Question

当我尝试着先使用Entity Framework代码以及如何设置实体之间的关系时。当我尝试向数据库中插入（种子）某些数据时遇到了一个问题。我试图将一个产品对象插入到buys（订单）对象中。所购买的产品属性是虚拟的，表明它是导航属性。有没有其他方法可以达到我想要的目标？

我运行Add-Migration initial并收到错误消息：

无法添加实体类型“购买”的种子实体，因为它已设置了导航“客户”。要播种关系，您需要将相关实体种子添加到“客户”并指定外键值{'customerID'}。考虑使用'DbContextOptionsBuilder.EnableSensitiveDataLogging'查看所涉及的属性值

下面是在数据上下文类中运行的种子方法。

private void SeedDatabase(ModelBuilder builder)
{
        // Construct Data
        var productType = new ProductType()
        {
            typeName = "Operating System"
        };

        var product = new Product()
        {
            typeID = productType.typeID,
            productName = "Windows",
            productVersion = "10 Home",
            productDescription = "This version of windows is the Home 10 edition",
            keyPrice = 10,
            license = "ASDEW-2342-SDE34-FGR35",
            ProductType = productType
        };

        var customer = new Customer()
        {
            customerEmail = "test-customer@gmail.com",
            customerFullname = "John Derek"
        };

        var transaction = new Transaction()
        {
            paid = true,
            transactionAmount = 10
        };

        var order = new Buys()
        {
            customerID = customer.customerID,
            TransactionID = transaction.transcationID,
            quantity = 1,
            Date = new DateTime().Date,
            Transaction = transaction,
            Customer = customer,
            Product = product,
            productID = product.productID
        };

        transaction.Buy = order;
        System.Collections.Generic.List<Buys> orders = new System.Collections.Generic.List<Buys>() { order };
        product.customerBuys = orders;

        builder.Entity<ProductType>()
            .HasData(productType);

        builder.Entity<Product>()
           .HasData(product);

        builder.Entity<Customer>()
           .HasData(customer);

        builder.Entity<Transaction>()
           .HasData(transaction);

        builder.Entity<Buys>()
           .HasData(orders);
    }

这是要提到的两个模型。

public class Customer
{
    public Customer()
    {
        customerID = Guid.NewGuid().ToString();
    }

    [Key]
    public string customerID { get; set; }
    public string customerFullname { get; set; }
    public string customerEmail { get; set; }
    public virtual ICollection<Buys> customerBuys { get; set; }
}

// This is a join table between product and customer.
// Product can have many customers
// One customer can purchase many products
public class Buys
{
    public Buys()
    {
        buyID = Guid.NewGuid().ToString();
    }

    [Key]
    public string buyID { get; set; }
    public string productID { get; set; }
    public virtual Product Product { get; set; }
    public string customerID { get; set; }
    public virtual Customer Customer { get; set; }
    public int quantity { get; set; }
    public DateTime Date { get; set; }
    public string TransactionID { get; set; }
    public virtual Transaction Transaction { get; set; }
}

Answer 1

Id字段是字符串，您不会在任何地方填充它们。在将对象传递给HasData（）之前，尝试为这些ID播种。

示例：

var productType = new ProductType()
{
    Id = Guid.NewGuid().ToString(), //If they are supposed to be GUIDs
    typeName = "Operating System"
};

实体框架不会建立实体关系

1 个答案: