LINQ lambda expression append OR statement

Question

If I want to append a AND statement to my query, I can do:

query = query.Where(obj=>obj.Id == id);

if(name.HasValue)
  query = query.Where(obj=>obj.Na         


        

Answer 1

I would use gdoron's solution, but if it seems unpractical for larger sets of queries, a slightly more complicated solution containing set operations might help you:

var queryById = query.Where(obj => obj.Id == id);
var queryByName = query.Where(obj => obj.Name == name);
query = queryById.Union(queryByName);

It gets much more difficult if your original query contains duplicate items.

Another way may be using Expression to formulate your queries. You can modify the expression tree before executing it, so you can add more conditions to the Where sub-tree. That is a whole lot of work and it's an overkill on 99.9% (rough estimate :) ) of cases.