• Language: en

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

from django.db import router

from .base import Operation


[docs]class SeparateDatabaseAndState(Operation): """ Take 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__.__qualname__, [], 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 to_states = {} for dbop in self.database_operations: to_states[dbop] = to_state to_state = to_state.clone() dbop.state_forwards(app_label, to_state) # to_state now has the states of all the database_operations applied # which is the from_state for the backwards migration of the last # operation. for database_operation in reversed(self.database_operations): from_state = to_state to_state = to_states[database_operation] 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): """ Run some raw SQL. A reverse SQL statement may be provided. Also accept 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, elidable=False): self.sql = sql self.reverse_sql = reverse_sql self.state_operations = state_operations or [] self.hints = hints or {} self.elidable = elidable 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__.__qualname__, [], 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): """ Run Python code in a context suitable for doing versioned ORM operations. """ reduces_to_sql = False def __init__(self, code, reverse_code=None, atomic=None, hints=None, elidable=False): 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 {} self.elidable = elidable 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 None: kwargs['atomic'] = self.atomic if self.hints: kwargs['hints'] = self.hints return ( self.__class__.__qualname__, [], 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): # RunPython has access to all models. Ensure that all models are # reloaded in case any are delayed. from_state.clear_delayed_apps_cache() 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"
[docs] @staticmethod def noop(apps, schema_editor): return None
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