Question

我的方案： 我有一个名为Person的类，我使用Dapper保存到DB。在Person上，我有一个值列表，我将其序列化为字符串并将其存储为varchar（MAX）。

public class Person
{
    public string Name {get; set;}
    public int Id {get; set;} //PK in DB
    public int Age {get; set;}
    public IDictionary<string, string> Values {get; set;}
}

这是我保存到数据库的方式：

DynamicProperties dp = new DynamicProperties();
dp.Add("Name", p.Name);
dp.Add("Age", p.Age);
dp.Add("Values",  Jil.JSON.Serialize<IDictionary<string, string>>(p.Values));

conneciton.Execute(insertSql, dp, commandType: CommandType.StoredProcedure);

这是我尝试阅读的地方

    private Func<Person, object, Person> GetPerson = new Func<Person, object, Person>
((person, values) => {
                person.Values = Jil.JSON.Deserialize<Dictionary<string, string>>((string)values);
                return person;
            });

string sql =   "SELECT text
                FROM otherTable

                SELECT Name, Id, Age, Values 
                FROM People 
                WHERE Id = @Id"

SqlMapper.GridReader gridReader = connToDeviceConfig.QueryMultiple(sql, new {Id = 5}, commandType: CommandType.StoredProcedure);

List<string> listOfOtherStuff = gridReader.Read<string>().ToList();
List<Person> people = gridReader.Read<Person, object, Person>(GetPerson, splitOn: "Age").ToList();

// listOfOtherStuff和人是分开的

第二个gridReader失败并显示当使用多映射API时，如果您拥有Id \ r \ n \ nParameter name以外的其他键，请确保设置splitOn参数：splitOn

我觉得我可能会弯曲Dapper尝试让它做一些它不应该做的事情，即读出一个字符串数据库并将其反序列化为字典并分配给Person.Values。

这是做到这一点的方式（我只是在某个地方有一个bug）？或者我应该采取另一种方法吗？

我用它作为参考： (Link to approximate location in file at Archive.org)

public void TestProcSupport()
{
    var p = new DynamicParameters();
    p.Add("a", 11);
    p.Add("b", dbType: DbType.Int32, direction: ParameterDirection.Output);
    p.Add("c", dbType: DbType.Int32, direction: ParameterDirection.ReturnValue);

    connection.Execute(@"create proc #TestProc 
@a int,
@b int output
as 
begin
set @b = 999
select 1111
return @a
end");
    connection.Query<int>("#TestProc", p, commandType: CommandType.StoredProcedure).First().IsEqualTo(1111);

    p.Get<int>("c").IsEqualTo(11);
    p.Get<int>("b").IsEqualTo(999);

}

堆栈跟踪：

   at Dapper.SqlMapper.GetNextSplit(Int32 startIdx, String splitOn, IDataReader reader) in D:\Dev\dapper-dot-net\Dapper NET40\SqlMapper.cs:line 2111
   at Dapper.SqlMapper.GenerateDeserializers(Type[] types, String splitOn, IDataReader reader) in D:\Dev\dapper-dot-net\Dapper NET40\SqlMapper.cs:line 2057
   at Dapper.SqlMapper.<MultiMapImpl>d__71`8.MoveNext() in D:\Dev\dapper-dot-net\Dapper NET40\SqlMapper.cs:line 1857
   at Dapper.SqlMapper.GridReader.<MultiReadInternal>d__9`8.MoveNext() in D:\Dev\dapper-dot-net\Dapper NET40\SqlMapper.cs:line 4300
   at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
   at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
   at Dapper.SqlMapper.GridReader.Read[TFirst,TSecond,TReturn](Func`3 func, String splitOn, Boolean buffered) in D:\Dev\dapper-dot-net\Dapper NET40\SqlMapper.cs:line 4330

Answer 1

尝试了其他splitOn s？

我没有方便的数据库测试，但我认为splitOn应该是您想要在下一个映射对象中的第一列，而不是前一个列中的最后一列。此外，列成为对象的成员，而不是整个值（尽管单列情况可能有例外情况，但我也没有方便的测试数据库）。

TL; DR - 尝试这样的事情

class ValuesObj{
    public string Values {get;set;}
}

// whatever code here

private Func<Position, ValuesObj, Position> GetPerson = new Func<Person, ValuesObj, Person>
((person, valuesObj) => {
                string values = valuesObj.Values;
                person.Values = Jil.JSON.Deserialize<Dictionary<string, string>>((string)values);
                return position;
            });

string sql =   "SELECT text
                FROM otherTable

                SELECT Name, Id, Age, Values 
                FROM People 
                WHERE Id = @Id"

SqlMapper.GridReader gridReader = connToDeviceConfig.QueryMultiple(sql, new {Id = 5}, commandType: CommandType.StoredProcedure);

List<string> listOfOtherStuff = gridReader.Read<string>().ToList();
List<Person> people = gridReader.Read<Person, ValuesObj, Person>(GetPerson, splitOn: "Values").ToList();

否则，我建议只使用dynamic返回Dapper方法。

如何在将一种类型映射到另一种类型时使用Dapper的多映射？

1 个答案: