如何使用Entity Framework 5将PICO类与数据库中的特定表相关联 [英] How do i assosiate my PICO class with a specific table in my database with Entity Framework 5

问题描述

我的数据库中有一个表(多对多表)，两个类A和B都是这样创建的.

I have a table in my db (a many to many table) that two classes A and B have created like this.

    this.HasMany(t => t.TrafficImageQuestions)
       .WithMany(t => t.TrafficImages)
        .Map(m =>
            {
                m.ToTable("TrafficImage_Answers");
                m.MapLeftKey("TrafficImagesGuid");
                m.MapRightKey("TrafficImageQuestionsId");


            });

现在，我想将我的自定义类与同一张表"TrafficImage_Answers"相关联，该类的原因是具有左右键，然后还有一个3. custom属性.

Now i would like to assosiate my custom class to this same table "TrafficImage_Answers", the class offcause have the left and right key and then also a 3. custom property.

(我确实将该列添加到了答案"数据库中)

(i did add the column to the database "Answer")

    public class TrafficImageAnswer
    {
        public System.Guid TrafficImageGuid { get; set; }
        public int TrafficImageQuestionId { get; set; }
        public byte Answer { get; set; }
    }

之所以这样做，是因为我希望实体模型能够跟踪A和B的多对多关系，并且仍然能够查找数据库中的3.属性Answer.

I am doing this as i want entity model to keep track of my many to many relationship of A and B and still be able to look up the 3. property Answer that is in the database.

我尝试过的事情

我尝试执行以下操作:

    this.Property(t => t.TrafficImageQuestionId)
        .HasDatabaseGeneratedOption(DatabaseGeneratedOption.None);
    this.Property(t => t.TrafficImageGuid)
        .HasDatabaseGeneratedOption(DatabaseGeneratedOption.None);

    // Table & Column Mappings
    this.ToTable("TrafficImage_Answers");

但是我知道该表已经存在，逻辑上.我需要告诉它，它仅应使用该表，而不要尝试创建它.(即通过EF 5和程序包管理器中的数据库缓解措施来实现.)

But i get that the table already exists, logic. I need to tell it that it just should use that table and not try to create it. (im doing this with DB mitigrations in EF 5 and Package manager).

推荐答案

不支持.如果要在联结表中具有用于多对多关系的其他字段，则无法再将其映射为多对多关系.每个表只能映射一次，但是同时将表映射到实体和多对多关系会使它映射两次.

That is not supported. If you want to have additional field in the junction table for many-to-many relation you cannot map it as many-to-many any more. Each table can be mapped only once but mapping table to entity and to many-to-many relation in the same time makes it mapped twice.

您必须更改您的 TrafficImageQuestions 和 TrafficImages 以使用与 TrafficImageAnswer 的一对多关系，而不是彼此之间的多对多关系

You must change your TrafficImageQuestions and TrafficImages to use one to many relations with TrafficImageAnswer instead of many-to-many relation with each other.

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