我们从Python开源项目中，提取了以下18个代码示例，用于说明如何使用django.db.models.SET_NULL。
def __new__(cls, name, bases, namespace): panels = namespace['panels'] blueprint_names = namespace['blueprint_names'] for member in blueprint_names: namespace[member.name] = models.ForeignKey( 'a4projects.Project', on_delete=models.SET_NULL, null=True, blank=True, related_name='example_project_{}'.format(member.name), help_text='Please select an exemplary {} project.'.format( member.value ), ) panels += [edit_handlers.FieldPanel(member.name)] return super().__new__(cls, name, bases, namespace)
def forwards(self, orm): # Changing field 'File.owner' db.alter_column(u'filer_file', 'owner_id', self.gf('django.db.models.fields.related.ForeignKey')(null=True, on_delete=models.SET_NULL, to=orm['auth.User'])) # Changing field 'Folder.owner' db.alter_column(u'filer_folder', 'owner_id', self.gf('django.db.models.fields.related.ForeignKey')(null=True, on_delete=models.SET_NULL, to=orm['auth.User'])) # Changing field 'FolderPermission.user' db.alter_column(u'filer_folderpermission', 'user_id', self.gf('django.db.models.fields.related.ForeignKey')(null=True, on_delete=models.SET_NULL, to=orm['auth.User']))
def http_skill_preview_url(self): return get_http_image_url_from_path(self.skill_preview) # action_skill = models.OneToOne('ActionSkill', verbose_name=_('Action Skill'), related_name='skill', null=True, # on_delete=models.SET_NULL) # evolved_action_skill = models.OneToOne('ActionSkill', verbose_name=_('Evolved Action Skill'), # related_name='evolved skill', null=True, on_delete=models.SET_NULL)
def __init__(self, *args, **kwargs): kwargs.setdefault('on_delete', models.SET_NULL) super().__init__(*args, **kwargs)
def test_user(self): field = ServeLog._meta.get_field('user') self.assertModelPKField(field, User, models.SET_NULL, True, False)
def test_image(self): field = AbstractCard._meta.get_field('image') self.assertModelPKField(field, 'wagtailimages.Image', models.SET_NULL, True, True)
def test_feed_image(self): field = BasicPage._meta.get_field('feed_image') self.assertModelPKField(field, Image, models.SET_NULL, True, True) # properties
def test_link_page(self): field = AbstractLinkFields._meta.get_field('link_page') self.assertModelPKField(field, 'wagtailcore.Page', models.SET_NULL, True, True)
def test_link_document(self): field = AbstractLinkFields._meta.get_field('link_document') self.assertModelPKField(field, 'wagtaildocs.Document', models.SET_NULL, True, True)
def user_pre_delete(instance, **kwargs): # ??? ForeignKey(on_delete=models.SET_NULL) ???? Log.user ???? Log.objects.filter(user=instance).update(user=None)
def __init__(self, *args, **kwargs): defaults = { 'verbose_name': _('Category'), 'to': Category, 'on_delete': models.SET_NULL, 'null': True, 'blank': True, 'related_name': '+', } defaults.update(kwargs) super().__init__(**defaults)
def forwards(self, orm): # Adding model 'Network' db.create_table('firmcreator_network', ( ('id', self.gf('django.db.models.fields.AutoField')(primary_key=True)), ('user', self.gf('django.db.models.fields.related.ForeignKey')(to=orm['auth.User'])), ('name', self.gf('django.db.models.fields.CharField')(unique=True, max_length=100)), ('slug', self.gf('autoslug.fields.AutoSlugField')(unique_with=(), max_length=50, populate_from='name', blank=True)), ('description', self.gf('django.db.models.fields.TextField')()), )) db.send_create_signal('firmcreator', ['Network']) # Adding model 'FwProfile' db.create_table('firmcreator_fwprofile', ( ('id', self.gf('django.db.models.fields.AutoField')(primary_key=True)), ('network', self.gf('django.db.models.fields.related.ForeignKey')(to=orm['firmcreator.Network'])), ('name', self.gf('django.db.models.fields.SlugField')(default='default', max_length=15)), ('slug', self.gf('autoslug.fields.AutoSlugField')(unique_with=(), max_length=50, populate_from=None)), ('description', self.gf('django.db.models.fields.TextField')()), ('creation_date', self.gf('django.db.models.fields.DateTimeField')(default=datetime.datetime.now)), ('path', self.gf('django.db.models.fields.CharField')(max_length=255)), ('based_on', self.gf('django.db.models.fields.related.ForeignKey')(to=orm['firmcreator.FwProfile'], null=True, on_delete=models.SET_NULL, blank=True)), ('include_packages', self.gf('django.db.models.fields.TextField')(blank=True)), ('include_files', self.gf('altermeshfc.firmcreator.fields.JSONField')(default='{}')), )) db.send_create_signal('firmcreator', ['FwProfile']) # Adding unique constraint on 'FwProfile', fields ['network', 'name'] db.create_unique('firmcreator_fwprofile', ['network_id', 'name']) # Adding model 'FwJob' db.create_table('firmcreator_fwjob', ( ('id', self.gf('django.db.models.fields.AutoField')(primary_key=True)), ('status', self.gf('django.db.models.fields.CharField')(default='WAITING', max_length=10)), ('profile', self.gf('django.db.models.fields.related.ForeignKey')(to=orm['firmcreator.FwProfile'])), ('user', self.gf('django.db.models.fields.related.ForeignKey')(to=orm['auth.User'])), ('job_data', self.gf('altermeshfc.firmcreator.fields.JSONField')(default='{}')), )) db.send_create_signal('firmcreator', ['FwJob'])
