Inverse Property in EF Core

Question

How to apply Inverse Property in Ef Core I gone through so many examples but didnt helps me. So

my models like this
public class Customer
{

    public string Name { get; set; }
    public int AddedByID { get; set; }
    public int EditedByID { get; set; }
    public int DeletedByID { get; set; }
    [InverseProperty("Customers")]
    [ForeignKey("AddedByID")]
    public virtual UserLogin AddedBy { get; set; }
    [ForeignKey("EditedByID")]
    public virtual UserLogin EditedBy { get; set; }
    [ForeignKey("DeletedByID")]
    public virtual UserLogin DeletedBy { get; set; }

}
public class Vendor
{

    public string Name { get; set; }
    public int AddedByID { get; set; }
    public int EditedByID { get; set; }
    public int DeletedByID { get; set; }
    [InverseProperty("Vendors")]
    [ForeignKey("AddedByID")]
    public virtual UserLogin AddedBy { get; set; }
    [ForeignKey("EditedByID")]
    public virtual UserLogin EditedBy { get; set; }
    [ForeignKey("DeletedByID")]
    public virtual UserLogin DeletedBy { get; set; }

}
public class UserLogin
{
public UserLogin()
{
Customers = new HashSet<Customer>();
Vendors = new HashSet<Vendor>();

    }

public virtual ICollection<Customer> Customers { get; set; }
public virtual ICollection<Vendor> Vendors { get; set; }
}

this only works if I use only model (Customer) if Add this same properties into vendor then it throw error - Unable to determine the relationship represented by navigation 'Custom.Edited By' of type 'UserLogin'. Either manually configure the relationship, or ignore this property using the '[NotMapped]' attribute or by using 'EntityTypeBuilder.Ignore' in 'OnModelCreating'.'

this error is not show if I dont use vendor model

so How do I apply inverse property here

Answer 1

Hi @Prathamesh Shende ,

You can set the foreign key to nullable and use InverseProperty as below:

public class Customer  
{  
    [Key]  
    public int ID { get; set; }  
    public string Name { get; set; }  
    [ForeignKey("AddedBy")]  
    public int? AddedByID { get; set; }  
    [ForeignKey("EditedBy")]  
    public int? EditedByID { get; set; }  
    [ForeignKey("DeletedBy")]  
    public int? DeletedByID { get; set; }   
    public UserLogin AddedBy { get; set; }   
    public UserLogin EditedBy { get; set; }   
    public UserLogin DeletedBy { get; set; }  
}  
public class Vendor  
{  
    [Key]  
    public int ID { get; set; }  
    public string Name { get; set; }  
    [ForeignKey("AddedBy")]  
    public int? AddedByID { get; set; }  
    [ForeignKey("EditedBy")]  
    public int? EditedByID { get; set; }  
    [ForeignKey("DeletedBy")]  
    public int? DeletedByID { get; set; }   
    public UserLogin AddedBy { get; set; }  
    public UserLogin EditedBy { get; set; }  
    public UserLogin DeletedBy { get; set; }  
}  
public class UserLogin  
{   
    public UserLogin()  
    {  
        CustomersAdded = new List<Customer>();  
        VendorsAdded = new List<Vendor>();  
    }  

    [Key]  
    public int Id { get; set; }  
    public string Name { get; set; }  

    [InverseProperty("AddedBy")]  
    public List<Customer> CustomersAdded { get; set; }  
    [InverseProperty("EditedBy")]  
    public List<Customer> CustomersEdited { get; set; }  
    [InverseProperty("DeletedBy")]  
    public List<Customer> CustomersDeleted { get; set; }  
    [InverseProperty("AddedBy")]  
    public List<Vendor> VendorsAdded { get; set; }  
    [InverseProperty("EditedBy")]  
    public List<Vendor> VendorsEdited { get; set; }  
    [InverseProperty("DeletedBy")]  
    public List<Vendor> VendorsDeleted { get; set; }  
}  

And configure the cascading delete as NoAction:

public class ApplicationDbContext : IdentityDbContext  
{  
    public ApplicationDbContext(DbContextOptions<ApplicationDbContext> options)  
        : base(options)  
    {  
    }    

    public DbSet<UserLogin> UserLogin { get; set; }  
    public DbSet<Customer> Customers { get; set; }  
    public DbSet<Vendor> Vendors { get; set; }  

    protected override void OnModelCreating(ModelBuilder modelBuilder)  
    {  
        base.OnModelCreating(modelBuilder);  
        modelBuilder.Entity<Customer>()  
            .HasOne(c => c.AddedBy)  
            .WithMany(c=>c.CustomersAdded)  
            .OnDelete(DeleteBehavior.NoAction);  
        modelBuilder.Entity<Customer>()  
            .HasOne(c => c.EditedBy)  
           .WithMany(c => c.CustomersEdited)  
            .OnDelete(DeleteBehavior.NoAction);  
        modelBuilder.Entity<Customer>()  
            .HasOne(c => c.DeletedBy)  
           .WithMany(c => c.CustomersDeleted)  
            .OnDelete(DeleteBehavior.NoAction);  
        modelBuilder.Entity<Vendor>()  
            .HasOne(c => c.AddedBy)  
           .WithMany(c => c.VendorsAdded)  
            .OnDelete(DeleteBehavior.NoAction);  
        modelBuilder.Entity<Vendor>()  
            .HasOne(c => c.EditedBy)  
            .WithMany(c=>c.VendorsEdited)  
            .OnDelete(DeleteBehavior.NoAction);  
        modelBuilder.Entity<Vendor>()  
            .HasOne(c => c.DeletedBy)  
            .WithMany(c=>c.VendorsDeleted)  
            .OnDelete(DeleteBehavior.NoAction);   
    }  
}  

The generated table as below:

Then, you can add/remove the entity via the ApplicationDbContext, like this:

        _context.UserLogin.Add(new UserLogin()  
        {  
           Name="AA",  
           CustomersAdded= new List<Customer>()  
           {  
               new Customer(){ Name="Tom"}  
           },  
            CustomersEdited = new List<Customer>()  
           {  
               new Customer(){ Name="John"}  
           },  
            VendorsAdded = new List<Vendor>()  
            {  
                new Vendor(){ Name="Jack"}  
            }  
        });  
        _context.SaveChanges();  

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Best regards,
Dillion