如何使用具有多个属性的集合过滤Dapper？

Question

我对Dapper有点新，并且正试图找到一种干净的方式将过滤器参数传递给具有多个属性的集合的SQL Query。

我的收藏是这样的：

[{ 
    Prop1: 'A Value 1', 
    Prop2: 'B Value 1' 
}, 
{ 
    Prop1: 'A Value 2', 
    Prop2: 'B Value 2' 
}] 

应导致SQL查询看起来像这样其中：

select * 
from SampleTable 
where 
([ColumnA]='A Value 1' and [ColumnB]='B Value 1') 
or ([ColumnA]='A Value 2' and [ColumnB]='B Value 2') 

注：事情是什么如下所示不会起作用，因为这两个属性PropA和PropB需要一起过滤。

string query = @"select * 
       from SampleTable 
       where [ColumnA] in (@PropA_Value) 
       and [ColumnB] in (@PropB_Value)" 

con.Query<T>(query, new{PropA_Value = PropA,PropB_Value = PropB}).AsList(); 

Answer 1

可以动态使用下面的辅助类生成过滤字符串：

public static class DapperHelper 
    { 
     private const string SingleTupleFormat = " [{0}] = '{1}' {2}"; 
     private const string AndString = "AND"; 
     private const string OrString = "OR"; 

     private static string ToSqlTuple(List<Dictionary<string, string>> filters) 
     { 
      string filterParam = string.Empty; 
      foreach (var filter in filters) 
      { 
       //Construct single tuple 
       string tuple = filter.ToList().Aggregate(string.Empty, 
       (current, pair) => current + String.Format(SingleTupleFormat, pair.Key, pair.Value, AndString)); 

       //Concatenate tuples by OR, string.Format to combine the different filters 
       filterParam += string.Format(" ({0}) {1}", tuple.TrimEnd(AndString), OrString); 
      } 
      return filterParam.TrimEnd(OrString); 
     } 

     public static string TrimEnd(this string source, string value) 
     { 
      if (!source.EndsWith(value)) 
       return source; 

      return source.Remove(source.LastIndexOf(value)); 
     } 
    } 

用法：

string query = @"select * 
       from SampleTable 
       where @where"; 

List<Dictionary<string, string>> filters = new List<Dictionary<string, string>>() { 
       new Dictionary<string, string>(){{"ColumnA", "A Value 1"},{"ColumnB", "A Value 2"}}, 
       new Dictionary<string, string>(){{"ColumnA", "B Value 1"},{"ColumnB", "B Value 2"}} 
      }; 

var tuple = DapperHelper.ToSqlTuple(filters); 
query = query.Replace("@where", string.IsNullOrEmpty(tuple) ? "1=1" : tuple); //Use 1=1 if tuple is empty or null 

var data = con.Query<T>(query).AsList(); 

查询字符串看起来像：

select * 
from SampleTable 
where ([ColumnA] = 'A Value 1' AND [ColumnB] = 'A Value 2') 
    OR ([ColumnA] = 'B Value 1' AND [ColumnB] = 'B Value 2')