C#•9mo ago

Entity framework exception while creating a many to many relation

Hello everyone, I've been trying to make a many to many relation between two classes Voyage and Transporteur. these are the Three classes:

c#
public class Transporteur : IdentityUser
    {
        public string Nom { get; set; } = string.Empty;
        public string Prenom { get; set; } = string.Empty;

        public Vehicule? Vehicule { get; set; }
        public string? VehiculeId { get; set; } = string.Empty;
        public bool ExterneDuService { get; set; } = false;
        public List<Voyage> Voyages { get; } = [];
        public ICollection<TransporteurVoyage> TransporteurVoyages { get; } = [];
    }
****************************************************
public class Voyage
    {
        [Key]
        public string IdVoyage { get; set; } = string.Empty;
        public DateTime DateSortieBon { get; set; }
        public DateTime DateDepartVoyage { get; set; }

        public string Etat { get; set; } = string.Empty;
        //Demandeur
        public Demandeur Demandeur { get; set; } = null!;
        public string DemandeurId { get; set; } = string.Empty;
        //public ICollection<Utilisateur> Utilisateurs { get; set; } = new List<Utilisateur>();
        public Magasinier Magasinier { get; set; } = null!;
        public string IdMagasinier { get; set; } = string.Empty;
        public TypeVoyage TypeVoyage { get; set; } = null!;
        public int TypeVoyageId { get; set; }
        public List<Transporteur> Transporteurs { get; } = [];
        public ICollection<TransporteurVoyage> TransporteurVoyages { get; } = [];


    }
********************************************************************
public class TransporteurVoyage
    {
        public string TransporteurId { get; set; } = string.Empty;
        public string VoyageId { get; set; } = string.Empty;
        public bool Panne { get; set; } = false;
        public Voyage Voyage { get; set; } 
        public Transporteur Transporteur { get; set; }

    }

c#
public class Transporteur : IdentityUser
    {
        public string Nom { get; set; } = string.Empty;
        public string Prenom { get; set; } = string.Empty;

        public Vehicule? Vehicule { get; set; }
        public string? VehiculeId { get; set; } = string.Empty;
        public bool ExterneDuService { get; set; } = false;
        public List<Voyage> Voyages { get; } = [];
        public ICollection<TransporteurVoyage> TransporteurVoyages { get; } = [];
    }
****************************************************
public class Voyage
    {
        [Key]
        public string IdVoyage { get; set; } = string.Empty;
        public DateTime DateSortieBon { get; set; }
        public DateTime DateDepartVoyage { get; set; }

        public string Etat { get; set; } = string.Empty;
        //Demandeur
        public Demandeur Demandeur { get; set; } = null!;
        public string DemandeurId { get; set; } = string.Empty;
        //public ICollection<Utilisateur> Utilisateurs { get; set; } = new List<Utilisateur>();
        public Magasinier Magasinier { get; set; } = null!;
        public string IdMagasinier { get; set; } = string.Empty;
        public TypeVoyage TypeVoyage { get; set; } = null!;
        public int TypeVoyageId { get; set; }
        public List<Transporteur> Transporteurs { get; } = [];
        public ICollection<TransporteurVoyage> TransporteurVoyages { get; } = [];


    }
********************************************************************
public class TransporteurVoyage
    {
        public string TransporteurId { get; set; } = string.Empty;
        public string VoyageId { get; set; } = string.Empty;
        public bool Panne { get; set; } = false;
        public Voyage Voyage { get; set; } 
        public Transporteur Transporteur { get; set; }

