Question

继续运行“如果使用多映射API，请确保在下面的代码块中出现错误以外的其他密钥时设置splitOn参数”：

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 for splitOn作为解决方法。

我错过了什么？

由于

修改

我已经清理了一下我的测试，下面是一个轻量级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();

Answer 1

经过几个小时的Dapper源代码调试后，我终于找到了问题并且非常有趣。

当提供多个splitOn字段时，Dapper会根据逗号进行拆分，例如： var splits = splitOn.Split（'，'）。ToArray（）。然后它循环遍历所有记录集字段，并根据上面的数组将它们拆分为对象;漂亮的海峡前进。

现在有趣的部分：当我提供我的splitOn字段时，我在逗号之后有一个额外的SPACE，例如“AccountId，BranchId”和那个小空间是原因。在Split（）之后，BranchId字段包含一个额外的空格，并且无法与记录集中的任何字段匹配。

有两种解决方法：

逗号后不要使用额外的空格;我个人上瘾至; SQL的旧习惯。
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;这就是我为我的本地副本所做的。

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

以上修复已合并：https://github.com/SamSaffron/dapper-dot-net/commit/399db17e5aa6f1eefaf8fdccff827020be8e6cbb

精巧的多映射问题

1 个答案: