django1/django/db/migrations/writer.py

296 lines
11 KiB
Python

from __future__ import unicode_literals
import datetime
import inspect
import decimal
import collections
from importlib import import_module
import os
import types
from django.apps import apps
from django.db import models
from django.db.migrations.loader import MigrationLoader
from django.utils.encoding import force_text
from django.utils.functional import Promise
from django.utils import six
class SettingsReference(str):
"""
Special subclass of string which actually references a current settings
value. It's treated as the value in memory, but serializes out to a
settings.NAME attribute reference.
"""
def __new__(self, value, setting_name):
return str.__new__(self, value)
def __init__(self, value, setting_name):
self.setting_name = setting_name
class OperationWriter(object):
indentation = 2
def __init__(self, operation):
self.operation = operation
self.buff = []
def serialize(self):
imports = set()
name, args, kwargs = self.operation.deconstruct()
argspec = inspect.getargspec(self.operation.__init__)
normalized_kwargs = inspect.getcallargs(self.operation.__init__, *args, **kwargs)
self.feed('migrations.%s(' % name)
self.indent()
for arg_name in argspec.args[1:]:
arg_value = normalized_kwargs[arg_name]
if (arg_name in self.operation.serialization_expand_args and
isinstance(arg_value, (list, tuple, dict))):
if isinstance(arg_value, dict):
self.feed('%s={' % arg_name)
self.indent()
for key, value in arg_value.items():
arg_string, arg_imports = MigrationWriter.serialize(value)
self.feed('%s: %s,' % (repr(key), arg_string))
imports.update(arg_imports)
self.unindent()
self.feed('},')
else:
self.feed('%s=[' % arg_name)
self.indent()
for item in arg_value:
arg_string, arg_imports = MigrationWriter.serialize(item)
self.feed('%s,' % arg_string)
imports.update(arg_imports)
self.unindent()
self.feed('],')
else:
arg_string, arg_imports = MigrationWriter.serialize(arg_value)
self.feed('%s=%s,' % (arg_name, arg_string))
imports.update(arg_imports)
self.unindent()
self.feed('),')
return self.render(), imports
def indent(self):
self.indentation += 1
def unindent(self):
self.indentation -= 1
def feed(self, line):
self.buff.append(' ' * (self.indentation * 4) + line)
def render(self):
return '\n'.join(self.buff)
class MigrationWriter(object):
"""
Takes a Migration instance and is able to produce the contents
of the migration file from it.
"""
def __init__(self, migration):
self.migration = migration
def as_string(self):
"""
Returns a string of the file contents.
"""
items = {
"replaces_str": "",
}
imports = set()
# Deconstruct operations
operations = []
for operation in self.migration.operations:
operation_string, operation_imports = OperationWriter(operation).serialize()
imports.update(operation_imports)
operations.append(operation_string)
items["operations"] = "\n".join(operations) + "\n" if operations else ""
# Format dependencies and write out swappable dependencies right
dependencies = []
for dependency in self.migration.dependencies:
if dependency[0] == "__setting__":
dependencies.append(" migrations.swappable_dependency(settings.%s)," % dependency[1])
imports.add("from django.conf import settings")
else:
dependencies.append(" %s," % repr(dependency))
items["dependencies"] = "\n".join(dependencies) + "\n" if dependencies else ""
# Format imports nicely
imports.discard("from django.db import models")
items["imports"] = "\n".join(imports) + "\n" if imports else ""
# If there's a replaces, make a string for it
if self.migration.replaces:
items['replaces_str'] = "\n replaces = %s\n" % repr(self.migration.replaces)
return (MIGRATION_TEMPLATE % items).encode("utf8")
@property
def filename(self):
return "%s.py" % self.migration.name
@property
def path(self):
migrations_package_name = MigrationLoader.migrations_module(self.migration.app_label)
# See if we can import the migrations module directly
try:
migrations_module = import_module(migrations_package_name)
basedir = os.path.dirname(migrations_module.__file__)
except ImportError:
app_config = apps.get_app_config(self.migration.app_label)
migrations_package_basename = migrations_package_name.split(".")[-1]
# Alright, see if it's a direct submodule of the app
if '%s.%s' % (app_config.name, migrations_package_basename) == migrations_package_name:
basedir = os.path.join(app_config.path, migrations_package_basename)
else:
raise ImportError("Cannot open migrations module %s for app %s" % (migrations_package_name, self.migration.app_label))
return os.path.join(basedir, self.filename)
@classmethod
def serialize_deconstructed(cls, path, args, kwargs):
module, name = path.rsplit(".", 1)
if module == "django.db.models":
imports = set(["from django.db import models"])
name = "models.%s" % name
else:
imports = set(["import %s" % module])
name = path
strings = []
for arg in args:
arg_string, arg_imports = cls.serialize(arg)
strings.append(arg_string)
imports.update(arg_imports)
for kw, arg in kwargs.items():
arg_string, arg_imports = cls.serialize(arg)
imports.update(arg_imports)
strings.append("%s=%s" % (kw, arg_string))
return "%s(%s)" % (name, ", ".join(strings)), imports
@classmethod
def serialize(cls, value):
"""
Serializes the value to a string that's parsable by Python, along
with any needed imports to make that string work.
