[Key, Column(Order = 0)] public string ProgrammerId { get; set; } [Key, Column(Order = 1)] public int SkillId { get; set; } public virtual ProgrammerProfile Programmer { get; set; } public virtual Skill Skill { get; set; } public int KnowledgeLevel { get; set; }
  • And how did you try and what did not work out? - Andrey NOP

1 answer 1

Suppose you have such an entity:

 public class EntityProg { [Key, Column(Order = 0)] public string ProgrammerId { get; set; } [Key, Column(Order = 1)] public int SkillId { get; set; } public int KnowledgeLevel { get; set; } public virtual ProgrammerProfile Programmer { get; set; } public virtual Skill Skill { get; set; } }

Suppose you have a DbSet such entities in the context:

 public virtual DbSet<EntityProg> EntityProgs { get; set; }

Suppose you want to delete one such entity by the two keys programmerId and skillId :

 // попытаемся найти сущность по двум ключам var record = context.EntityProgs .SingleOrDefault(_ => _.ProgrammerId == programmerId && _.SkillId == skillId); // если такая сущность найдена, удалим if (record != null) { context.EntityProgs.Remove(record); context.SaveChanges(); }

Also, there is a method of removing the collection RemoveRange , with which you can delete several entities at once. It's simple, you first need to find the entity in the context, pull it out and put it into a variable, and then transfer it to the desired DbSet method ( Remove or RemoveRange - depending on whether you need to delete one entity or several).

Alternatively, you can go another way (using the Attach method to not select and send a SELECT before deleting):

 var entityProg = new EntityProg { ProgrammerId = programmerId, SkillId = skillId }; context.EntityProgs.Attach(entityProg); context.EntityProgs.Remove(entityProg); context.SaveChanges();

But that's not all, you can go ahead and mark the entity as remote through its state, for example:

 var entityProg = new EntityProg { ProgrammerId = programmerId, SkillId = skillId }; context.EntityProgs.Attach(entityProg); context.Entry(entityProg).State = EntityState.Deleted; context.SaveChanges();

Source link: Delete a single record from Entity Framework?

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    Well, the standard recommendation is to use Attach, so as not to send select before deleting (besides, we have a primary key and the object certainly exists in one copy) - Andrey NOP