How to refer to a field in a dynamic linq query?
I have a query that needs to be dynamic, I think most of my syntax is right but I开发者_C百科 do not know how to give it the name of the column I want to group by. I have tried a few different approaches and I always get an error - "No property or field 'name' exists in type 'datarow'
IQueryable<Result> aggregate1 =
query1Data.Tables[0].AsEnumerable().AsQueryable()
.GroupBy("name", "it")
.Select<Result>("new(Key as Group, Sum(value)as Total)");
I assume I have to use something like Field<string>("name")
but I cant figure it out. I have seen the problem on a few forums but no one seems to have a clear answer how to get around the problem.
Is this what you were trying to do?
var aggregate1 =
query1Data.Tables[0].AsEnumerable().AsQueryable()
.GroupBy(row => row.Field<string>("name"), row => row.Field<int>("it"))
.Select(g => new { Group = g.Key, Total = g.Sum() });
I'm not sure I understand exactly what you want, but here is a little snippet of code you may use as inspiration:
var dataTable = new DataTable();
dataTable.Columns.Add("Name", typeof(String));
dataTable.Columns.Add("Value", typeof(Int32));
dataTable.Rows.Add("A", 1);
dataTable.Rows.Add("A", 2);
dataTable.Rows.Add("B", 3);
dataTable.Rows.Add("B", 4);
var aggregate = dataTable.AsEnumerable()
.GroupBy(row => row.Field<String>("Name"), row => dataRow.Field<Int32>("Value"))
.Select(group => new { Name = group.Key, Total = group.Sum() });
foreach (var row in aggregate)
Console.WriteLine(row.Name + " = " + row.Total);
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