Here’s what you’d include in your components table. CREATE TABLE `components` ( `id` int(10) unsigned NOT NULL auto_increment, `typeId` int(10) unsigned NOT NULL, `moreInfo` VARCHAR(32), — etc PRIMARY KEY (`id`), KEY `type` (`typeId`) CONSTRAINT `myForeignKey` FOREIGN KEY (`typeId`) REFERENCES `types` (`id`) ON DELETE CASCADE ON UPDATE CASCADE ) Just remember that you need to use … Read more
Here is how I do it: from django.contrib.contenttypes.models import ContentType from django.contrib.contenttypes import fields class Photo(models.Model): picture = models.ImageField(null=True, upload_to=’./images/’) caption = models.CharField(_(“Optional caption”),max_length=100,null=True, blank=True) content_type = models.ForeignKey(ContentType) object_id = models.PositiveIntegerField() content_object = fields.GenericForeignKey(‘content_type’, ‘object_id’) class Article(models.Model): …. images = fields.GenericRelation(Photo) You would add something like content_type = models.ForeignKey(ContentType) object_id = models.PositiveIntegerField() content_object = fields.GenericForeignKey(‘content_type’, … Read more
Sure – you can… ModelAdmin specific ordering via formfield_for_foreignkey Set default global ordering via a Manager Set default ordering via model meta class Form specific ordering then passed to your ModelAdmin ModelAdmin specific method: (the other methods are in my answer in the post linked to above) class MyModelAdmin(admin.ModelAdmin): def formfield_for_foreignkey(self, db_field, request, **kwargs): if … Read more
There is a conflict between your foreign key property in class Dettaglio… public virtual int IDTEST { get; set; } …which has a non-nullable type (int) and therefore cannot be optional and your mapping… this.HasOptional(t => t.TEST_TABLE) //… …where you want the relationship to be optional. If you indeed want an optional relationship use a … Read more
No. That is, you cannot create a foreign key constraint this way. You can however, use a foreign key without a foreign key constraint. All a foreign key is, is the value of another table’s (or another record in the same table) primary key, which can be used in joins. In fact, you could reference … Read more
The following will return the name of the foreign keys in the current database that are disabled i.e. WITH NOCHECK For SQL Server 2005/2008: select * from sys.foreign_keys where is_disabled=1 There was some discussion in the answer about the difference between disabled & not trusted. What’s below explains the differnce Here’s some code to clarify … Read more
This problem happens because you are referencing the same object more than once. This is not a limitation of EF, but rather a safety feature to ensure you are not inserting the same object with two different IDs. So to achieve what you are trying to do, is simply create a new object and add … Read more
You don’t need to pass the department id, the instance itself is enough. The following should work just fine: new_team = Team( nickname = team_name, employee_id = employee_id, department_id = Department.objects.get(password = password, department_name = department_name)) Just a note: don’t ever name your foreign fields something_id. That something is enough. Django is meant to make … Read more
For recent versions (SQLAlchemy ~0.7) the SQLAlchemy homepage says: PoolListener is deprecated. Please refer to PoolEvents. Then the example by CarlS becomes: engine = create_engine(database_url) def _fk_pragma_on_connect(dbapi_con, con_record): dbapi_con.execute(‘pragma foreign_keys=ON’) from sqlalchemy import event event.listen(engine, ‘connect’, _fk_pragma_on_connect)
[NEW ANSWER] Thanks to @NeverEndingQueue for bringing this up. It seems MySQL has finally fixed this issue. I’m not sure which version this problem was first fixed in, but right now I tested with the following version and the problem is not there anymore: mysql> SHOW VARIABLES LIKE “%version%”; +————————-+——————————+ | Variable_name | Value | … Read more