C#•2mo ago

✅ Problem connecting entities on efcore

I'm new with blazor and efcore and i'm in trouble to connect 2 relation Error: ---> Npgsql.PostgresException (0x80004005): 23505: Duplicate key value violates unique constraint "PK_Blocks" Method:

    public async Task AddPaletteAsync(Database.Palette palette, ApplicationUser user)
    {
        await using var context = await dbContextFactory.CreateDbContextAsync();
        
        palette.UserId = user.Id;
        context.Palettes.Add(palette);
        await context.SaveChangesAsync();
    }

    public async Task AddPaletteAsync(Database.Palette palette, ApplicationUser user)
    {
        await using var context = await dbContextFactory.CreateDbContextAsync();
        
        palette.UserId = user.Id;
        context.Palettes.Add(palette);
        await context.SaveChangesAsync();
    }

18 Replies

Jimmacle•2mo ago

the error is saying that youre trying to insert an entity with a primary key value that another entity in the table already has

LuluhOP•2mo ago

im trying to create a new palette on db and connect blocks from another table to the palette, but it looks the db is trying to create another blocks insteaded connect

public class DatabaseContext(DbContextOptions<DatabaseContext> options, IConfiguration config) : IdentityDbContext<ApplicationUser>(options)
{
    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder) => optionsBuilder.UseNpgsql(config["Database:ConnectionString"]);

    public DbSet<Block> Blocks { get; set; }
    public DbSet<Palette> Palettes { get; set; }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        base.OnModelCreating(modelBuilder);

        modelBuilder.Entity<Block>()
            .HasIndex(b => b.MinecraftId)
            .IsUnique();

        modelBuilder.Entity<Palette>()
            .HasMany(p => p.Blocks)
            .WithMany(b => b.Palettes)
            .UsingEntity(j => j.ToTable("PaletteBlocks"));

        modelBuilder.Entity<Palette>()
            .HasOne(p => p.PlaceholderBlock)
            .WithMany()
            .HasForeignKey(p => p.PlaceholderBlockId)
            .OnDelete(DeleteBehavior.Restrict);

        modelBuilder.Entity<ApplicationUser>()
            .HasMany(u => u.Palettes)
            .WithOne(p => p.User)
            .HasForeignKey(p => p.UserId);
        
        modelBuilder.Entity<IdentityUserLogin<string>>(entity =>
        {
            entity.HasKey(l => new { l.LoginProvider, l.ProviderKey });
        });

        modelBuilder.Entity<IdentityUserRole<string>>(entity =>
        {
            entity.HasKey(r => new { r.UserId, r.RoleId });
        });

        modelBuilder.Entity<IdentityUserToken<string>>(entity =>
        {
            entity.HasKey(t => new { t.UserId, t.LoginProvider, t.Name });
        });
    }
}

public class DatabaseContext(DbContextOptions<DatabaseContext> options, IConfiguration config) : IdentityDbContext<ApplicationUser>(options)
{
    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder) => optionsBuilder.UseNpgsql(config["Database:ConnectionString"]);

    public DbSet<Block> Blocks { get; set; }
    public DbSet<Palette> Palettes { get; set; }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        base.OnModelCreating(modelBuilder);

        modelBuilder.Entity<Block>()
            .HasIndex(b => b.MinecraftId)
            .IsUnique();

        modelBuilder.Entity<Palette>()
            .HasMany(p => p.Blocks)
            .WithMany(b => b.Palettes)
            .UsingEntity(j => j.ToTable("PaletteBlocks"));

        modelBuilder.Entity<Palette>()
            .HasOne(p => p.PlaceholderBlock)
            .WithMany()
            .HasForeignKey(p => p.PlaceholderBlockId)
            .OnDelete(DeleteBehavior.Restrict);

        modelBuilder.Entity<ApplicationUser>()
            .HasMany(u => u.Palettes)
            .WithOne(p => p.User)
            .HasForeignKey(p => p.UserId);
        
        modelBuilder.Entity<IdentityUserLogin<string>>(entity =>
        {
            entity.HasKey(l => new { l.LoginProvider, l.ProviderKey });
        });

        modelBuilder.Entity<IdentityUserRole<string>>(entity =>
        {
            entity.HasKey(r => new { r.UserId, r.RoleId });
        });

        modelBuilder.Entity<IdentityUserToken<string>>(entity =>
        {
            entity.HasKey(t => new { t.UserId, t.LoginProvider, t.Name });
        });
    }
}

My DB

public class Block
{
    public Guid Id { get; set; } = Guid.CreateVersion7();
    public string MinecraftId { get; set; }
    public int MapId { get; set; }
    public string? ImageUrl { get; set; }

    public Dictionary<string, string> Properties { get; set; } = new();
    public Dictionary<string, string> GeneratorProperties { get; set; } = new();

    public List<Palette> Palettes { get; set; } = [];
}

public class Palette
{
    public Guid Id { get; set; } = Guid.NewGuid();
    public string Name { get; set; }

    public Guid PlaceholderBlockId { get; set; }
    public Block PlaceholderBlock { get; set; }

    public List<Block> Blocks { get; set; } = [];

    public string UserId { get; set; }
    public ApplicationUser User { get; set; }
}

public class ApplicationUser : IdentityUser
{
    public List<Palette> Palettes { get; set; } = [];
}

public class Block
{
    public Guid Id { get; set; } = Guid.CreateVersion7();
    public string MinecraftId { get; set; }
    public int MapId { get; set; }
    public string? ImageUrl { get; set; }

    public Dictionary<string, string> Properties { get; set; } = new();
    public Dictionary<string, string> GeneratorProperties { get; set; } = new();

    public List<Palette> Palettes { get; set; } = [];
}

public class Palette
{
    public Guid Id { get; set; } = Guid.NewGuid();
    public string Name { get; set; }

    public Guid PlaceholderBlockId { get; set; }
    public Block PlaceholderBlock { get; set; }

    public List<Block> Blocks { get; set; } = [];

    public string UserId { get; set; }
    public ApplicationUser User { get; set; }
}

public class ApplicationUser : IdentityUser
{
    public List<Palette> Palettes { get; set; } = [];
}

palette and blocks is a many to many relation

Unknown User•2mo ago

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LuluhOP•2mo ago

still having issues, i think the problem is not related with keys

Unknown User•2mo ago

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LuluhOP•2mo ago

nope, this problem is occuring because im trying to insert the palette on another dbcontext that i get the blocks, so the blocks is no more tracked by the dbcontext and the efcore tries to create a new block insteaded connect with the palette

Unknown User•2mo ago

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LuluhOP•2mo ago

thats the error

Unknown User•2mo ago

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LuluhOP•2mo ago

i alread fixed that .

Unknown User•2mo ago

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Jimmacle•2mo ago

tebe i don't think this is helping @Luluh yes, if you are moving entities between dbcontext instances it will cause problems with tracking and it will think existing entities are new ones if you want it to work like this you'll need to inform the change tracker that the entities are updated, not new

Unknown User•2mo ago

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LuluhOP•2mo ago

yees, i fixed this initializing the dbcontext on the page instead reinitialize in every method on the service i think the db was trying to create the blocks again because the blocks were not being tracked

Unknown User•2mo ago

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LuluhOP•2mo ago

because im getting error when multiple instances are running and quering the db in same time

Unknown User•2mo ago

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MODiX•2mo ago

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✅ Problem connecting entities on efcore