在实体框架中使用关联属性

Question

I am just to set up a model in which you have news articles and topics they belong to. This is a simple association but now it get's a bit "extended". One of those topic association can be marked as the "mainTopic".

I've set up 3 tables:

• avsn_content , containing the newsArticles identified by id

• avsn_content_topics , containing the assoc, having assocId , id , topicId and a column indicating the mainTopic

• avsn_topics , containing the topic, identified by topicId

Furthermore, I have models for these three tables. My association model is designed as follows:

[Table("avsn_content_topcis")]
public class TopicNewsModel
{
    [Key]
    [Column("assocId")]
    public int Id { get; set; }

    public NewsArticleModel NewsArticle { get; set; }

    public TopicModel Topic { get; set; }

    [Column("mainTopic")]
    public bool IsMainTopic { get; set; }
}

My relationship setup looks like this:

modelBuilder.Entity<NewsArticleModel>()
                    .HasMany(x => x.Topics)                        
                    .WithMany()
                    .Map(m => m.MapLeftKey("id")
                               .MapRightKey("topicId")
                               .ToTable("avsn_content_topics"));

I am getting this error:

One or more validation errors were detected during model generation:

NewsArticleModelTopicNewsModel: Name: The EntitySet 'NewsArticleModelTopicNewsModel' with schema 'dbo' and table 'avsn_content_topics' was already defined. Each EntitySet must refer to a unique schema and table.

Removing the ToTable option does not help it, so what am I doing wrong here?

Answer 1

Well, found the answer right after posting this. Trying to pick the problem from the other end of the rope showed that I had to start off from the TopicNewsModel instead from the NewsModel.

  modelBuilder.Entity<TopicNewsModel>()
                    .HasRequired(topicNews => topicNews.NewsArticle)
                    .WithMany(news => news.Topics)
                    .Map(m => m.MapKey("id"));

        modelBuilder.Entity<TopicNewsModel>()
                    .HasRequired(topicNews => topicNews.Topic)
                    .WithMany()
                    .Map(m => m.MapKey("topicId"));