使用多重映射API时，如果您具有Id”，“ splitOn”以外的键且具有多重关系，请确保设置splitOn参数

Question

当我尝试执行此方法时，出现以下异常：

使用多重映射API时，如果您拥有ID以外的其他键，请确保设置splitOn参数

---

public static IEnumerable<FinancePositionList> GetFinancialListsForConsecutiveYears(int year, int periodTypeId, int period)
        {
            IEnumerable<FinancePositionList> resultList;
            using (var conn = new SqlConnection(ConfigurationManager.ConnectionStrings["Finance"].ConnectionString))
            {
                conn.Open();
                StringBuilder query = new StringBuilder();
                query.Append("SELECT b.CompanyId,b.CompanyName,[Year]");
                query.Append(",CreationDate,AccruedExpenses,AdvancePaymentsToContractors");


                query.Append("FROM finance.FinanceList a INNER JOIN finance.Company b ");
                query.Append("ON a.CompanyId = b.CompanyId ");
                query.Append("INNER JOIN finance.ListPeriod c ");
                query.Append("ON c.FinanceListId = a.FinanceListId ");
                query.Append("WHERE Discriminator = " + "'" + "FinancePositionList" + "' ");
                query.Append("AND[Year] IN @years ");
                query.Append("AND c.PeriodTypeId = @PeriodTypeId AND c.Period = @Period ");
                query.Append("ORDER BY b.CompanyId, a.[Year] DESC ");

                resultList = conn.Query<FinancePositionList, Company,ListPeriod, FinancePositionList>(query.ToString(),
                   (a, b,c) =>
                   {
                       a.Company = b;
                       c.FinanceList = a;
                       return a;
                   },
                  new
                  {
                      years = new[] { year, year - 1 },
                      PeriodTypeId = periodTypeId,
                      Period = period
                  },
                    splitOn: "CompanyId,FinanceListId").AsEnumerable();
            }
            return resultList;
        }

---

---

编辑：

我现在通过更改像这样的列顺序来解决此问题：但是我想知道是否可以对代码进行更多增强？

 public static IEnumerable<FinancePositionList> GetFinancialListsForConsecutiveYears(int year, int periodTypeId, int period)
        {
            IEnumerable<FinancePositionList> resultList;
            using (var conn = new SqlConnection(ResolveConnectionString()))
            {
                conn.Open();
                StringBuilder query = new StringBuilder();
                query.Append("SELECT CreationDate,AccruedExpenses,AdvancePaymentsToContractors,[Year]");
                query.Append(",b.CompanyId,b.CompanyName,c.FinanceListId ");
                query.Append("FROM finance.FinanceList a INNER JOIN finance.Company b ");
                query.Append("ON a.CompanyId = b.CompanyId ");
                query.Append("INNER JOIN finance.ListPeriod c ");
                query.Append("ON c.FinanceListId = a.FinanceListId ");
                query.Append("WHERE Discriminator = " + "'" + "FinancePositionList" + "' ");
                query.Append("AND [Year] IN @years ");
                query.Append("AND c.PeriodTypeId = @PeriodTypeId AND c.Period = @Period ");
                query.Append("ORDER BY b.CompanyId, a.[Year] DESC ");

                resultList = conn.Query<FinancePositionList, Company, ListPeriod, FinancePositionList>(query.ToString(),
                   (a, b, c) =>
                   {
                       a.Company = b;
                       a.CompanyId = b.CompanyId;
                       a.FinanceListId = c.FinanceListId;
                       return a;
                   },
                  new
                  {
                      years = new[] { year, year - 1 },
                      PeriodTypeId = periodTypeId,
                      Period = period
                  },
                    splitOn: "CompanyId,FinanceListId").AsEnumerable();
            }
            return resultList;
        }

Answer 1

您大多数人误解了Multimappingusing 的工作方式Dapper，您的查询产生了以下列：

**"CompanyId","CompanyName","Year","CreationDate","AccruedExpenses",
"AdvancePaymentsToContractors"**

现在，在multimapping代码中，以下是Query您正在调用的dapper 重载（从中检查source code）：

public static IEnumerable<TReturn> Query<TFirst, TSecond, TThird, TReturn>(
this IDbConnection cnn, string sql, Func<TFirst, TSecond, TThird, TReturn> map, 
object param, IDbTransaction transaction, bool buffered, string splitOn, 
int? commandTimeout, CommandType? commandType)

之前我误解了整个调用，但是现在看来，问题只在于使用SplitOn的Multi映射类型映射，您已经对其进行了更正，因此，只要spliton查询结果中提供了正确的列，以下操作就可以了

conn.Query<FinancePositionList, Company,ListPeriod, FinancePositionList>(query.ToString(), (a, b,c) =>
                   {
                       a.Company = b;
                       c.FinanceList = a;
                       return a;
                   },
                  new
                 {
                    years = new[] { year, year - 1 },
                    PeriodTypeId = periodTypeId,
                    Period = period
                 }, splitOn: "CompanyId,FinanceListId")

现在，只有一点需要澄清，因为我已经在评论中发布了years参数的integer array工作原理，该参数主要是an ，对于所有文本的当前查询来说，这都可以正常工作，但是对于stored procedures，它希望使用相同DataTable，与集合相同的列的顺序和名称只能使用来提供Table Valued Parameters。我不希望对当前用例进行任何其他更改。

编辑以提供匿名参数和动态参数的示例：

匿名参数

C＃中的这种简单匿名类型，请在此处检查，想法是您可以使用简单的占位符提供所有参数，例如{max = <value>,min=<value>}，即使名称匹配{max,min}，也可以按原样提供，在两种情况下参数均为@maxand @min，大小写无关紧要，请使用 AnonymousParametersin您的参数代码years, PeriodTypeId, Period，它将在内部推导类型和其他详细信息，并假定所有都是输入参数

{years = new[] { year, year - 1 },PeriodTypeId = periodTypeId,Period = period}

动态参数

它们更像是Ado.Net中的Parameter类，可让您显式添加参数，以下是Dapper代码中的重载，您必须Type, Direction显式提供诸如etc等的所有信息（dapper源代码中的代码段）：

public partial class DynamicParameters : SqlMapper.IDynamicParameters, SqlMapper.IParameterLookup, SqlMapper.IParameterCallbacks
    {
    public void Add(string name, object value, DbType? dbType, ParameterDirection? direction, int? size)

    public void Add(string name, object value = null, DbType? dbType = null, ParameterDirection? direction = null, int? size = null, byte? precision = null, byte? scale = null)
    }