System.Linq.Dynamic.Core不能将“object”类型强制转换为“Tuple<T1，T2，T3>”

Question

我正在使用System.Linq.Dynamic.Core并尝试使用一个模型运行一个动态查询，如下所示：

public class Index
{
    public long Position { get; set; }

    public object[] Values { get; set; }
}

下面是一个数据示例：

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", Tuple.Create<int, int>(3, 4) } });
indexes.Add(3, new Index { Position = 1002, Values = new object[3] { "Abby", "Yeremia", Tuple.Create<int, int>(5, 6)} });
indexes.Add(4, new Index { Position = 1003, Values = new object[3] { "Yonathan", "Gunawan", Tuple.Create<int, int>(7, 8)} });
indexes.Add(5, new Index { Position = 1004, Values = new object[3] { "Aldy", "Santoso", Tuple.Create<int, 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();

但是它总是抛出一个异常：

Exception: No property or field 'Tuple' exists in ...

在这里查询时不能使用type-casting吗？

Answer 1

我不明白为什么你要在linq where子句中写字符串。

下面是我那端完整的工作代码。

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", Tuple.Create<int, int>(3, 4) } });
            indexes.Add(3, new Index { Position = 1002, Values = new object[3] { "Abby", "Yeremia", Tuple.Create<int, int>(5, 6) } });
            indexes.Add(4, new Index { Position = 1003, Values = new object[3] { "Yonathan", "Gunawan", Tuple.Create<int, int>(7, 8) } });
            indexes.Add(5, new Index { Position = 1004, Values = new object[3] { "Aldy", "Santoso", Tuple.Create<int, 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:这对我很有效。不需要类型转换。

 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", Tuple.Create<int, int>(3, 4) } });
            indexes.Add(3, new Index { Position = 1002, Values = new object[3] { "Abby", "Yeremia", Tuple.Create<int, int>(5, 6) } });
            indexes.Add(4, new Index { Position = 1003, Values = new object[3] { "Yonathan", "Gunawan", Tuple.Create<int, int>(7, 8) } });
            indexes.Add(5, new Index { Position = 1004, Values = new object[3] { "Aldy", "Santoso", Tuple.Create<int, int>(11, 12) } });
            var queryable = indexes.Values.AsQueryable();
            var result = queryable.Where("Values[1].Equals(\"Yeremia\") || Values[2].Item2.Equals(8)").ToList();