Source code for django.db.migrations.operations.special

from __future__ import unicode_literals

from django.db import router

from .base import Operation


[docs]class SeparateDatabaseAndState(Operation): """ Takes two lists of operations - ones that will be used for the database, and ones that will be used for the state change. This allows operations that don't support state change to have it applied, or have operations that affect the state or not the database, or so on. """ serialization_expand_args = ['database_operations', 'state_operations'] def __init__(self, database_operations=None, state_operations=None): self.database_operations = database_operations or [] self.state_operations = state_operations or [] def deconstruct(self): kwargs = {} if self.database_operations: kwargs['database_operations'] = self.database_operations if self.state_operations: kwargs['state_operations'] = self.state_operations return ( self.__class__.__name__, [], kwargs ) def state_forwards(self, app_label, state): for state_operation in self.state_operations: state_operation.state_forwards(app_label, state) def database_forwards(self, app_label, schema_editor, from_state, to_state): # We calculate state separately in here since our state functions aren't useful for database_operation in self.database_operations: to_state = from_state.clone() database_operation.state_forwards(app_label, to_state) database_operation.database_forwards(app_label, schema_editor, from_state, to_state) from_state = to_state def database_backwards(self, app_label, schema_editor, from_state, to_state): # We calculate state separately in here since our state functions aren't useful base_state = to_state for pos, database_operation in enumerate(reversed(self.database_operations)): to_state = base_state.clone() for dbop in self.database_operations[:-(pos + 1)]: dbop.state_forwards(app_label, to_state) from_state = to_state.clone() database_operation.state_forwards(app_label, from_state) database_operation.database_backwards(app_label, schema_editor, from_state, to_state) def describe(self): return "Custom state/database change combination"
[docs]class RunSQL(Operation): """ Runs some raw SQL. A reverse SQL statement may be provided. Also accepts a list of operations that represent the state change effected by this SQL change, in case it's custom column/table creation/deletion. """ noop = '' def __init__(self, sql, reverse_sql=None, state_operations=None, hints=None): self.sql = sql self.reverse_sql = reverse_sql self.state_operations = state_operations or [] self.hints = hints or {} def deconstruct(self): kwargs = { 'sql': self.sql, } if self.reverse_sql is not None: kwargs['reverse_sql'] = self.reverse_sql if self.state_operations: kwargs['state_operations'] = self.state_operations if self.hints: kwargs['hints'] = self.hints return ( self.__class__.__name__, [], kwargs ) @property def reversible(self): return self.reverse_sql is not None def state_forwards(self, app_label, state): for state_operation in self.state_operations: state_operation.state_forwards(app_label, state) def database_forwards(self, app_label, schema_editor, from_state, to_state): if router.allow_migrate(schema_editor.connection.alias, app_label, **self.hints): self._run_sql(schema_editor, self.sql) def database_backwards(self, app_label, schema_editor, from_state, to_state): if self.reverse_sql is None: raise NotImplementedError("You cannot reverse this operation") if router.allow_migrate(schema_editor.connection.alias, app_label, **self.hints): self._run_sql(schema_editor, self.reverse_sql) def describe(self): return "Raw SQL operation" def _run_sql(self, schema_editor, sqls): if isinstance(sqls, (list, tuple)): for sql in sqls: params = None if isinstance(sql, (list, tuple)): elements = len(sql) if elements == 2: sql, params = sql else: raise ValueError("Expected a 2-tuple but got %d" % elements) schema_editor.execute(sql, params=params) elif sqls != RunSQL.noop: statements = schema_editor.connection.ops.prepare_sql_script(sqls) for statement in statements: schema_editor.execute(statement, params=None)
[docs]class RunPython(Operation): """ Runs Python code in a context suitable for doing versioned ORM operations. """ reduces_to_sql = False def __init__(self, code, reverse_code=None, atomic=True, hints=None): self.atomic = atomic # Forwards code if not callable(code): raise ValueError("RunPython must be supplied with a callable") self.code = code # Reverse code if reverse_code is None: self.reverse_code = None else: if not callable(reverse_code): raise ValueError("RunPython must be supplied with callable arguments") self.reverse_code = reverse_code self.hints = hints or {} def deconstruct(self): kwargs = { 'code': self.code, } if self.reverse_code is not None: kwargs['reverse_code'] = self.reverse_code if self.atomic is not True: kwargs['atomic'] = self.atomic if self.hints: kwargs['hints'] = self.hints return ( self.__class__.__name__, [], kwargs ) @property def reversible(self): return self.reverse_code is not None def state_forwards(self, app_label, state): # RunPython objects have no state effect. To add some, combine this # with SeparateDatabaseAndState. pass def database_forwards(self, app_label, schema_editor, from_state, to_state): if router.allow_migrate(schema_editor.connection.alias, app_label, **self.hints): # We now execute the Python code in a context that contains a 'models' # object, representing the versioned models as an app registry. # We could try to override the global cache, but then people will still # use direct imports, so we go with a documentation approach instead. self.code(from_state.apps, schema_editor) def database_backwards(self, app_label, schema_editor, from_state, to_state): if self.reverse_code is None: raise NotImplementedError("You cannot reverse this operation") if router.allow_migrate(schema_editor.connection.alias, app_label, **self.hints): self.reverse_code(from_state.apps, schema_editor) def describe(self): return "Raw Python operation" @staticmethod
[docs] def noop(apps, schema_editor): return None
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