此表达式会产生副作用，不进行评估

Question

我在LINQ查询上得到这个错误，我不确定为什么。当我运行表是空的，但当我添加一个断点，一个力的结果，然后它的工作找到并添加所有的数据在完美

    private void GetSQLOraclelinqData()
    {
        var TstarData = GetTrackstarTruckData();
        var M5Data = GetM5Data();
        DataTable ComTable = new DataTable();
        foreach (DataColumn OraColumn in M5Data.Columns)
        {
            ComTable.Columns.Add(OraColumn.ColumnName, OraColumn.DataType); 
        }
        foreach (DataColumn SQLColumn in TstarData.Columns)
        {
            if (SQLColumn.ColumnName == "VehicleName")
                ComTable.Columns.Add(SQLColumn.ColumnName + 2, SQLColumn.DataType);
            else
                ComTable.Columns.Add(SQLColumn.ColumnName, SQLColumn.DataType);
        }
        var results = TstarData.AsEnumerable().Join(M5Data.AsEnumerable(),
            a => a.Field<String>("VehicleName"),
            b => b.Field<String>("Unit_NO"),
                (a, b) =>
                {
                    DataRow row = ComTable.NewRow();
                    row.ItemArray = a.ItemArray.Concat(b.ItemArray).ToArray();
                    ComTable.Rows.Add(row);
                    return row;
                });
        SQLDataTable.ItemsSource = ComTable.DefaultView;
    }

Answer 1

添加列表:

var results = TstarData.AsEnumerable().Join(M5Data.AsEnumerable(),
            a => a.Field<String>("VehicleName"),
            b => b.Field<String>("Unit_NO"),
                (a, b) =>
                {
                    DataRow row = ComTable.NewRow();
                    row.ItemArray = a.ItemArray.Concat(b.ItemArray).ToArray();
                    ComTable.Rows.Add(row);
                    return row;
                }).ToList();