    }

23 Replies

daminkoOP•9mo ago

This is my dbContext:

c#
 public class ApplicationDBContext : IdentityDbContext<IdentityUser>
    {
        public ApplicationDBContext(DbContextOptions dbContextOptions) : base(dbContextOptions)
        {
        }
        public DbSet<Entrepot> Entrepot { get; set; }

        public DbSet<Admin> Admin { get; set; }
        public DbSet<Magasinier> Magasinier { get; set; }
        public DbSet<Transporteur> Transporteur { get; set; }
        public DbSet<TransporteurVoyage> TransporteurVoyage { get; set; }
        public DbSet<Demandeur> Demandeur { get; set; }
        public DbSet<Vehicule> Vehicule { get; set; }


        protected override void OnModelCreating(ModelBuilder builder)
        {
            base.OnModelCreating(builder);
            builder.Entity<TransporteurVoyage>().HasKey(t => new { t.TransporteurId, t.VoyageId });
            
            builder.Entity<IdentityRole>().HasData(roles);
            builder.Entity<TransporteurVoyage>()
                  .HasKey(pc => new { pc.TransporteurId, pc.VoyageId });
            builder.Entity<TransporteurVoyage>()
                    .HasOne(p => p.Voyage)
                    .WithMany(pc => pc.TransporteurVoyages)
                    .HasForeignKey(p => p.VoyageId);
            builder.Entity<TransporteurVoyage>()
                    .HasOne(p => p.Transporteur)
                    .WithMany(pc => pc.TransporteurVoyages)
                    .HasForeignKey(c => c.TransporteurId);
        }
    }

c#
 public class ApplicationDBContext : IdentityDbContext<IdentityUser>
    {
        public ApplicationDBContext(DbContextOptions dbContextOptions) : base(dbContextOptions)
        {
        }
        public DbSet<Entrepot> Entrepot { get; set; }

        public DbSet<Admin> Admin { get; set; }
        public DbSet<Magasinier> Magasinier { get; set; }
        public DbSet<Transporteur> Transporteur { get; set; }
        public DbSet<TransporteurVoyage> TransporteurVoyage { get; set; }
        public DbSet<Demandeur> Demandeur { get; set; }
        public DbSet<Vehicule> Vehicule { get; set; }


        protected override void OnModelCreating(ModelBuilder builder)
        {
            base.OnModelCreating(builder);
            builder.Entity<TransporteurVoyage>().HasKey(t => new { t.TransporteurId, t.VoyageId });
            
            builder.Entity<IdentityRole>().HasData(roles);
            builder.Entity<TransporteurVoyage>()
                  .HasKey(pc => new { pc.TransporteurId, pc.VoyageId });
            builder.Entity<TransporteurVoyage>()
                    .HasOne(p => p.Voyage)
                    .WithMany(pc => pc.TransporteurVoyages)
                    .HasForeignKey(p => p.VoyageId);
            builder.Entity<TransporteurVoyage>()
                    .HasOne(p => p.Transporteur)
                    .WithMany(pc => pc.TransporteurVoyages)
                    .HasForeignKey(c => c.TransporteurId);
        }
    }

This is the exception:

Unable to create a 'DbContext' of type ''. The exception 'Cannot use table 'TransporteurVoyage' for entity type 'TransporteurVoyage' since it is being used for entity type 'TransporteurVoyage (Dictionary<string, object>)' and potentially other entity types, but there is no linking relationship. Add a foreign key to 'TransporteurVoyage' on the primary key properties and pointing to the primary key on another entity type mapped to 'TransporteurVoyage'.' was thrown while attempting to create an instance. For the different patterns supported at design time, see https://go.microsoft.com/fwlink/?linkid=851728

Unable to create a 'DbContext' of type ''. The exception 'Cannot use table 'TransporteurVoyage' for entity type 'TransporteurVoyage' since it is being used for entity type 'TransporteurVoyage (Dictionary<string, object>)' and potentially other entity types, but there is no linking relationship. Add a foreign key to 'TransporteurVoyage' on the primary key properties and pointing to the primary key on another entity type mapped to 'TransporteurVoyage'.' was thrown while attempting to create an instance. For the different patterns supported at design time, see https://go.microsoft.com/fwlink/?linkid=851728

Angius•9mo ago

I'd try configuring the join table with .UsingEntity()

daminkoOP•9mo ago

how?

