diff options
Diffstat (limited to 'lib/sqlalchemy/ext/automap.py')
| -rw-r--r-- | lib/sqlalchemy/ext/automap.py | 46 |
1 files changed, 40 insertions, 6 deletions
diff --git a/lib/sqlalchemy/ext/automap.py b/lib/sqlalchemy/ext/automap.py index 121285ab3..c11795d37 100644 --- a/lib/sqlalchemy/ext/automap.py +++ b/lib/sqlalchemy/ext/automap.py @@ -243,7 +243,26 @@ follows: one-to-many backref will be created on the referred class referring to this class. -4. The names of the relationships are determined using the +4. If any of the columns that are part of the :class:`.ForeignKeyConstraint` + are not nullable (e.g. ``nullable=False``), a + :paramref:`~.relationship.cascade` keyword argument + of ``all, delete-orphan`` will be added to the keyword arguments to + be passed to the relationship or backref. If the + :class:`.ForeignKeyConstraint` reports that + :paramref:`.ForeignKeyConstraint.ondelete` + is set to ``CASCADE`` for a not null or ``SET NULL`` for a nullable + set of columns, the option :paramref:`~.relationship.passive_deletes` + flag is set to ``True`` in the set of relationship keyword arguments. + Note that not all backends support reflection of ON DELETE. + + .. versionadded:: 1.0.0 - automap will detect non-nullable foreign key + constraints when producing a one-to-many relationship and establish + a default cascade of ``all, delete-orphan`` if so; additionally, + if the constraint specifies :paramref:`.ForeignKeyConstraint.ondelete` + of ``CASCADE`` for non-nullable or ``SET NULL`` for nullable columns, + the ``passive_deletes=True`` option is also added. + +5. The names of the relationships are determined using the :paramref:`.AutomapBase.prepare.name_for_scalar_relationship` and :paramref:`.AutomapBase.prepare.name_for_collection_relationship` callable functions. It is important to note that the default relationship @@ -252,18 +271,18 @@ follows: alternate class naming scheme, that's the name from which the relationship name will be derived. -5. The classes are inspected for an existing mapped property matching these +6. The classes are inspected for an existing mapped property matching these names. If one is detected on one side, but none on the other side, :class:`.AutomapBase` attempts to create a relationship on the missing side, then uses the :paramref:`.relationship.back_populates` parameter in order to point the new relationship to the other side. -6. In the usual case where no relationship is on either side, +7. In the usual case where no relationship is on either side, :meth:`.AutomapBase.prepare` produces a :func:`.relationship` on the "many-to-one" side and matches it to the other using the :paramref:`.relationship.backref` parameter. -7. Production of the :func:`.relationship` and optionally the :func:`.backref` +8. Production of the :func:`.relationship` and optionally the :func:`.backref` is handed off to the :paramref:`.AutomapBase.prepare.generate_relationship` function, which can be supplied by the end-user in order to augment the arguments passed to :func:`.relationship` or :func:`.backref` or to @@ -877,6 +896,19 @@ def _relationships_for_fks(automap_base, map_config, table_to_map_config, constraint ) + o2m_kws = {} + nullable = False not in set([fk.parent.nullable for fk in fks]) + if not nullable: + o2m_kws['cascade'] = "all, delete-orphan" + + if constraint.ondelete and \ + constraint.ondelete.lower() == "cascade": + o2m_kws['passive_deletes'] = True + else: + if constraint.ondelete and \ + constraint.ondelete.lower() == "set null": + o2m_kws['passive_deletes'] = True + create_backref = backref_name not in referred_cfg.properties if relationship_name not in map_config.properties: @@ -885,7 +917,8 @@ def _relationships_for_fks(automap_base, map_config, table_to_map_config, automap_base, interfaces.ONETOMANY, backref, backref_name, referred_cls, local_cls, - collection_class=collection_class) + collection_class=collection_class, + **o2m_kws) else: backref_obj = None rel = generate_relationship(automap_base, @@ -916,7 +949,8 @@ def _relationships_for_fks(automap_base, map_config, table_to_map_config, fk.parent for fk in constraint.elements], back_populates=relationship_name, - collection_class=collection_class) + collection_class=collection_class, + **o2m_kws) if rel is not None: referred_cfg.properties[backref_name] = rel map_config.properties[ |