问题描述
我正在使用 System.Linq.Dynamic.Core 并尝试使用如下模型运行动态查询:
public class Index
{
public long Position { get; set; }
public object[] Values { get; set; }
}
还有这样的数据样本:
var indexes = new Dictionary<long,Index>();
indexes.Add(1,new Index { Position = 1000,Values = new object[3] { "Welly","Chandra",Tuple.Create<int,int>(1,2) } });
indexes.Add(2,new Index { Position = 1001,Values = new object[3] { "Darma","Angelo",int>(3,4) } });
indexes.Add(3,new Index { Position = 1002,Values = new object[3] { "Abby","Yeremia",int>(5,6)} });
indexes.Add(4,new Index { Position = 1003,Values = new object[3] { "Yonathan","Gunawan",int>(7,8)} });
indexes.Add(5,new Index { Position = 1004,Values = new object[3] { "Aldy","Santoso",int>(11,12)} });
var queryable = indexes.Values.AsQueryable();
var result = queryable.Where("Values[1].Equals(\"Yeremia\") || ((Tuple<int,int>) Values[2]).Item2.Equals(8)").ToList();
但它总是抛出异常:
Exception: No property or field 'Tuple' exists in ...
这里查询时不能使用type-casting
吗?
解决方法
我不明白你为什么在 linq where 子句中写字符串。
以下是我最后的完整代码。
var indexes = new Dictionary<long,Index>();
indexes.Add(1,new Index { Position = 1000,Values = new object[3] { "Welly","Chandra",Tuple.Create<int,int>(1,2) } });
indexes.Add(2,new Index { Position = 1001,Values = new object[3] { "Darma","Angelo",int>(3,4) } });
indexes.Add(3,new Index { Position = 1002,Values = new object[3] { "Abby","Yeremia",int>(5,6) } });
indexes.Add(4,new Index { Position = 1003,Values = new object[3] { "Yonathan","Gunawan",int>(7,8) } });
indexes.Add(5,new Index { Position = 1004,Values = new object[3] { "Aldy","Santoso",int>(11,12) } });
var queryable = indexes.Values.AsQueryable();
var result = queryable.Where(cc=>cc.Values[1].Equals("Yeremia") || ((Tuple<int,int>) cc.Values[2]).Item2.Equals(8)).ToList();
更新:这对我有用。不需要类型转换。
var indexes = new Dictionary<long,12) } });
var queryable = indexes.Values.AsQueryable();
var result = queryable.Where("Values[1].Equals(\"Yeremia\") || Values[2].Item2.Equals(8)").ToList();