C#•2y ago

❔ Unique Constraint Failed EF core

Hi, i tried to add a new program bending with a userId but I've this following error and i do not understand why because in my database i didn't set unique value for the UserId even if it is an foreign key

19 Replies

ElioOP•2y ago

should i add this in my User model ?

FusedQyou•2y ago

Are you using migrations?

ElioOP•2y ago

yes

FusedQyou•2y ago

I believe it will be fixed if you make the foreign key id nullable. I assume you want to make the relation optional? Right now ProgramBendings probably has a foreign key defined that is required. It is therefore required that it has a relation to User

ElioOP•2y ago

ye but the fact was that the foreign key specified was correct but for no reason i can't assigned the same userId to different ProgramBending currently i try to redo the migrations to be sure nothing was missing

FusedQyou•2y ago

Are you manually assigning the id? Is it possible to get the related user and storing the reference in the actual user class properly of ProgramBending? Modern EF does not even need the foreign key specified, just the class. It will do the rest for you

ElioOP•2y ago

nop i do not set the userid manually are you sure ? cause to me if i set the entity in programBending for example, it will try to create a new User entity in the database am i wrond ?

FusedQyou•2y ago

It will do that if EF is not tracking that user. If you added the user in EF, or you retrieved it from the database, it will be tracked. Otherwise it creates a new one and tracks it

ElioOP•2y ago

hum ok i wasn't aware of this thanks

FusedQyou•2y ago

EF has a whole change tracking system which is not really explained a lot

ElioOP•2y ago

i still have the problem even with a nullable foreign key

FusedQyou•2y ago

Did you make a new migration? It should explicitly remove the "required" part

ElioOP•2y ago

i did it and the fact is i didn't set UserId to be unique here my classes :

 [Table("ProgramBending")]
    public class ProgramBending
    {
        [Key]
        public long Id { get; set; }
        [Required]
        public string Name { get; set; } = null!; 

        public long? UserId { get; set; }
        public User? User { get; set; } = null!;

        public long? ThicknessId { get; set; }
        public Thickness? Thickness { get; set; } = null!;
        public Template Template { get; set; } = null!;
        public DataProgram DataProgram { get; set; } = null!;
}

 [Table("ProgramBending")]
    public class ProgramBending
    {
        [Key]
        public long Id { get; set; }
        [Required]
        public string Name { get; set; } = null!; 

        public long? UserId { get; set; }
        public User? User { get; set; } = null!;

        public long? ThicknessId { get; set; }
        public Thickness? Thickness { get; set; } = null!;
        public Template Template { get; set; } = null!;
        public DataProgram DataProgram { get; set; } = null!;
}

 
[Table("User")]
    public class User
    {

        [Key]
        public long Id { get; set; }
        public string Name { get; set; } = null!;
        public string UserName { get; set; } = null!;
        public string HashPassword { get; set; } = null!;

        public EnumUserRole UserRole { get; set; }
        public EnumUserState UserState { get; set; } = EnumUserState.Offline;

        public EnumLanguage Language { get; set; } = EnumLanguage.FR;
}

 
[Table("User")]
    public class User
    {

        [Key]
        public long Id { get; set; }
        public string Name { get; set; } = null!;
        public string UserName { get; set; } = null!;
        public string HashPassword { get; set; } = null!;

        public EnumUserRole UserRole { get; set; }
        public EnumUserState UserState { get; set; } = EnumUserState.Offline;

        public EnumLanguage Language { get; set; } = EnumLanguage.FR;
}

oh i think i've understand, perhaps i've forgot to add the relation between user and programbending in OnModelCreating

FusedQyou•2y ago

EF should do that automatically

ElioOP•2y ago

ok here was my problem i found it 😄 i prefere to do it myself to be sure there is no problem in the relation between my classes

FusedQyou•2y ago

Makes sense

ElioOP•2y ago

modelBuilder.Entity<ProgramBending>()
               .HasOne(p => p.User)
               .WithMany()
               .HasForeignKey(p => p.UserId)
               .OnDelete(DeleteBehavior.NoAction);

here was the missing part 😄 thanks for your help i was able to found my problem 😁

FusedQyou•2y ago

Did you know that this can also be achieved with an attribute? https://www.entityframeworktutorial.net/code-first/foreignkey-dataannotations-attribute-in-code-first.aspx

DataAnnotations - ForeignKey Attribute in EF 7 & EF Core

Learn about the [ForeignKey] DataAnnotation attribute in EF 6 and EF Core Code-First approach.

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.

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❔ Unique Constraint Failed EF core