188 lines
7.6 KiB
Python
188 lines
7.6 KiB
Python
from __future__ import unicode_literals
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import datetime
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import types
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import os
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from importlib import import_module
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from django.utils import six
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from django.db import models
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from django.db.models.loading import cache
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from django.db.migrations.loader import MigrationLoader
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from django.utils.encoding import force_text
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from django.utils.functional import Promise
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class MigrationWriter(object):
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"""
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Takes a Migration instance and is able to produce the contents
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of the migration file from it.
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"""
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def __init__(self, migration):
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self.migration = migration
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def as_string(self):
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"""
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Returns a string of the file contents.
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"""
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items = {
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"dependencies": repr(self.migration.dependencies),
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}
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imports = set()
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# Deconstruct operations
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operation_strings = []
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for operation in self.migration.operations:
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name, args, kwargs = operation.deconstruct()
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arg_strings = []
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for arg in args:
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arg_string, arg_imports = self.serialize(arg)
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arg_strings.append(arg_string)
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imports.update(arg_imports)
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for kw, arg in kwargs.items():
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arg_string, arg_imports = self.serialize(arg)
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imports.update(arg_imports)
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arg_strings.append("%s = %s" % (kw, arg_string))
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operation_strings.append("migrations.%s(%s\n )" % (name, "".join("\n %s," % arg for arg in arg_strings)))
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items["operations"] = "[%s\n ]" % "".join("\n %s," % s for s in operation_strings)
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# Format imports nicely
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imports.discard("from django.db import models")
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if not imports:
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items["imports"] = ""
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else:
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items["imports"] = "\n".join(imports) + "\n"
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return (MIGRATION_TEMPLATE % items).encode("utf8")
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@property
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def filename(self):
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return "%s.py" % self.migration.name
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@property
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def path(self):
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migrations_module_name = MigrationLoader.migrations_module(self.migration.app_label)
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app_module = cache.get_app(self.migration.app_label)
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# See if we can import the migrations module directly
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try:
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migrations_module = import_module(migrations_module_name)
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basedir = os.path.dirname(migrations_module.__file__)
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except ImportError:
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# Alright, see if it's a direct submodule of the app
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oneup = ".".join(migrations_module_name.split(".")[:-1])
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app_oneup = ".".join(app_module.__name__.split(".")[:-1])
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if oneup == app_oneup:
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basedir = os.path.join(os.path.dirname(app_module.__file__), migrations_module_name.split(".")[-1])
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else:
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raise ImportError("Cannot open migrations module %s for app %s" % (migrations_module_name, self.migration.app_label))
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return os.path.join(basedir, self.filename)
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@classmethod
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def serialize(cls, value):
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"""
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Serializes the value to a string that's parsable by Python, along
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with any needed imports to make that string work.
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More advanced than repr() as it can encode things
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like datetime.datetime.now.
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"""
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# Sequences
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if isinstance(value, (list, set, tuple)):
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imports = set()
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strings = []
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for item in value:
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item_string, item_imports = cls.serialize(item)
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imports.update(item_imports)
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strings.append(item_string)
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if isinstance(value, set):
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format = "set([%s])"
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elif isinstance(value, tuple):
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format = "(%s,)"
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else:
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format = "[%s]"
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return format % (", ".join(strings)), imports
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# Dictionaries
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elif isinstance(value, dict):
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imports = set()
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strings = []
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for k, v in value.items():
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k_string, k_imports = cls.serialize(k)
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v_string, v_imports = cls.serialize(v)
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imports.update(k_imports)
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imports.update(v_imports)
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strings.append((k_string, v_string))
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return "{%s}" % (", ".join("%s: %s" % (k, v) for k, v in strings)), imports
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# Datetimes
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elif isinstance(value, (datetime.datetime, datetime.date)):
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return repr(value), set(["import datetime"])
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# Simple types
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elif isinstance(value, six.integer_types + (float, six.binary_type, six.text_type, bool, type(None))):
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return repr(value), set()
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# Promise
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elif isinstance(value, Promise):
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return repr(force_text(value)), set()
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# Django fields
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elif isinstance(value, models.Field):
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attr_name, path, args, kwargs = value.deconstruct()
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module, name = path.rsplit(".", 1)
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if module == "django.db.models":
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imports = set(["from django.db import models"])
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name = "models.%s" % name
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else:
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imports = set(["import %s" % module])
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name = path
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arg_strings = []
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for arg in args:
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arg_string, arg_imports = cls.serialize(arg)
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arg_strings.append(arg_string)
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imports.update(arg_imports)
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for kw, arg in kwargs.items():
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arg_string, arg_imports = cls.serialize(arg)
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imports.update(arg_imports)
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arg_strings.append("%s=%s" % (kw, arg_string))
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return "%s(%s)" % (name, ", ".join(arg_strings)), imports
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# Functions
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elif isinstance(value, (types.FunctionType, types.BuiltinFunctionType)):
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# Special-cases, as these don't have im_class
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special_cases = [
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(datetime.datetime.now, "datetime.datetime.now", ["import datetime"]),
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(datetime.datetime.utcnow, "datetime.datetime.utcnow", ["import datetime"]),
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(datetime.date.today, "datetime.date.today", ["import datetime"]),
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]
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for func, string, imports in special_cases:
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if func == value: # For some reason "utcnow is not utcnow"
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return string, set(imports)
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# Method?
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if hasattr(value, "im_class"):
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klass = value.im_class
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module = klass.__module__
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return "%s.%s.%s" % (module, klass.__name__, value.__name__), set(["import %s" % module])
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elif value.__name__ == '<lambda>':
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raise ValueError("Cannot serialize function: lambda")
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elif value.__module__ is None:
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raise ValueError("Cannot serialize function %r: No module" % value)
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else:
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module = value.__module__
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return "%s.%s" % (module, value.__name__), set(["import %s" % module])
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# Classes
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elif isinstance(value, type):
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special_cases = [
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(models.Model, "models.Model", []),
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]
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for case, string, imports in special_cases:
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if case is value:
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return string, set(imports)
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if hasattr(value, "__module__"):
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module = value.__module__
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return "%s.%s" % (module, value.__name__), set(["import %s" % module])
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# Uh oh.
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else:
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raise ValueError("Cannot serialize: %r" % value)
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MIGRATION_TEMPLATE = """# encoding: utf8
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from django.db import models, migrations
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%(imports)s
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class Migration(migrations.Migration):
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dependencies = %(dependencies)s
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operations = %(operations)s
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"""
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