Entity Framework complains that there is no primary key

Question

using System;

using System.Collections.Generic;

using System.ComponentModel.DataAnnotations;

namespace WpfApp6.Models;

public partial class Product

[Key]

public int IdProduct { get; set; }

public string NameOfProduct { get; set; } = null!;

public virtual ICollection<Purchase> Purchases { get; set; } = new List<Purchase>();
```}

 internal class ProductRepository : DbContext

 {

```typescript
 public DbSet<Product> Products { get; set; } = null!;

 public ProductRepository() => Database.EnsureCreated();

 protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)

 {

     optionsBuilder.UseMySql("server=127.0.0.1;port=3306;user=******;password=******;database=Shop",

         ServerVersion.AutoDetect("server=127.0.0.1;port=3306;user=******;password=******;database=Shop"));

 }

 public List<Product> GetProducts()

 {

     return Products.ToList();

 }

public partial class ShopContext : DbContext

public ShopContext()

{

}

public ShopContext(DbContextOptions<ShopContext> options)

    : base(options)

{

}

public virtual DbSet<Product> Products { get; set; }

public virtual DbSet<Purchase> Purchases { get; set; }

protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)

    => optionsBuilder.UseMySql("server=127.0.0.1;port=3306;user=******;password=******;database=Shop", ServerVersion.Parse("9.0.0-mysql"));

protected override void OnModelCreating(ModelBuilder modelBuilder)

{

    modelBuilder

        .UseCollation("utf8mb4_0900_ai_ci")

        .HasCharSet("utf8mb4");

    modelBuilder.Entity<Product>(entity =>

    {

        entity.HasKey(e => e.IdProduct).HasName("PRIMARY");

        entity.ToTable("product");

        entity.Property(e => e.IdProduct).HasColumnName("idProduct");

        entity.Property(e => e.NameOfProduct)

            .HasMaxLength(45)

            .HasColumnName("nameOfProduct");

    });

    modelBuilder.Entity<Purchase>(entity =>

    {

        entity.HasKey(e => e.IdPurchase).HasName("PRIMARY");

        entity.ToTable("purchase");

        entity.HasIndex(e => e.IdProduct, "idProduct_idx");

        entity.Property(e => e.IdPurchase).HasColumnName("idPurchase");

        entity.Property(e => e.DateOfPurchase).HasColumnName("dateOfPurchase");

        entity.Property(e => e.IdProduct).HasColumnName("idProduct");

        entity.Property(e => e.QuantityOfPurchases).HasColumnName("quantityOfPurchases");

        entity.Property(e => e.TotalCost)

            .HasPrecision(10, 2)

            .HasColumnName("totalCost");

        entity.HasOne(d => d.IdProductNavigation).WithMany(p => p.Purchases)

            .HasForeignKey(d => d.IdProduct)

            .HasConstraintName("idProduct");

    });

    OnModelCreatingPartial(modelBuilder);

}

partial void OnModelCreatingPartial(ModelBuilder modelBuilder);

public partial class MainWindow : Window

public MainWindow()

{

    InitializeComponent();

    ProductRepository productRepository = new() ;

    List <Product> products=productRepository.GetProducts();

}

private void Button_AddProducts(object sender, RoutedEventArgs e)

{

    DirectoryOfProducts directoryOfProducts = new DirectoryOfProducts();

    directoryOfProducts.Show();

}

Hello. I'm writing an application in wpf, for the first time I connected Entity Framework and MySQL. I created the database myself, after which Entity Framework built the classes itself. I wanted to display product values from a table. But an error appears - there is no primary key. Where did I make a mistake? Why does this happen and how to correctly register CRUD operations. This is my first time practicing Entity Framework

Answer 1

Hi,@vitaminchik. Welcome to Microsoft Q&A. 

Reason: Primary key constraint name is duplicated.

In ShopContext, when defining the primary key of the Product and Purchase tables.

entity.HasKey(e => e.IdProduct).HasName("PRIMARY");

entity.HasKey(e => e.IdPurchase).HasName("PRIMARY");

The primary key constraint name defined by HasName is repeated.

 

Solution: Modify the primary key constraint names of the database and EF to make them different.

 

Attach: The ProductRepositor you defined doesn't seem to make sense and will throw an error at runtime.

 

You could use ShopContext to manipulate data directly. You could refer to the following methods:

ShopContext shopContext = new ShopContext();

var list1 = shopContext.Purchases.ToList();

var list2 = shopContext.Products.ToList();

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