo_content(request):
     """
     Simple view to echo back the content of uploaded files for tests.
     """
-    r = dict((k, f.read().decode('utf-8')) for k, f in request.FILES.items())
+    r = {k: f.read().decode('utf-8') for k, f in request.FILES.items()}
     return HttpResponse(json.dumps(r))
 
 
@@ -153,9 +153,9 @@ def file_upload_content_type_extra(request):
     """
     params = {}
     for file_name, uploadedfile in request.FILES.items():
-        params[file_name] = dict([
+        params[file_name] = {
-            (k, smart_str(v)) for k, v in uploadedfile.content_type_extra.items()
+            k: smart_str(v) for k, v in uploadedfile.content_type_extra.items()
-        ])
+        }
     return HttpResponse(json.dumps(params))
 
 

tests/model_formsets_regress/tests.py

@@ -438,10 +438,10 @@ class FormfieldShouldDeleteFormTests(TestCase):
         # pass standard data dict & see none updated
         data = dict(self.data)
         data['form-INITIAL_FORMS'] = 4
-        data.update(dict(
+        data.update({
-            ('form-%d-id' % i, user.pk)
+            'form-%d-id' % i: user.pk
             for i, user in enumerate(User.objects.all())
-        ))
+        })
         formset = self.NormalFormset(data, queryset=User.objects.all())
         self.assertTrue(formset.is_valid())
         self.assertEqual(len(formset.save()), 0)
@@ -455,10 +455,10 @@ class FormfieldShouldDeleteFormTests(TestCase):
         # create data dict with all fields marked for deletion
         data = dict(self.data)
         data['form-INITIAL_FORMS'] = 4
-        data.update(dict(
+        data.update({
-            ('form-%d-id' % i, user.pk)
+            'form-%d-id' % i: user.pk
             for i, user in enumerate(User.objects.all())
-        ))
+        })
         data.update(self.delete_all_ids)
         formset = self.NormalFormset(data, queryset=User.objects.all())
         self.assertTrue(formset.is_valid())
@@ -474,10 +474,10 @@ class FormfieldShouldDeleteFormTests(TestCase):
         # create data dict with all fields marked for deletion
         data = dict(self.data)
         data['form-INITIAL_FORMS'] = 4
-        data.update(dict(
+        data.update({
-            ('form-%d-id' % i, user.pk)
+            'form-%d-id' % i: user.pk
             for i, user in enumerate(User.objects.all())
-        ))
+        })
         data.update(self.delete_all_ids)
         formset = self.DeleteFormset(data, queryset=User.objects.all())
 

tests/model_meta/test.py

@@ -497,10 +497,10 @@ TEST_RESULTS = {
 class OptionsBaseTests(test.TestCase):
 
     def _map_rq_names(self, res):
-        return tuple([(o.field.related_query_name(), m) for o, m in res])
+        return tuple((o.field.related_query_name(), m) for o, m in res)
 
     def _map_names(self, res):
-        return tuple([(f.name, m) for f, m in res])
+        return tuple((f.name, m) for f, m in res)
 
 
 class DataTests(OptionsBaseTests):

tests/prefetch_related/tests.py

@@ -653,9 +653,9 @@ class DefaultManagerTests(TestCase):
             # the default manager on teachers to immediately get all the related
             # qualifications, since this will do one query per teacher.
             qs = Department.objects.prefetch_related('teachers')
-            depts = "".join(["%s department: %s\n" %
+            depts = "".join("%s department: %s\n" %
                             (dept.name, ", ".join(six.text_type(t) for t in dept.teachers.all()))
-                             for dept in qs])
+                            for dept in qs)
 
             self.assertEqual(depts,
                              "English department: Mr Cleese (BA, BSci, MA, PhD), Mr Idle (BA)\n"
@@ -990,9 +990,9 @@ class MultiDbTests(TestCase):
         # Forward
         qs1 = B.prefetch_related('authors')
         with self.assertNumQueries(2, using='other'):
-            books = "".join(["%s (%s)\n" %
+            books = "".join("%s (%s)\n" %
                             (book.title, ", ".join(a.name for a in book.authors.all()))
-                             for book in qs1])
+                            for book in qs1)
         self.assertEqual(books,
                          "Poems (Charlotte, Anne, Emily)\n"
                          "Jane Eyre (Charlotte)\n"
@@ -1002,9 +1002,9 @@ class MultiDbTests(TestCase):
         # Reverse
         qs2 = A.prefetch_related('books')
         with self.assertNumQueries(2, using='other'):
-            authors = "".join(["%s: %s\n" %
+            authors = "".join("%s: %s\n" %
                               (author.name, ", ".join(b.title for b in author.books.all()))
-                               for author in qs2])
+                              for author in qs2)
         self.assertEqual(authors,
                          "Charlotte: Poems, Jane Eyre\n"
                          "Anne: Poems\n"

tests/schema/tests.py

@@ -64,13 +64,13 @@ class SchemaTests(TransactionTestCase):
 
     def column_classes(self, model):
         with connection.cursor() as cursor:
-            columns = dict(
+            columns = {
-                (d[0], (connection.introspection.get_field_type(d[1], d), d))
+                d[0]: (connection.introspection.get_field_type(d[1], d), d)
                 for d in connection.introspection.get_table_description(
                     cursor,
                     model._meta.db_table,
                 )
-            )
+            }
         # SQLite has a different format for field_type
         for name, (type, desc) in columns.items():
             if isinstance(type, tuple):