how to create one to one relationship in entity .net framework?

Question

Hi I want create one to one relation ship with entity .net framework in C# windows form. but i get this error:

System.Data.Entity.ModelConfiguration.ModelValidationException: 'One or more validation errors were detected during model generation:

person_pos_Source: : Multiplicity is not valid in Role 'person_pos_Source' in relationship 'person_pos'. Because the Dependent Role properties are not the key properties, the upper bound of the multiplicity of the Dependent Role must be '*'. '

this is my code for person and their position table:

   public class pos
    {
        [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
        [Key]
        public Guid id { get; set; }

        [Required, Column(TypeName = "nvarchar")]
        [MaxLength(50)]
        public string name { get; set; }

        public virtual person person { get; set; }

    }





 public class person
    {
        [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
        [Key]
        public Guid id { get; set; } 
        
         [Required, Column(TypeName = "nvarchar")]
        [MaxLength(50)]
        public string name { get; set; }
        [Required, Column(TypeName = "nvarchar")]
        [MaxLength(50)]
        public string family { get; set; }
        public int? age { get; set; }

        public DateTime Createdata { get; set; }
        
        [ForeignKey("pos")]
        public Guid posId { get; set; }

        public virtual pos pos { get; set; }


    }

how can I fix this?

Answer 1

A few things are fundamentally wrong here.

A 1:1 relationship can be achieved by having the primary of another table as the foreign key and also for the other referred table (non-nullable).

So you should have your relationship like this.

public class Class1
{
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    [Key]
    public int Id {get;set;}
    [Required]
    public virtual Class2 Class2 {get;set;}
}

public class Class2
{
    [Key, ForeignKey("Class1")]
    public int Id {get;set;}
    [Required]
    public virtual Class1 Class1 {get;set;}
}