magic-removal: Fixed #1133 -- Added ability to use Q objects as args
in DB lookup queries. git-svn-id: http://code.djangoproject.com/svn/django/branches/magic-removal@1884 bcc190cf-cafb-0310-a4f2-bffc1f526a37
This commit is contained in:
Russell Keith-Magee
parent
e9a13940d3
commit
dde6963869
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@ -5,6 +5,7 @@ from django.db.models.query import Q, parse_lookup, fill_table_cache, get_cached
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from django.db.models.query import handle_legacy_orderlist, orderlist2sql, orderfield2column
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from django.dispatch import dispatcher
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from django.db.models import signals
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from django.utils.datastructures import SortedDict
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# Size of each "chunk" for get_iterator calls.
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# Larger values are slightly faster at the expense of more storage space.
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@ -47,7 +48,7 @@ class Manager(object):
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self.creation_counter < klass._default_manager.creation_counter:
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klass._default_manager = self
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def _get_sql_clause(self, **kwargs):
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def _get_sql_clause(self, *args, **kwargs):
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def quote_only_if_word(word):
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if ' ' in word:
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return word
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@ -59,12 +60,28 @@ class Manager(object):
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# Construct the fundamental parts of the query: SELECT X FROM Y WHERE Z.
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select = ["%s.%s" % (backend.quote_name(opts.db_table), backend.quote_name(f.column)) for f in opts.fields]
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tables = (kwargs.get('tables') and [quote_only_if_word(t) for t in kwargs['tables']] or [])
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joins = SortedDict()
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where = kwargs.get('where') and kwargs['where'][:] or []
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params = kwargs.get('params') and kwargs['params'][:] or []
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# Convert all the args into SQL.
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table_count = 0
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for arg in args:
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# check that the provided argument is a Query (i.e., it has a get_sql method)
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if not hasattr(arg, 'get_sql'):
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raise TypeError, "'%s' is not a valid query argument" % str(arg)
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tables2, joins2, where2, params2 = arg.get_sql(opts)
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tables.extend(tables2)
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joins.update(joins2)
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where.extend(where2)
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params.extend(params2)
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# Convert the kwargs into SQL.
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tables2, joins, where2, params2 = parse_lookup(kwargs.items(), opts)
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tables2, joins2, where2, params2 = parse_lookup(kwargs.items(), opts)
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tables.extend(tables2)
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joins.update(joins2)
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where.extend(where2)
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params.extend(params2)
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@ -129,13 +146,13 @@ class Manager(object):
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return select, " ".join(sql), params
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def get_iterator(self, **kwargs):
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def get_iterator(self, *args, **kwargs):
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# kwargs['select'] is a dictionary, and dictionaries' key order is
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# undefined, so we convert it to a list of tuples internally.
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kwargs['select'] = kwargs.get('select', {}).items()
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cursor = connection.cursor()
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select, sql, params = self._get_sql_clause(**kwargs)
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select, sql, params = self._get_sql_clause(*args, **kwargs)
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cursor.execute("SELECT " + (kwargs.get('distinct') and "DISTINCT " or "") + ",".join(select) + sql, params)
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fill_cache = kwargs.get('select_related')
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index_end = len(self.klass._meta.fields)
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@ -152,35 +169,41 @@ class Manager(object):
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setattr(obj, k[0], row[index_end+i])
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yield obj
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def get_list(self, **kwargs):
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return list(self.get_iterator(**kwargs))
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def get_list(self, *args, **kwargs):
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return list(self.get_iterator(*args, **kwargs))
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def get_count(self, **kwargs):
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def get_count(self, *args, **kwargs):
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kwargs['order_by'] = []
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kwargs['offset'] = None
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kwargs['limit'] = None
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kwargs['select_related'] = False
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_, sql, params = self._get_sql_clause(**kwargs)
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_, sql, params = self._get_sql_clause(*args, **kwargs)
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cursor = connection.cursor()
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cursor.execute("SELECT COUNT(*)" + sql, params)
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return cursor.fetchone()[0]
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def get_object(self, **kwargs):
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obj_list = self.get_list(**kwargs)
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def get_object(self, *args, **kwargs):
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obj_list = self.get_list(*args, **kwargs)
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if len(obj_list) < 1:
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raise self.klass.DoesNotExist, "%s does not exist for %s" % (self.klass._meta.object_name, kwargs)
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assert len(obj_list) == 1, "get_object() returned more than one %s -- it returned %s! Lookup parameters were %s" % (self.klass._meta.object_name, len(obj_list), kwargs)
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return obj_list[0]
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def get_in_bulk(self, *args, **kwargs):
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id_list = args and args[0] or kwargs.get('id_list', [])
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assert id_list != [], "get_in_bulk() cannot be passed an empty list."
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# Separate any list arguments: the first list will be used as the id list; subsequent
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# lists will be ignored.
