C#•2y ago

✅ Multiple one to many relationships

I've just recently started using ASP.NET and I ran into a bit of a wall Basically:

    public class Reserva
    {
        public int Id { get; set; }

        public string ClienteId { get; set; }
        public ApplicationUser Cliente { get; set; }

        public string FuncionarioId { get; set; }
        public ApplicationUser Funcionario { get; set; }
    }

    public class ApplicationUser : IdentityUser
    {
        public Empresa? Empresa { get; set; }
        public ICollection<Reserva> Reservas { get; set; }
        public ICollection<Reserva> EntregasRecolhas { get; set; }

    }

    public class Reserva
    {
        public int Id { get; set; }

        public string ClienteId { get; set; }
        public ApplicationUser Cliente { get; set; }

        public string FuncionarioId { get; set; }
        public ApplicationUser Funcionario { get; set; }
    }

    public class ApplicationUser : IdentityUser
    {
        public Empresa? Empresa { get; set; }
        public ICollection<Reserva> Reservas { get; set; }
        public ICollection<Reserva> EntregasRecolhas { get; set; }

    }

How do I make a migration of this? I'm getting "Unable to determine the relationship represented by navigation 'ApplicationUser.EntregasRecolhas' of type 'ICollection<Reserva>'. Either manually configure the relationship, or ignore this property using the '[NotMapped]' attribute or by using 'EntityTypeBuilder.Ignore' in 'OnModelCreating'." And I don't know how to proceed without having to manually do it ( which I don't know how to do it either )

5 Replies

Saber•2y ago

because you have 2 different relationships, you need to configure which collection relates to which of those properties. https://learn.microsoft.com/en-us/ef/core/modeling/relationships?tabs=fluent-api%2Cfluent-api-simple-key%2Csimple-key#manual-configuration

Relationships - EF Core

How to configure relationships between entity types when using Entity Framework Core

Marcoelho97OP•2y ago

OH! I had been trying to figure out where to put the manual part but I thought it was in the migrations, which wasn't a solution for me cause my teachers will want to delete them! That makes a lot of sense! Thank you! Another question, though: In the example you showed me:

modelBuilder.Entity<Post>()
            .HasOne(p => p.Blog)
            .WithMany(b => b.Posts);

modelBuilder.Entity<Post>()
            .HasOne(p => p.Blog)
            .WithMany(b => b.Posts);

How does it know that the "WithMany" will be "b.Posts"? Mine autofilled as well, but I don't understand how it knows, considering that it only mentioned the class Post, not the class Blog

Angius•2y ago

.HasOne(p => p.Blog) returns something that contains the information about what type the p.Blog is Then, .WithMany(b => b.Posts) uses that information, that type is the b there

Accord•2y ago

Was this issue resolved? If so, run /close - otherwise I will mark this as stale and this post will be archived until there is new activity.

Marcoelho97OP•2y ago

I see, that makes a lot of sense! Thank you so much!!! ♥

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✅ Multiple one to many relationships