More advanced than repr() as it can encode things
like datetime.datetime.now.
"""
# Sequences
if isinstance(value, (list, set, tuple)):
imports = set()
strings = []
for item in value:
item_string, item_imports = cls.serialize(item)
imports.update(item_imports)
strings.append(item_string)
if isinstance(value, set):
format = "set([%s])"
elif isinstance(value, tuple):
format = "(%s)" if len(value) > 1 else "(%s,)"
else:
format = "[%s]"
return format % (", ".join(strings)), imports
# Dictionaries
elif isinstance(value, dict):
imports = set()
strings = []
for k, v in value.items():
k_string, k_imports = cls.serialize(k)
v_string, v_imports = cls.serialize(v)
imports.update(k_imports)
imports.update(v_imports)
strings.append((k_string, v_string))
return "{%s}" % (", ".join("%s: %s" % (k, v) for k, v in strings)), imports
# Datetimes
elif isinstance(value, datetime.datetime):
if value.tzinfo is not None:
raise ValueError("Cannot serialize datetime values with timezones. Either use a callable value for default or remove the timezone.")
return repr(value), set(["import datetime"])
# Dates
elif isinstance(value, datetime.date):
return repr(value), set(["import datetime"])
# Settings references
elif isinstance(value, SettingsReference):
return "settings.%s" % value.setting_name, set(["from django.conf import settings"])
# Simple types
elif isinstance(value, six.integer_types + (float, six.binary_type, six.text_type, bool, type(None))):
return repr(value), set()
# Promise
elif isinstance(value, Promise):
return repr(force_text(value)), set()
# Decimal
elif isinstance(value, decimal.Decimal):
return repr(value), set(["from decimal import Decimal"])
# Django fields
elif isinstance(value, models.Field):
attr_name, path, args, kwargs = value.deconstruct()
return cls.serialize_deconstructed(path, args, kwargs)
# Anything that knows how to deconstruct itself.
elif hasattr(value, 'deconstruct'):
return cls.serialize_deconstructed(*value.deconstruct())
# Functions
elif isinstance(value, (types.FunctionType, types.BuiltinFunctionType)):
# @classmethod?
if getattr(value, "__self__", None) and isinstance(value.__self__, type):
klass = value.__self__
module = klass.__module__
return "%s.%s.%s" % (module, klass.__name__, value.__name__), set(["import %s" % module])
elif value.__name__ == '<lambda>':
raise ValueError("Cannot serialize function: lambda")
elif value.__module__ is None:
raise ValueError("Cannot serialize function %r: No module" % value)
else:
module = value.__module__
return "%s.%s" % (module, value.__name__), set(["import %s" % module])
# Classes
elif isinstance(value, type):
special_cases = [
(models.Model, "models.Model", []),
]
for case, string, imports in special_cases:
if case is value:
return string, set(imports)
if hasattr(value, "__module__"):
module = value.__module__
return "%s.%s" % (module, value.__name__), set(["import %s" % module])
# Other iterables
elif isinstance(value, collections.Iterable):
imports = set()
strings = []
for item in value:
item_string, item_imports = cls.serialize(item)
imports.update(item_imports)
strings.append(item_string)
format = "(%s)" if len(strings) > 1 else "(%s,)"
return format % (", ".join(strings)), imports
# Uh oh.
else:
raise ValueError("Cannot serialize: %r\nThere are some values Django cannot serialize into migration files.\nFor more, see https://docs.djangoproject.com/en/dev/topics/migrations/#migration-serializing" % value)
MIGRATION_TEMPLATE = """\
# encoding: utf8
from django.db import models, migrations
%(imports)s
class Migration(migrations.Migration):
%(replaces_str)s
dependencies = [
%(dependencies)s\
]
operations = [
%(operations)s\
]
"""