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id_args = filter(lambda arg: isinstance(arg, list), args)
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# Separate any non-list arguments: these are assumed to be query arguments
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sql_args = filter(lambda arg: not isinstance(arg, list), args)
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id_list = id_args and id_args[0] or kwargs.get('id_list', [])
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assert id_list != [], "get_in_bulk() cannot be passed an empty ID list."
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kwargs['where'] = ["%s.%s IN (%s)" % (backend.quote_name(self.klass._meta.db_table), backend.quote_name(self.klass._meta.pk.column), ",".join(['%s'] * len(id_list)))]
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kwargs['params'] = id_list
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obj_list = self.get_list(**kwargs)
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obj_list = self.get_list(*sql_args, **kwargs)
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return dict([(getattr(o, self.klass._meta.pk.attname), o) for o in obj_list])
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def get_values_iterator(self, **kwargs):
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def get_values_iterator(self, *args, **kwargs):
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# select_related and select aren't supported in get_values().
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kwargs['select_related'] = False
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kwargs['select'] = {}
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@ -192,7 +215,7 @@ class Manager(object):
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fields = [f.column for f in self.klass._meta.fields]
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cursor = connection.cursor()
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_, sql, params = self._get_sql_clause(**kwargs)
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_, sql, params = self._get_sql_clause(*args, **kwargs)
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select = ['%s.%s' % (backend.quote_name(self.klass._meta.db_table), backend.quote_name(f)) for f in fields]
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cursor.execute("SELECT " + (kwargs.get('distinct') and "DISTINCT " or "") + ",".join(select) + sql, params)
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while 1:
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@ -202,17 +225,22 @@ class Manager(object):
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for row in rows:
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yield dict(zip(fields, row))
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def get_values(self, **kwargs):
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return list(self.get_values_iterator(**kwargs))
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def get_values(self, *args, **kwargs):
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return list(self.get_values_iterator(*args, **kwargs))
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def __get_latest(self, **kwargs):
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def __get_latest(self, *args, **kwargs):
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kwargs['order_by'] = ('-' + self.klass._meta.get_latest_by,)
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kwargs['limit'] = 1
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return self.get_object(**kwargs)
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return self.get_object(*args, **kwargs)
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def __get_date_list(self, field, *args, **kwargs):
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# Separate any string arguments: the first will be used as the kind
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kind_args = filter(lambda arg: isinstance(arg, str), args)
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# Separate any non-list arguments: these are assumed to be query arguments
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sql_args = filter(lambda arg: not isinstance(arg, str), args)
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from django.db.backends.util import typecast_timestamp
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kind = args and args[0] or kwargs['kind']
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kind = kind_args and kind_args[0] or kwargs.get(['kind'],"")
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assert kind in ("month", "year", "day"), "'kind' must be one of 'year', 'month' or 'day'."
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order = 'ASC'
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if kwargs.has_key('order'):
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@ -223,7 +251,7 @@ class Manager(object):
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if field.null:
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kwargs.setdefault('where', []).append('%s.%s IS NOT NULL' % \
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(backend.quote_name(self.klass._meta.db_table), backend.quote_name(field.column)))
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select, sql, params = self._get_sql_clause(**kwargs)
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select, sql, params = self._get_sql_clause(*sql_args, **kwargs)
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sql = 'SELECT %s %s GROUP BY 1 ORDER BY 1 %s' % \
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(backend.get_date_trunc_sql(kind, '%s.%s' % (backend.quote_name(self.klass._meta.db_table),
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backend.quote_name(field.column))), sql, order)
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@ -198,6 +198,8 @@ def parse_lookup(kwarg_items, opts):
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elif value is None:
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pass
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elif kwarg == 'complex':
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if not hasattr(value, 'get_sql'):
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raise TypeError, "'%s' is not a valid query argument" % str(arg)
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tables2, joins2, where2, params2 = value.get_sql(opts)
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tables.extend(tables2)
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joins.update(joins2)
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@ -224,32 +224,67 @@ OR lookups
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**New in Django development version.**
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By default, multiple lookups are "AND"ed together. If you'd like to use ``OR``
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statements in your queries, use the ``complex`` lookup type.
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By default, keyword argument queries are "AND"ed together. If you have more complex query
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requirements (for example, you need to include an ``OR`` statement in your query), you need
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to use ``Q`` objects.
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``complex`` takes an expression of clauses, each of which is an instance of
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``django.core.meta.Q``. ``Q`` takes an arbitrary number of keyword arguments in
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the standard Django lookup format. And you can use Python's "and" (``&``) and
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"or" (``|``) operators to combine ``Q`` instances. For example::
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A ``Q`` object is an instance of ``django.core.meta.Q``, used to encapsulate a collection of
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keyword arguments. These keyword arguments are specified in the same way as keyword arguments to
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the basic lookup functions like get_object() and get_list(). For example::
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from django.core.meta import Q
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polls.get_object(complex=(Q(question__startswith='Who') | Q(question__startswith='What')))
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Q(question__startswith='What')
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The ``|`` symbol signifies an "OR", so this (roughly) translates into::
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``Q`` objects can be combined using the ``&`` and ``|`` operators. When an operator is used on two
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``Q`` objects, it yields a new ``Q`` object. For example the statement::
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SELECT * FROM polls
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WHERE question LIKE 'Who%' OR question LIKE 'What%';
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Q(question__startswith='Who') | Q(question__startswith='What')
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You can use ``&`` and ``|`` operators together, and use parenthetical grouping.
