Dapper多重映射问题

继续遇到以下代码块的“使用多重映射API时，如果您具有ID以外的键，请确保设置splitOn参数”错误:

var accounts = DbConnection.Query<Account, Branch, Application, Account>(
            "select Accounts.*, SplitAccount = '', Branches.*, SplitBranch = '', Applications.*" +
            " from Accounts" +
            "    join Branches" +
            "       on Accounts.BranchId = Branches.BranchId" +
            "    join Applications" +
            "       on Accounts.ApplicationId = Applications.ApplicationId" +
            " where Accounts.AccountId <> 0",
            (account, branch, application) =>
                {
                    account.Branch = branch;
                    account.Application = application;
                    return account;
                }, splitOn : "SplitAccount, SplitBranch"
            ).AsQueryable();

我正在使用SplitAccount和SplitBranch作为splitOn的解决方法。

我错过了什么吗？

谢谢

编辑:

我已经整理了一下测试，下面是一个简单的类和一个新的查询:

public class AccountLight
{
    public int AccountId { get; set; }
    public string AccountNumber { get; set; }
    public BranchLight Branch { get; set; }
    public ApplicationLight Application { get; set; }
}

public class BranchLight
{
    public int BranchId { get; set; }
    public string BranchNumber { get; set; }
}

public class ApplicationLight
{
    public int ApplicationId { get; set; }
    public string ApplicationCode { get; set; }
}

var accounts2 = DbConnection.Query<AccountLight, BranchLight, ApplicationLight, AccountLight>(
    "select Accounts.AccountId, Accounts.AccountNumber," +
    "       Branches.BranchId, Branches.BranchNumber," +
    "       Applications.ApplicationId, Applications.ApplicationCode" +
    " from Accounts" +
    "    inner join Branches" +
    "       on Accounts.BranchId = Branches.BranchId" +
    "    inner join Applications" +
    "       on Accounts.ApplicationId = Applications.ApplicationId" +
    " where Accounts.AccountId <> 0",
    (account, brach, application) =>
    {
        account.Branch = brach;
        account.Application = application;
        return account;
    },
    commandType: CommandType.Text,
    splitOn: "AccountId, BranchId"
    ).AsQueryable();

最佳答案

在调试了Dapper的源代码几个小时之后，我终于找到了这个问题，这很有趣。

提供多个splitOn字段时，Dapper会基于逗号进行拆分，例如var splits = splitOn.Split('，')。ToArray()。然后，它将遍历所有记录集字段，并根据上述数组将其拆分为对象；海峡前进。

现在最有趣的部分是:当我提供splitOn字段时，在逗号后有一个额外的空格，例如原因是“AccountId，BranchId”，这是很小的空间。在Split()之后，BranchId字段包含多余的空间，无法与记录集中的ANY字段匹配。

有两种解决方法:

请勿在逗号后使用多余的空格；我个人上瘾
至; SQL的一个旧习惯。

修改Dapper的GenerateDeserializers
方法和更改:var currentSplit =将[splitIndex]拆分为var
currentSplit = splits [splitIndex] .Trim()或类似的东西；这就是我为本地副本所做的。

这是代码快照:

    private static Func<IDataReader, object>[] GenerateDeserializers(Type[] types, string splitOn, IDataReader reader)
    {
        int current = 0;
        var splits = splitOn.Split(',').ToArray();
        var splitIndex = 0;

        Func<Type, int> nextSplit = type =>
        {
            var currentSplit = splits[splitIndex].Trim();
            if (splits.Length > splitIndex + 1)
            {
                splitIndex++;
            }

更新:

上面的修复程序已合并:https://github.com/SamSaffron/dapper-dot-net/commit/399db17e5aa6f1eefaf8fdccff827020be8e6cbb