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POEntity framework 4 many-to-many insertion?
 

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  1. POEntity framework 4 many-to-many insertion?
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    <p>I'm not very familiar with the many-to-many insertion process using Entity Framework 4, POCO. I have a blog with 3 tables: Post, Comment, and Tag. A <strong>Post</strong> can have many <strong>Tags</strong> and a <strong>Tag</strong> can be in many <strong>Posts</strong>. Here are the <strong>Post</strong> and <strong>Tag</strong> models:</p> <pre><code>public class Tag { public int Id { get; set; } [Required] [StringLength(25, ErrorMessage = "Tag name can't exceed 25 characters.")] public string Name { get; set; } public virtual ICollection&lt;Post&gt; Posts { get; set; } } public class Post { public int Id { get; set; } [Required] [StringLength(512, ErrorMessage = "Title can't exceed 512 characters")] public string Title { get; set; } [Required] [AllowHtml] public string Content { get; set; } public string FriendlyUrl { get; set; } public DateTime PostedDate { get; set; } public bool IsActive { get; set; } public virtual ICollection&lt;Comment&gt; Comments { get; set; } public virtual ICollection&lt;Tag&gt; Tags { get; set; } } </code></pre> <p>Now when I'm adding a new post, I'm not sure what would be the right way to do. I'm thinking that I'll have a textbox where I can select multiple tags for that post (this part is already done), in my controller, I will check to see if the tag is already exists or not, if not, then I will insert the new tag. But I'm not even sure based on the models that I've created for EF, will they create a PostsTags table, or they are creating just a Tags and a Posts table and links between the two?</p> <p>How would I insert the new <strong>Post</strong> and set the tags to that post? Is it just <code>newPost.Tags = Tags</code> (where Tags are the one that got selected, do I even need to check to see if they already exists?), and then something like <code>_post.Add(newPost);</code>?</p> <p>Thanks.</p>
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    1. USSaxman
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    1. COHey Saxman, are you setting a custom Initializer? (DbDatabase.SetInitializer) If you are changing your model, you should let EF also build your database so you model matches the database. This may be the reason why your Many-to-Many did not work like it should have. If you need to know how to do this let me know! IMHO, you REALLY should not be defining a lookup entity in your domain model. EF will do this work for you and make it transparent.
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    2. COHi Paul, I do have EF set to `DropCreateDatabaseIfModelChanges`, I will try the approach that you have on the other post again to see if many-to-many relationship work. Thanks.
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Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

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