title: Code First Foreign Key - Multiplicity is not valid in Role
body: <p><strong>My Model as below:</strong></p>
  
  <pre><code>public class Form1
  {
      [Key]
      public long Id { get; set; }
  
      [Required]
      [Display(Name = "Name")]
      public string Name { get; set; }
  
      [Required]
      [Display(Name = "Email")]
      public string Email { get; set; }
  
      [Display(Name = "Department", Prompt = "Please enter your department")]
      public string Department { get; set; }
  
  
      public  Form1 Form1{ get; set; }
      public  Form2 Form2 { get; set; }
  }
  </code></pre>
  
  <p>Second Class (Need one to one relationship) so setting Foreign key</p>
  
  <pre><code>public class Form2
  {
      [Key]
      public long Form2_ID { get; set; }
  
      [ForeignKey("Form1")]
      public long Id { get; set; }
  
  
      //Mobile Home Page
      public string Location1 { get; set; }
      [DataType(DataType.MultilineText)] 
  
      //[ForeignKey("Id")]  //Even this is not working
      public  Form1 Form1 { get; set; }
  
  }
  </code></pre>
  
  <p>Third class here. Same as above and needed One to One relationship Foreign Key.</p>
  
  <pre><code>public class Form3
  {
      [Key]
      public long Form3_ID { get; set; }
  
      [ForeignKey("Form1")]
      public long Id { get; set; }
  
      [Display(Name = "Rhombus")]
      public bool Rhombus { get; set; }
  
  
      public  Form1 Form1 { get; set; }
  }
  </code></pre>
  
  <p>I am getting following error.</p>
  
  <p><em>One or more validation errors were detected during model generation:
  \tSystem.Data.Entity.Edm.EdmAssociationEnd: : Multiplicity is not valid in Role 'Form2_Form1_Source' in relationship 'Form2_Form1'. Because the Dependent Role properties are not the key properties, the upper bound of the multiplicity of the Dependent Role must be '</em>'.*</p>
  
  <p>What wrong I am doing here?</p>
  
  <p>Looks like I am struck up in this.!! Maybe Database first approach is better.</p>