Ajoutez des fichiers projet.

venv/Lib/site-packages/django/db/migrations/migration.py

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+from django.db.migrations.utils import get_migration_name_timestamp
+from django.db.transaction import atomic
+
+from .exceptions import IrreversibleError
+
+
+class Migration:
+    """
+    The base class for all migrations.
+
+    Migration files will import this from django.db.migrations.Migration
+    and subclass it as a class called Migration. It will have one or more
+    of the following attributes:
+
+     - operations: A list of Operation instances, probably from django.db.migrations.operations
+     - dependencies: A list of tuples of (app_path, migration_name)
+     - run_before: A list of tuples of (app_path, migration_name)
+     - replaces: A list of migration_names
+
+    Note that all migrations come out of migrations and into the Loader or
+    Graph as instances, having been initialized with their app label and name.
+    """
+
+    # Operations to apply during this migration, in order.
+    operations = []
+
+    # Other migrations that should be run before this migration.
+    # Should be a list of (app, migration_name).
+    dependencies = []
+
+    # Other migrations that should be run after this one (i.e. have
+    # this migration added to their dependencies). Useful to make third-party
+    # apps' migrations run after your AUTH_USER replacement, for example.
+    run_before = []
+
+    # Migration names in this app that this migration replaces. If this is
+    # non-empty, this migration will only be applied if all these migrations
+    # are not applied.
+    replaces = []
+
+    # Is this an initial migration? Initial migrations are skipped on
+    # --fake-initial if the table or fields already exist. If None, check if
+    # the migration has any dependencies to determine if there are dependencies
+    # to tell if db introspection needs to be done. If True, always perform
+    # introspection. If False, never perform introspection.
+    initial = None
+
+    # Whether to wrap the whole migration in a transaction. Only has an effect
+    # on database backends which support transactional DDL.
+    atomic = True
+
+    def __init__(self, name, app_label):
+        self.name = name
+        self.app_label = app_label
+        # Copy dependencies & other attrs as we might mutate them at runtime
+        self.operations = list(self.__class__.operations)
+        self.dependencies = list(self.__class__.dependencies)
+        self.run_before = list(self.__class__.run_before)
+        self.replaces = list(self.__class__.replaces)
+
+    def __eq__(self, other):
+        return (
+            isinstance(other, Migration) and
+            self.name == other.name and
+            self.app_label == other.app_label
+        )
+
+    def __repr__(self):
+        return "<Migration %s.%s>" % (self.app_label, self.name)
+
+    def __str__(self):
+        return "%s.%s" % (self.app_label, self.name)
+
+    def __hash__(self):
+        return hash("%s.%s" % (self.app_label, self.name))
+
+    def mutate_state(self, project_state, preserve=True):
+        """
+        Take a ProjectState and return a new one with the migration's
+        operations applied to it. Preserve the original object state by
+        default and return a mutated state from a copy.
+        """
+        new_state = project_state
+        if preserve:
+            new_state = project_state.clone()
+
+        for operation in self.operations:
+            operation.state_forwards(self.app_label, new_state)
+        return new_state
+
+    def apply(self, project_state, schema_editor, collect_sql=False):
+        """
+        Take a project_state representing all migrations prior to this one
+        and a schema_editor for a live database and apply the migration
+        in a forwards order.
+
+        Return the resulting project state for efficient reuse by following
+        Migrations.
+        """
+        for operation in self.operations:
+            # If this operation cannot be represented as SQL, place a comment
+            # there instead
+            if collect_sql:
+                schema_editor.collected_sql.append("--")
+                if not operation.reduces_to_sql:
+                    schema_editor.collected_sql.append(
+                        "-- MIGRATION NOW PERFORMS OPERATION THAT CANNOT BE WRITTEN AS SQL:"
+                    )
+                schema_editor.collected_sql.append("-- %s" % operation.describe())
+                schema_editor.collected_sql.append("--")
+                if not operation.reduces_to_sql:
+                    continue
+            # Save the state before the operation has run
+            old_state = project_state.clone()
+            operation.state_forwards(self.app_label, project_state)
+            # Run the operation
+            atomic_operation = operation.atomic or (self.atomic and operation.atomic is not False)
+            if not schema_editor.atomic_migration and atomic_operation:
+                # Force a transaction on a non-transactional-DDL backend or an
+                # atomic operation inside a non-atomic migration.
