Need to solve C# Error u003Ef__AnonymousType0

Question

I have a c# code as below, Its showing error at IEnumerable<\u003C\u003Ef__AnonymousType0 Can someone tell me how to solve it.

dataSet = this.GetData.getInfo("SELECT b.nBatchID, td.F_Name &' '& td.M_Name &' '& td.L_Name AS StaffName, b.BatchName FROM (Batch AS b LEFT JOIN BatchTrainer AS bt ON b.nBatchID = bt.nBatchId) LEFT JOIN TrainerDetails AS td ON bt.TrainerId = td.TrainerID", "Batch");
            IEnumerable<\u003C\u003Ef__AnonymousType0<object, string, string>> datas = dataSet.Tables[0].Copy().AsEnumerable().GroupBy<DataRow, object>((Func<DataRow, object>) (row => row["nBatchId"])).Select(g =>
            {
              var data = new{ id = g.Key, text = string.Join(",", g.Select<DataRow, string>((Func<DataRow, string>) (r => r["StaffName"].ToString())).ToArray<string>()), Batch = g.Select<DataRow, string>((Func<DataRow, string>) (r => r["BatchName"].ToString())).FirstOrDefault<string>() };
              return data;
            });
            table.Columns.Add("nBatchId", typeof (int));
            table.Columns.Add("StaffName", typeof (string));
            table.Columns.Add("BatchName", typeof (string));
            foreach (var data in datas)
              table.Rows.Add(data.id, (object) data.text, (object) data.Batch);
            dataSet.Tables.Clear();
            dataSet.Tables.Add(table);

Don't copy-paste code out of decompilers. They do not necessarily generate correct code. — Eric Lippert, Apr 11 '17 at 15:58

score 6 · Accepted Answer · edited Sep 04 '19 at 08:35

Don't specify type name when you deal with anonymous types. Use var instead to make compiler infer type for you:

var datas = dataSet.Tables[0].Copy().AsEnumerable()
             .GroupBy(row => row.Field<int>("nBatchId"))
             .Select(g => new { 
                 id = g.Key, 
                 text = string.Join(",", g.Select(r => r.Field<string>("StaffName")),
                 Batch = g.Select(r => r.Field<string>("BatchName")).FirstOrDefault()
             });

Other considerations:

Don't specify generic parameters for LINQ extension methods. Compiler will infer generic parameters from type of source sequence
Don't specify type of predicate for LINQ extension methods. Same as above, compiler will infer type from source sequence
Use Field<T>("columnName") extension for DataRow to get nicely typed cell values
Don't create copy of DataTable just for querying it. LINQ will not modify original DataTable
Don't put values which you are passing to String.Join method into array. There is method overload which accepts IEnumerable<T>

Thanks man you solved my big problem.. basically i got this code from some where.. — Amaan Khan, Apr 11 '17 at 15:48

Need to solve C# Error u003Ef__AnonymousType0

1 Answers1