django1/django/db/migrations/writer.py

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from __future__ import unicode_literals
import os
import re
from importlib import import_module
from django import get_version
from django.apps import apps
from django.db import migrations
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from django.db.migrations.loader import MigrationLoader
from django.db.migrations.serializer import serializer_factory
from django.utils._os import upath
from django.utils.encoding import force_text
from django.utils.inspect import get_func_args
from django.utils.module_loading import module_dir
from django.utils.timezone import now
try:
import enum
except ImportError:
# No support on Python 2 if enum34 isn't installed.
enum = None
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):
def __init__(self, operation, indentation=2):
self.operation = operation
self.buff = []
self.indentation = indentation
def serialize(self):
def _write(_arg_name, _arg_value):
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():
key_string, key_imports = MigrationWriter.serialize(key)
arg_string, arg_imports = MigrationWriter.serialize(value)
args = arg_string.splitlines()
if len(args) > 1:
self.feed('%s: %s' % (key_string, args[0]))
for arg in args[1:-1]:
self.feed(arg)
self.feed('%s,' % args[-1])
else:
self.feed('%s: %s,' % (key_string, arg_string))
imports.update(key_imports)
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)
args = arg_string.splitlines()
if len(args) > 1:
for arg in args[:-1]:
self.feed(arg)
self.feed('%s,' % args[-1])
else:
self.feed('%s,' % arg_string)
imports.update(arg_imports)
self.unindent()
self.feed('],')
else:
arg_string, arg_imports = MigrationWriter.serialize(_arg_value)
args = arg_string.splitlines()
if len(args) > 1:
self.feed('%s=%s' % (_arg_name, args[0]))
for arg in args[1:-1]:
self.feed(arg)
self.feed('%s,' % args[-1])
else:
self.feed('%s=%s,' % (_arg_name, arg_string))
imports.update(arg_imports)
imports = set()
name, args, kwargs = self.operation.deconstruct()
operation_args = get_func_args(self.operation.__init__)
# See if this operation is in django.db.migrations. If it is,
# We can just use the fact we already have that imported,
# otherwise, we need to add an import for the operation class.
if getattr(migrations, name, None) == self.operation.__class__:
self.feed('migrations.%s(' % name)
else:
imports.add('import %s' % (self.operation.__class__.__module__))
self.feed('%s.%s(' % (self.operation.__class__.__module__, name))
self.indent()
for i, arg in enumerate(args):
arg_value = arg
arg_name = operation_args[i]
_write(arg_name, arg_value)
i = len(args)
# Only iterate over remaining arguments
for arg_name in operation_args[i:]:
if arg_name in kwargs: # Don't sort to maintain signature order
arg_value = kwargs[arg_name]
_write(arg_name, arg_value)
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
self.needs_manual_porting = False
def as_string(self):
"""
Returns a string of the file contents.
"""
items = {
"replaces_str": "",
"initial_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:
# No need to output bytestrings for dependencies
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 ""
# Format imports nicely, swapping imports of functions from migration files
# for comments
migration_imports = set()
for line in list(imports):
if re.match("^import (.*)\.\d+[^\s]*$", line):
migration_imports.add(line.split("import")[1].strip())
imports.remove(line)
self.needs_manual_porting = True
# django.db.migrations is always used, but models import may not be.
# If models import exists, merge it with migrations import.
if "from django.db import models" in imports:
imports.discard("from django.db import models")
imports.add("from django.db import migrations, models")
else:
imports.add("from django.db import migrations")
# Sort imports by the package / module to be imported (the part after
# "from" in "from ... import ..." or after "import" in "import ...").
sorted_imports = sorted(imports, key=lambda i: i.split()[1])
items["imports"] = "\n".join(sorted_imports) + "\n" if imports else ""
if migration_imports:
items["imports"] += (
"\n\n# Functions from the following migrations need manual "
"copying.\n# Move them and any dependencies into this file, "
"then update the\n# RunPython operations to refer to the local "
"versions:\n# %s"
) % "\n# ".join(sorted(migration_imports))
# If there's a replaces, make a string for it
if self.migration.replaces:
items['replaces_str'] = "\n replaces = %s\n" % self.serialize(self.migration.replaces)[0]
# Hinting that goes into comment
items.update(
version=get_version(),
timestamp=now().strftime("%Y-%m-%d %H:%M"),
)
if self.migration.initial:
items['initial_str'] = "\n initial = True\n"
return (MIGRATION_TEMPLATE % items).encode("utf8")
@property
def basedir(self):
migrations_package_name = MigrationLoader.migrations_module(self.migration.app_label)
if migrations_package_name is None:
raise ValueError(
"Django can't create migrations for app '%s' because "
"migrations have been disabled via the MIGRATION_MODULES "
"setting." % self.migration.app_label
)
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# See if we can import the migrations module directly
try:
migrations_module = import_module(migrations_package_name)
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except ImportError:
pass
else:
try:
return upath(module_dir(migrations_module))
except ValueError:
pass
# Alright, see if it's a direct submodule of the app
app_config = apps.get_app_config(self.migration.app_label)
maybe_app_name, _, migrations_package_basename = migrations_package_name.rpartition(".")
if app_config.name == maybe_app_name:
return os.path.join(app_config.path, migrations_package_basename)
# In case of using MIGRATION_MODULES setting and the custom package
# doesn't exist, create one, starting from an existing package
existing_dirs, missing_dirs = migrations_package_name.split("."), []
while existing_dirs:
missing_dirs.insert(0, existing_dirs.pop(-1))
try:
base_module = import_module(".".join(existing_dirs))
except ImportError:
continue
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else:
try:
base_dir = upath(module_dir(base_module))
except ValueError:
continue
else:
break
else:
raise ValueError(
"Could not locate an appropriate location to create "
"migrations package %s. Make sure the toplevel "
"package exists and can be imported." %
migrations_package_name)
final_dir = os.path.join(base_dir, *missing_dirs)
if not os.path.isdir(final_dir):
os.makedirs(final_dir)
for missing_dir in missing_dirs:
base_dir = os.path.join(base_dir, missing_dir)
with open(os.path.join(base_dir, "__init__.py"), "w"):
pass
return final_dir
@property
def filename(self):
return "%s.py" % self.migration.name
@property
def path(self):
return os.path.join(self.basedir, self.filename)
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@classmethod
def serialize(cls, value):
return serializer_factory(value).serialize()
MIGRATION_TEMPLATE = """\
# -*- coding: utf-8 -*-
# Generated by Django %(version)s on %(timestamp)s
from __future__ import unicode_literals
%(imports)s
class Migration(migrations.Migration):
%(replaces_str)s%(initial_str)s
dependencies = [
%(dependencies)s\
]
operations = [
%(operations)s\
]
"""