related.py 文件源码

def create_many_to_many_intermediary_model(field, klass):
    from django.db import models

    def set_managed(model, related, through):
        through._meta.managed = model._meta.managed or related._meta.managed

    to_model = resolve_relation(klass, field.remote_field.model)
    name = '%s_%s' % (klass._meta.object_name, field.name)
    lazy_related_operation(set_managed, klass, to_model, name)

    to = make_model_tuple(to_model)[1]
    from_ = klass._meta.model_name
    if to == from_:
        to = 'to_%s' % to
        from_ = 'from_%s' % from_

    meta = type(str('Meta'), (object,), {
        'db_table': field._get_m2m_db_table(klass._meta),
        'auto_created': klass,
        'app_label': klass._meta.app_label,
        'db_tablespace': klass._meta.db_tablespace,
        'unique_together': (from_, to),
        'verbose_name': _('%(from)s-%(to)s relationship') % {'from': from_, 'to': to},
        'verbose_name_plural': _('%(from)s-%(to)s relationships') % {'from': from_, 'to': to},
        'apps': field.model._meta.apps,
    })
    # Construct and return the new class.
    return type(str(name), (models.Model,), {
        'Meta': meta,
        '__module__': klass.__module__,
        from_: models.ForeignKey(
            klass,
            related_name='%s+' % name,
            db_tablespace=field.db_tablespace,
            db_constraint=field.remote_field.db_constraint,
            on_delete=CASCADE,
        ),
        to: models.ForeignKey(
            to_model,
            related_name='%s+' % name,
            db_tablespace=field.db_tablespace,
            db_constraint=field.remote_field.db_constraint,
            on_delete=CASCADE,
        )
    })