Dapper - 使用除 Id 之外的分割点的多重映射

Question

我知道这类似于 正确使用 Dapper 中的多重映射，但我认为略有不同。

我有以下 POCO 结构：

public class Customer
{
    public int customerkey { get; set; }
    public string FirstName { get; set; }
    public string LastName { get; set; }
    public string EmailAddress { get; set; }
    public List<Invoice> Invoices { get; set; }
    public int statekey { get; set; }
    public State State { get; set; }

    public Customer()
    {
        this.Invoices = new List<Invoice>();
    }
}

public class Invoice
{
    public int customerinvoicekey { get; set; }
    public int customerkey { get; set; }
    public int Number { get; set; }
    public string Description { get; set; }
    public int Total { get; set; }
    public int statuskey { get; set; }
    public State State { get; set; }
}

public class State
{   
    public int statekey { get; set; }
    public string Description { get; set; }
}

我正在尝试使用 Dapper 来映射它，并且我没有使用 Id 作为分割点。如果我将密钥加倍，我就可以让它工作，但我不确定为什么我必须这样做。

为什么这有效：

const string commandText =
        @"SELECT 
        A.customerkey, A.FirstName, A.LastName, A.EmailAddress, A.statuskey,
        C.statuskey, C.Description,
        B.customerinvoicekey, B.customerkey, B.Number, B.Description, B.Total, B.statuskey,
        D.statuskey, D.Description
        FROM Web.TestCustomers2 A
        INNER JOIN Web.TestCustomerInvoices2 B ON A.customerkey = B.customerkey
        INNER JOIN Web.TestStatus2 C ON A.statuskey = C.statuskey
        INNER JOIN Web.TestStatus2 D ON B.statuskey = D.statuskey
        ORDER BY A.customerkey";

        var customers = new List<Customer>();
        Customer currentCustomer = null;
        db.Connection.Query<Customer, State, Invoice, State, Customer>(commandText,
            (customer, customerstate, invoice, invoicestate) =>
            {
                if (currentCustomer == null || currentCustomer.customerkey != customer.customerkey)
                {
                    customers.Add(customer);
                    currentCustomer = customer;
                }
                invoice.State = invoicestate;
                currentCustomer.Invoices.Add(invoice);
                currentCustomer.State = customerstate;
                return currentCustomer;
            }, splitOn: "statuskey,customerinvoicekey,statuskey");

但这不起作用（忽略 A 和 B 中 statuskey 的选择）：

const string commandText =
        @"SELECT 
        A.customerkey, A.FirstName, A.LastName, A.EmailAddress,
        C.statuskey, C.Description,
        B.customerinvoicekey, B.customerkey, B.Number, B.Description, B.Total,
        D.statuskey, D.Description
        FROM Web.TestCustomers2 A
        INNER JOIN Web.TestCustomerInvoices2 B ON A.customerkey = B.customerkey
        INNER JOIN Web.TestStatus2 C ON A.statuskey = C.statuskey
        INNER JOIN Web.TestStatus2 D ON B.statuskey = D.statuskey
        ORDER BY A.customerkey";

        var customers = new List<Customer>();
        Customer currentCustomer = null;
        db.Connection.Query<Customer, State, Invoice, State, Customer>(commandText,
            (customer, customerstate, invoice, invoicestate) =>
            {
                if (currentCustomer == null || currentCustomer.customerkey != customer.customerkey)
                {
                    customers.Add(customer);
                    currentCustomer = customer;
                }
                invoice.State = invoicestate;
                currentCustomer.Invoices.Add(invoice);
                currentCustomer.State = customerstate;
                return currentCustomer;
            }, splitOn: "statuskey,customerinvoicekey,statuskey");

Answer 1

customerinvoicekey 到底来自哪里？

您的模型声称该表的键是 public int customerkey { get;放; }。

如果您在模型中不存在的列上进行拆分，则多重映射函数的行为是未定义的。