def forwards(self, orm): # Adding field 'Node.boot_interface' db.add_column('maasserver_node', 'boot_interface', self.gf('django.db.models.fields.related.ForeignKey')(related_name='+', on_delete=models.SET_NULL, default=None, to=orm['maasserver.Interface'], blank=True, null=True), keep_default=False) # Adding field 'Interface.node' db.add_column('maasserver_interface', 'node', self.gf('django.db.models.fields.related.ForeignKey')(to=orm['maasserver.Node'], null=True, blank=True), keep_default=False) # Adding field 'Interface.mac_address' db.add_column('maasserver_interface', 'mac_address', self.gf('maasserver.fields.MACAddressField')(null=True, blank=True), keep_default=False)
def backwards(self, orm): # Adding field 'Node.pxe_mac' db.add_column('maasserver_node', 'pxe_mac', self.gf('django.db.models.fields.related.ForeignKey')(related_name='+', on_delete=models.SET_NULL, default=None, to=orm['maasserver.MACAddress'], blank=True, null=True), keep_default=False) # Adding field 'Interface.mac' db.add_column('maasserver_interface', 'mac', self.gf('django.db.models.fields.related.ForeignKey')(to=orm['maasserver.MACAddress'], null=True, blank=True), keep_default=False) # Add the unique constraint for mac_id. db.execute( "CREATE UNIQUE INDEX maasserver_interface_mac_id_name_idx ON " "maasserver_interface (mac_id, name) WHERE mac_id IS NOT NULL")
def forwards(self, orm): # Adding field 'Node.gateway_link_ipv4' db.add_column('maasserver_node', 'gateway_link_ipv4', self.gf('django.db.models.fields.related.ForeignKey')(related_name='+', on_delete=models.SET_NULL, default=None, to=orm['maasserver.StaticIPAddress'], blank=True, null=True), keep_default=False) # Adding field 'Node.gateway_link_ipv6' db.add_column('maasserver_node', 'gateway_link_ipv6', self.gf('django.db.models.fields.related.ForeignKey')(related_name='+', on_delete=models.SET_NULL, default=None, to=orm['maasserver.StaticIPAddress'], blank=True, null=True), keep_default=False)
def backwards(self, orm): # Adding model 'Network' db.create_table('maasserver_network', ( ('dns_servers', self.gf('django.db.models.fields.CharField')(max_length=255, null=True, blank=True)), ('netmask', self.gf('maasserver.fields.MAASIPAddressField')(max_length=39)), ('description', self.gf('django.db.models.fields.TextField')(blank=True)), ('default_gateway', self.gf('maasserver.fields.MAASIPAddressField')(max_length=39, null=True, blank=True)), ('ip', self.gf('maasserver.fields.MAASIPAddressField')(max_length=39, unique=True)), ('vlan_tag', self.gf('django.db.models.fields.PositiveSmallIntegerField')(unique=True, null=True, blank=True)), ('id', self.gf('django.db.models.fields.AutoField')(primary_key=True)), ('name', self.gf('django.db.models.fields.CharField')(max_length=255, unique=True)), )) db.send_create_signal('maasserver', ['Network']) # Adding model 'DHCPLease' db.create_table('maasserver_dhcplease', ( ('ip', self.gf('maasserver.fields.MAASIPAddressField')(max_length=39, unique=True)), ('mac', self.gf('maasserver.fields.MACAddressField')()), ('nodegroup', self.gf('django.db.models.fields.related.ForeignKey')(to=orm['maasserver.NodeGroup'])), ('id', self.gf('django.db.models.fields.AutoField')(primary_key=True)), )) db.send_create_signal('maasserver', ['DHCPLease']) # Adding model 'MACAddress' db.create_table('maasserver_macaddress', ( ('node', self.gf('django.db.models.fields.related.ForeignKey')(to=orm['maasserver.Node'], null=True, blank=True)), ('updated', self.gf('django.db.models.fields.DateTimeField')()), ('created', self.gf('django.db.models.fields.DateTimeField')()), ('mac_address', self.gf('maasserver.fields.MACAddressField')(unique=True)), ('id', self.gf('django.db.models.fields.AutoField')(primary_key=True)), ('cluster_interface', self.gf('django.db.models.fields.related.ForeignKey')(default=None, to=orm['maasserver.NodeGroupInterface'], null=True, on_delete=models.SET_NULL, blank=True)), )) db.send_create_signal('maasserver', ['MACAddress']) # Adding M2M table for field networks on 'MACAddress' db.create_table('maasserver_macaddress_networks', ( ('id', models.AutoField(verbose_name='ID', primary_key=True, auto_created=True)), ('macaddress', models.ForeignKey(orm['maasserver.macaddress'], null=False)), ('network', models.ForeignKey(orm['maasserver.network'], null=False)) )) db.create_unique('maasserver_macaddress_networks', ['macaddress_id', 'network_id'])
def forwards(self, orm): # Adding field 'Node.boot_disk' db.add_column('maasserver_node', 'boot_disk', self.gf('django.db.models.fields.related.ForeignKey')(related_name='+', on_delete=models.SET_NULL, default=None, to=orm['maasserver.PhysicalBlockDevice'], blank=True, null=True), keep_default=False)