+                with atomic(schema_editor.connection.alias):
+                    operation.database_forwards(self.app_label, schema_editor, old_state, project_state)
+            else:
+                # Normal behaviour
+                operation.database_forwards(self.app_label, schema_editor, old_state, project_state)
+        return project_state
+
+    def unapply(self, project_state, schema_editor, collect_sql=False):
+        """
+        Take a project_state representing all migrations prior to this one
+        and a schema_editor for a live database and apply the migration
+        in a reverse order.
+
+        The backwards migration process consists of two phases:
+
+        1. The intermediate states from right before the first until right
+           after the last operation inside this migration are preserved.
+        2. The operations are applied in reverse order using the states
+           recorded in step 1.
+        """
+        # Construct all the intermediate states we need for a reverse migration
+        to_run = []
+        new_state = project_state
+        # Phase 1
+        for operation in self.operations:
+            # If it's irreversible, error out
+            if not operation.reversible:
+                raise IrreversibleError("Operation %s in %s is not reversible" % (operation, self))
+            # Preserve new state from previous run to not tamper the same state
+            # over all operations
+            new_state = new_state.clone()
+            old_state = new_state.clone()
+            operation.state_forwards(self.app_label, new_state)
+            to_run.insert(0, (operation, old_state, new_state))
+
+        # Phase 2
+        for operation, to_state, from_state in to_run:
+            if collect_sql:
+                schema_editor.collected_sql.append("--")
+                if not operation.reduces_to_sql:
+                    schema_editor.collected_sql.append(
+                        "-- MIGRATION NOW PERFORMS OPERATION THAT CANNOT BE WRITTEN AS SQL:"
+                    )
+                schema_editor.collected_sql.append("-- %s" % operation.describe())
+                schema_editor.collected_sql.append("--")
+                if not operation.reduces_to_sql:
+                    continue
+            atomic_operation = operation.atomic or (self.atomic and operation.atomic is not False)
+            if not schema_editor.atomic_migration and atomic_operation:
+                # Force a transaction on a non-transactional-DDL backend or an
+                # atomic operation inside a non-atomic migration.
+                with atomic(schema_editor.connection.alias):
+                    operation.database_backwards(self.app_label, schema_editor, from_state, to_state)
+            else:
+                # Normal behaviour
+                operation.database_backwards(self.app_label, schema_editor, from_state, to_state)
+        return project_state
+
+    def suggest_name(self):
+        """
+        Suggest a name for the operations this migration might represent. Names
+        are not guaranteed to be unique, but put some effort into the fallback
+        name to avoid VCS conflicts if possible.
+        """
+        if self.initial:
+            return 'initial'
+
+        raw_fragments = [op.migration_name_fragment for op in self.operations]
+        fragments = [name for name in raw_fragments if name]
+
+        if not fragments or len(fragments) != len(self.operations):
+            return 'auto_%s' % get_migration_name_timestamp()
+
+        name = fragments[0]
+        for fragment in fragments[1:]:
+            new_name = f'{name}_{fragment}'
+            if len(new_name) > 52:
+                name = f'{name}_and_more'
+                break
+            name = new_name
+        return name
+
+
+class SwappableTuple(tuple):
+    """
+    Subclass of tuple so Django can tell this was originally a swappable
+    dependency when it reads the migration file.
+    """
+
+    def __new__(cls, value, setting):
+        self = tuple.__new__(cls, value)
+        self.setting = setting
+        return self
+
+
+def swappable_dependency(value):
+    """Turn a setting value into a dependency."""
+    return SwappableTuple((value.split(".", 1)[0], "__first__"), value)