how do you split up or join a linq query on an "or" (without using Union)?

Question

Suppose you're searching some object with two boolean properties, A and B.

What if you have two linq queries:

IQueryable<ObjectType> query = getIQueryableSomehow()
query.Where(x => x.A);

IQueryable<ObjectType> query2 = getIQueryableSomehow()
query2.Where(x => x.B);

How can I join these queries together so that they are equivalent to this?:

IQueryable<ObjectType> query3 = getIQueryableSomehow()
query3.Where(x => x.A || x.B)

I would like to use query3 = query.Union(query2), but sadly in my Linq provider union is not supported.

I split up the case for x => x.A && x.B by chaining the where clause. This is what I mean:

IQueryable<ObjectType> query = getIQueryableSomehow();
query = query.Where(x => x.A);
query = query.Where(x => x.B);

Is there some similar workaround for the or case?

Thanks,

Isaac

Answer 1

using Predicate Builder

IQueryable<ObjectType> query = getIQueryableSomehow();
var predicate = PredicateBuilder.False<ObjectType>();
predicate = predicate.Or(x => x.A);
predicate = predicate.Or(x => x.B);

var list = query.Where(predicate).ToList();

Answer 2

If your LINQ provider doesn't support the Union operator, you can always first materialize the query results using ToArray(), and then use the LINQ-to-objects provider to perform the union, which it supports, like so:

IQueryable<ObjectType> query = getIQueryableSomehow() 
query.Where(x => x.A); 

IQueryable<ObjectType> query2 = getIQueryableSomehow() 
query2.Where(x => x.B); 

IQueryable<ObjectType> query3 = query.ToArray().AsQueryable<ObjectType>().Union(query2);

This will work well as long as your results being unioned are not too large.