Question

var query = (from material in dataContext.Materials
             join materialCategories in dataContext.MaterialCategories on material.Id equals
             materialCategories.Material.Id
             select new
                    {
                        material.Id,
                        material.Name,
                        material.Taken,
                        materialCategories.CategoryName
                    });
//Filter by date
query = query.Where(x => x.Taken >= minDate && x.Taken <= maxDate);

I want to extract the “query.Where(x => x.Taken >= minDate && x.Taken <= maxDate);” to a function that returns a query but the problem is that the function does not understand what x.Taken is.

How do i achieve this?

Answer 1

You need to use a named type instead of an unnamed one.
Make a new class:

public class Category
{
    int Id;
    string Name;
    DateTime Taken;
    string CategoryName;
}

You can make fields as properties if you want.

Then instead of:

select new {...}

use your class:

select new Category {...}

And after that you can have this:

private IQueryable<Category> FilterFunction(IQueryable<Category> query)
{
    query = query.Where(x => x.Taken >= minDate && x.Taken <= maxDate);
    return query;
}

Or use IEnumerable<> depending on what you are doing here exactly.