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POEntity Framework: Duplicate Records in Many-to-Many relationship
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  1. POEntity Framework: Duplicate Records in Many-to-Many relationship
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    copied!<p>I have following entity framework code first code. The tables are created and data is inserted. However there are duplicate records in Club table.</p> <p>My operations are:-</p> <ol> <li><p>Create clubs using club creation app</p></li> <li><p>Create persons using person app</p></li> </ol> <p>How to avoid the duplicate entry?</p> <p><img src="https://i.stack.imgur.com/hoMZC.png" alt="enter image description here"></p> <pre><code> static void Main(string[] args) { Database.SetInitializer&lt;NerdDinners&gt;(new MyInitializer()); CreateClubs(); InsertPersons(); } public static void CreateClubs() { string connectionstring = "Data Source=.;Initial Catalog=NerdDinners;Integrated Security=True;Connect Timeout=30"; using (var db = new NerdDinners(connectionstring)) { Club club1 = new Club(); club1.ClubName = "club1"; Club club2 = new Club(); club2.ClubName = "club2"; Club club3 = new Club(); club3.ClubName = "club3"; db.Clubs.Add(club1); db.Clubs.Add(club2); db.Clubs.Add(club3); int recordsAffected = db.SaveChanges(); } } public static Club GetClubs(string clubName) { string connectionstring = "Data Source=.;Initial Catalog=NerdDinners;Integrated Security=True;Connect Timeout=30"; using (var db = new NerdDinners(connectionstring)) { //var query = db.Clubs.Where(p =&gt; p.ClubName == clubName); var query = db.Clubs.SingleOrDefault(p =&gt; p.ClubName == clubName); return query; } } public static void InsertPersons() { string connectionstring = "Data Source=.;Initial Catalog=NerdDinners;Integrated Security=True;Connect Timeout=30"; using (var db = new NerdDinners(connectionstring)) { Club club1 = GetClubs("club1"); Club club2 = GetClubs("club2"); Club club3 = GetClubs("club3"); Person p1 = new Person(); p1.PersonName = "Person1"; Person p2 = new Person(); p2.PersonName = "Person2"; List&lt;Club&gt; clubsForPerson1 = new List&lt;Club&gt;(); clubsForPerson1.Add(club1); clubsForPerson1.Add(club3); List&lt;Club&gt; clubsForPerson2 = new List&lt;Club&gt;(); clubsForPerson2.Add(club2); clubsForPerson2.Add(club3); p1.Clubs = clubsForPerson1; p2.Clubs = clubsForPerson2; db.Persons.Add(p1); db.Persons.Add(p2); int recordsAffected = db.SaveChanges(); } } </code></pre> <p>Domain</p> <pre><code>public class Person { public int PersonId { get; set; } public string PersonName { get; set; } public virtual ICollection&lt;Club&gt; Clubs { get; set; } } public class Club { public int ClubId { get; set; } public string ClubName { get; set; } public virtual ICollection&lt;Person&gt; Members { get; set; } } //System.Data.Entity.DbContext is from EntityFramework.dll public class NerdDinners : System.Data.Entity.DbContext { public NerdDinners(string connString): base(connString) { } protected override void OnModelCreating(DbModelBuilder modelbuilder) { //Fluent API - Plural Removal modelbuilder.Conventions.Remove&lt;PluralizingTableNameConvention&gt;(); } public DbSet&lt;Person&gt; Persons { get; set; } public DbSet&lt;Club&gt; Clubs { get; set; } } </code></pre>
 

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