How to Implement a Many-to-Many Relationship with Additional Properties in EF Core?

Use the associated table in EF Core to create a multi -to -many relationship

Scene

Suppose we have the following data model:

Configure associated with Fluent API

<code class="language-csharp">public class Member
{
    public int MemberID { get; set; }
    public string FirstName { get; set; }
    public string LastName { get; set; }
    public virtual ICollection<MemberComment> MemberComments { get; set; }
}

public class Comment
{
    public int CommentID { get; set; }
    public string Message { get; set; }
    public virtual ICollection<MemberComment> MemberComments { get; set; }
}

public class MemberComment
{
    [Key, Column(Order = 0)]
    public int MemberID { get; set; }
    [Key, Column(Order = 1)]
    public int CommentID { get; set; }
    public virtual Member Member { get; set; }
    public virtual Comment Comment { get; set; }
    public int Something { get; set; }
    public string SomethingElse { get; set; }
}</code>

Unfortunately, the Entity Framework Core (EF Core) does not support the use of a custom connection table to create a multi -to -multiple relationship. EF Core automatically creates and manages the internal connection table to make it unable to access.

Alternative: Create two pairs of multi -relationships

To use a connection table with additional attributes (such as

), we need to establish two one -to -multi -relationship:

MemberComment (The code segment is the same as input, the duplicate here is omitted)

Use association

Now, we can perform various operations on these entities:

Get the member's comment

Get the members with comments
Filter the attribute in the connection table
Create and manage the relationship between entities
Delete relationship and entity
• Query

Relations management

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