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Example::
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... yields a single ``Q`` object that represents the "OR" of two "question__startswith" queries, equivalent to the SQL WHERE clause::
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polls.get_object(complex=(Q(question__startswith='Who') & (Q(pub_date__exact=date(2005, 5, 2)) | Q(pub_date__exact=date(2005, 5, 6))))
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... WHERE question LIKE 'Who%' OR question LIKE 'What%'
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This roughly translates into::
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You can compose statements of arbitrary complexity by combining ``Q`` objects with the ``&`` and ``|`` operators. Parenthetical grouping can also be used.
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SELECT * FROM polls
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WHERE question LIKE 'Who%'
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AND (pub_date = '2005-05-02' OR pub_date = '2005-05-06');
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One or more ``Q`` objects can then provided as arguments to the lookup functions. If multiple
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``Q`` object arguments are provided to a lookup function, they will be "AND"ed together.
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For example::
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polls.get_object(
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Q(question__startswith='Who'),
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Q(pub_date__exact=date(2005, 5, 2)) | Q(pub_date__exact=date(2005, 5, 6))
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)
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... roughly translates into the SQL::
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SELECT * from polls WHERE question LIKE 'Who%'
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AND (pub_date = '2005-05-02' OR pub_date = '2005-05-06')
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If necessary, lookup functions can mix the use of ``Q`` objects and keyword arguments. All arguments
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provided to a lookup function (be they keyword argument or ``Q`` object) are "AND"ed together.
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However, if a ``Q`` object is provided, it must precede the definition of any keyword arguments.
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For example::
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polls.get_object(
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Q(pub_date__exact=date(2005, 5, 2)) | Q(pub_date__exact=date(2005, 5, 6)),
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question__startswith='Who')
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... would be a valid query, equivalent to the previous example; but::
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# INVALID QUERY
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polls.get_object(
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question__startswith='Who',
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Q(pub_date__exact=date(2005, 5, 2)) | Q(pub_date__exact=date(2005, 5, 6)))
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... would not be valid.
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A ``Q`` objects can also be provided to the ``complex`` keyword argument. For example::
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polls.get_object(
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complex=Q(question__startswith='Who') &
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(Q(pub_date__exact=date(2005, 5, 2)) |
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Q(pub_date__exact=date(2005, 5, 6))
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)
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)
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See the `OR lookups examples page`_ for more examples.
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@ -68,7 +68,7 @@ Article 4
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>>> Article.objects.get_in_bulk([])
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Traceback (most recent call last):
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...
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AssertionError: get_in_bulk() cannot be passed an empty list.
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AssertionError: get_in_bulk() cannot be passed an empty ID list.
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# get_values() is just like get_list(), except it returns a list of
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# dictionaries instead of object instances -- and you can specify which fields
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@ -3,7 +3,7 @@
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To perform an OR lookup, or a lookup that combines ANDs and ORs, use the
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``complex`` keyword argument, and pass it an expression of clauses using the
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variable ``django.db.models.Q``.
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variable ``django.db.models.Q`` (or any object with a get_sql method).
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"""
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from django.db import models
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@ -54,4 +54,33 @@ API_TESTS = """
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>>> Article.objects.get_list(complex=(Q(pk=1) | Q(pk=2) | Q(pk=3)))
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[Hello, Goodbye, Hello and goodbye]
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# Queries can use Q objects as args
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>>> Article.objects.get_list(Q(headline__startswith='Hello'))
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[Hello, Hello and goodbye]
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# Q arg objects are ANDed
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>>> Article.objects.get_list(Q(headline__startswith='Hello'), Q(headline__contains='bye'))
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[Hello and goodbye]
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# Q arg AND order is irrelevant
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>>> Article.objects.get_list(Q(headline__contains='bye'), headline__startswith='Hello')
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[Hello and goodbye]
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# QOrs are ok, as they ultimately resolve to a Q
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>>> Article.objects.get_list(Q(headline__contains='Hello') | Q(headline__contains='bye'))
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[Hello, Goodbye, Hello and goodbye]
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# Try some arg queries with operations other than get_list
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>>> Article.objects.get_object(Q(headline__startswith='Hello'), Q(headline__contains='bye'))
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Hello and goodbye
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>>> Article.objects.get_count(Q(headline__startswith='Hello') | Q(headline__contains='bye'))
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3
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>>> Article.objects.get_values(Q(headline__startswith='Hello'), Q(headline__contains='bye'))
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[{'headline': 'Hello and goodbye', 'pub_date': datetime.datetime(2005, 11, 29, 0, 0), 'id': 3}]
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>>> Article.objects.get_in_bulk([1,2], Q(headline__startswith='Hello'))
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{1: Hello}
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"""
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