Angius•9mo ago

https://learn.microsoft.com/en-us/ef/core/modeling/relationships/many-to-many#many-to-many-with-class-for-join-entity

builder.Entity<Transporteur>()
  .HasMany(t => t.Voyages)
  .WithMany(v => v.Transporteurs)
  .UsingEntity<TransporteurVoyage>(/* other config */);

builder.Entity<Transporteur>()
  .HasMany(t => t.Voyages)
  .WithMany(v => v.Transporteurs)
  .UsingEntity<TransporteurVoyage>(/* other config */);

daminkoOP•9mo ago

I've tried this to be more precise

c#
 builder.Entity<Transporteur>()
  .HasMany(t => t.Voyages)
  .WithMany(v => v.Transporteurs)
  .UsingEntity<TransporteurVoyage>(
     l => l.HasOne<Voyage>().WithMany().HasForeignKey(e => e.VoyageId),
            r => r.HasOne<Transporteur>().WithMany().HasForeignKey(e => e.TransporteurId)
  );

c#
 builder.Entity<Transporteur>()
  .HasMany(t => t.Voyages)
  .WithMany(v => v.Transporteurs)
  .UsingEntity<TransporteurVoyage>(
     l => l.HasOne<Voyage>().WithMany().HasForeignKey(e => e.VoyageId),
            r => r.HasOne<Transporteur>().WithMany().HasForeignKey(e => e.TransporteurId)
  );

but got another exception

Error Number:1785,State:0,Class:16
Introducing FOREIGN KEY constraint 'FK_TransporteurVoyage_Voyage_VoyageId' on table 'TransporteurVoyage' may cause cycles or multiple cascade paths. Specify ON DELETE NO ACTION or ON UPDATE NO ACTION, or modify other FOREIGN KEY constraints.
Could not create constraint or index. See previous errors.
Warning! The maximum key length for a clustered index is 900 bytes. The index 'PK_TransporteurVoyage' has maximum length of 1800 bytes. For some combination of large values, the insert/update operation will fail.

Error Number:1785,State:0,Class:16
Introducing FOREIGN KEY constraint 'FK_TransporteurVoyage_Voyage_VoyageId' on table 'TransporteurVoyage' may cause cycles or multiple cascade paths. Specify ON DELETE NO ACTION or ON UPDATE NO ACTION, or modify other FOREIGN KEY constraints.
Could not create constraint or index. See previous errors.
Warning! The maximum key length for a clustered index is 900 bytes. The index 'PK_TransporteurVoyage' has maximum length of 1800 bytes. For some combination of large values, the insert/update operation will fail.

daminkoOP•9mo ago

Angius•9mo ago

Why are the IDs 450-character long varchars

daminkoOP•9mo ago

The Transporteur inherits from IdentityUser

Angius•9mo ago

I'd change the type of the key it uses To a GUID or something

daminkoOP•9mo ago

How can I change it?

Angius•9mo ago

Because varchar IDs this long are a bad idea Transporteur : IdentityUser<TKey> TKey being the type of the key

daminkoOP•9mo ago

Angius•9mo ago

You'll need to recreate the migrations, mind you Or, well, at least create a new one Actually... you will need to drop the database, delete migrations, and create them from zero

daminkoOP•9mo ago

I'm still creating my database so np

Angius•9mo ago

Since PK change is not backwards compatible

daminkoOP•9mo ago

Just one more question

daminkoOP•9mo ago

I have these 4 classes that extends Utilisateur what I've done I created the Demandeur, Admin Magasinier and the transporteur classes all of them extends the IdentityUser is it a good approach? or there is a better one

Angius•9mo ago

IMHO the best approach would be to use roles, not inheritance in this case But, sure, inheritance should work as well

daminkoOP•9mo ago

my business logic imposes inheritance

Angius•9mo ago

Then you do what you must

daminkoOP•9mo ago

Tysm for your time

deem•9mo ago

no problem

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Entity framework exception while creating a many to many relation