System.Linq.Dynamic.Core 无法将 'object' 类型转换为 'Tuple<T1, T2, T3>'

Question

我正在使用System.Linq.Dynamic.Core 并尝试使用以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", 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？

Answer 1

我不明白你为什么在 linq where 子句中写字符串。

以下是我的完整工作代码。

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：这对我有用。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();