Multiple where conditions in EF [duplicate]

Answer 1

Assuming that Location and Category are identified in your code by ids (id is the value attribute in the comboboxes items), you can do something similar to

function GetItems(string keyword, string consultant, int? locationId, int categoryId){

using(MyContextEntities context = new MyContextEntities()){
    return context.Items.Where(item => 
        (string.IsNullOrEmpty(keyword) || item.Text.Contains(keyword))
        && (string.IsNullOrEmpty(consultant) || item.Consultant.Contains(consultant))
        && (!locationId.HasValue || item.Location.Id == locationId.Value)
        && (!categoryId.HasValue || item.Category.Id == categoryId.Value)
    );
}
}