I just started using Code first approach for creating databases. I have following 3 tables :
public class TagDatabase
{
[Key]
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int TagID { get; set; }
public string TagName { get; set; }
public string Description { get; set; }
public int Count { get; set; }
[ForeignKey("TagTypes")]
public virtual int TagTypeID { get; set; }
public virtual ICollection<TagTypesDb> TagTypes { get; set; }
[ForeignKey("Users")]
public virtual int CreatedBy { get; set; }
public virtual UsersDb Users { get; set; }
}
public class TagTypesDb
{
[Key]
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int TagTypeID { get; set; }
public string TagTypeName { get; set; }
}
public class UsersDb
{
[Key]
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int UserID { get; set; }
public string UserName { get; set; }
}
Here TagDatabse and User and TagType have 1 to 1 replationship. The fluent API code which i used for this is :
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<TagDatabase>()
.HasOptional(a => a.TagTypes)
.WithMany()
.HasForeignKey(u => u.TagTypeID);
modelBuilder.Entity<TagDatabase>()
.HasRequired(a => a.Users)
.WithMany()
.HasForeignKey(u => u.CreatedBy);
}
Now my issue is whenever i am trying to insert data in TagDatabase i got this exception :
TagDatabase_TagTypes: : Multiplicity conflicts with the referential constraint in Role 'TagDatabase_TagTypes_Target' in relationship 'TagDatabase_TagTypes'. Because all of the properties in the Dependent Role are non-nullable, multiplicity of the Principal Role must be '1'.
The TagTypeId property is allowed nulls .so i used HasOptional() in OnModelCreating method.
Cananybody please tell me how to solve this issue and what i am missing here ?
You should make the foreign key property nullable
if the corresponding relationship is optional.
public class TagDatabase
{
//sniff...
[ForeignKey("TagTypes")]
public virtual int? TagTypeID { get; set; } //Since TagTypes is optional, this should be nullable
public virtual ICollection<TagTypesDb> TagTypes { get; set; }
//sniff...
}
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