Linq - SQL passing parameters into GroupBy()

Question

Using a linq query, how can i pass parameters into the groupby function? Depend on user selection, it will be grouped differently

 var query = (from to in OrderQuery
                     group to by to.FromDateUtc into groupedDate
                     let grouped = groupedDate.GroupBy(o => o.Name)

I would like to pass different groupby values. Any idea?

Cheers

Answer 1

Generally speaking, you need different queries for this. The same goes for building up different WHERE or Where(...) clauses based on user selection:

var query = OrderQuery;
if (userSelection == "GroupByName") {
    query = from to in query
            group to by to.FromDateUtc into groupedDate
            let grouped = groupedDate.GroupBy(o => o.Name);
}
else if (userSelection == "GroupBySomethingElse") {
    query = from to in query
            group to by to.FromDateUtc into groupedDate
            let grouped = groupedDate.GroupBy(o => o.SomethingElse);
}

You'll want to prepare as much common logic as possible before you apply the grouping to query . Because LINQ uses deferred execution you can modify query as much as you need before enumerating the result and you will not incur a performance hit.

Answer 2

If you are trying to do something like this

SELECT * FROM <TableName> GROUP BY <Column1>,<Column2>

Then, take a look at this post

Group By Multiple Columns