many-to-many
How to organise a many to many relationship in MongoDB
What I’ve seen done, and what I currently use are embedded arrays with node id’s in each document. So document user1 has property groups: [id1,id2] And document group1 has property users: [user1]. Document group2 also has property users: [user1]. This way you get a Group object and easily select all related users, and the same … Read more
Django removing object from ManyToMany relationship
my_mood.interests.remove(my_interest) Django’s Relations Docs Note: you might have to get an instance of my_mood and my_interest using Django’s QuerySet API before you can execute this code.
how to have relations many to many in redis
With Redis, relationships are typically represented by sets. A set can be used to represent a one-way relationship, so you need one set per object to represent a many-to-many relationship. It is pretty useless to try to compare a relational database model to Redis data structures. With Redis, everything is stored in a denormalized way. … Read more
Entity Framework 4.1+ many-to-many relationships change tracking
Here is how to find all the changed many-to-many relationships. I’ve implemented the code as extension methods: public static class IaExtensions { public static IEnumerable<Tuple<object, object>> GetAddedRelationships( this DbContext context) { return GetRelationships(context, EntityState.Added, (e, i) => e.CurrentValues[i]); } public static IEnumerable<Tuple<object, object>> GetDeletedRelationships( this DbContext context) { return GetRelationships(context, EntityState.Deleted, (e, i) => e.OriginalValues[i]); … Read more
getting the value of an extra pivot table column laravel
When using Many to Many relationships with Eloquent, the resulting model automatically gets a pivot attribute assigned. Through that attribute you’re able to access pivot table columns. Although by default there are only the keys in the pivot object. To get your columns in there too, you need to specify them when defining the relationship: … Read more
Self-referencing many-to-many recursive relationship code first Entity Framework
By convention, Code First will take uni-directional associations as one to many. Therefore you need to use fluent API to let Code First know that you want to have a many to many self referencing association: protected override void OnModelCreating(ModelBuilder modelBuilder) { modelBuilder.Entity<Member>().HasMany(m => m.Friends).WithMany().Map(m => { m.MapLeftKey(“MemberId”); m.MapRightKey(“FriendId”); m.ToTable(“MembersFriends”); } ); }
NHibernate – Many to Many Query using Junction/Joiner Table
One way how to achieve this, could be to create as many subqueries joined by AND, as many attributes must be found/related to searched files I searching for name / value The first solution works with the name/value pairs, from upper layer. I.e user selected mode to be read-only… (the second will be a bit … Read more
Django Many-to-Many (m2m) Relation to same model
Technically, I’m pretty sure “MyUser” or “self” will work, as long as it’s a string in either case. You just can’t pass MyUser, the actual class. However, the docs always use “self”. Using “self” is not only more explicit about what’s actually happening, but it’s impervious to class name changes. For example, if you later … Read more
Django – Cascade deletion in ManyToManyRelation
I think you are misunderstanding the nature of a ManyToMany relationship. You talk about “the corresponding BlogEntry” being deleted. But the whole point of a ManyToMany is that each BlogEntryRevision has multiple BlogEntries related to it. (And, of course, each BlogEntry has multiple BlogEntryRevisions, but you know that already.) From the names you have used, … Read more