CODEWITHSUNDEEP
entity-frameworklinq-to-entitiesiqueryable
Elisabeth
Elisabeth

Reputation: 21206

Build an IQueryable from multiple predicates

I want to build a query with where condition for filter properties when they have a value (not null). The multiple filters must be a AND combination if they are used.

How can combine/add each predicate when the according property value is not null to get a final query ready for filtering?

IQueryable<Customer> filter = null;

Expression<Func<Customer, bool>> predicatetest1 = res => res.test1 == request.test1;
Expression<Func<Customer, bool>> predicatetest2 = res => res.test2 == request.test2;
Expression<Func<Customer, bool>> predicatetest3 = res => res.test3 == request.test3;

if (request.test1 != null)
{
     // add the above predicate to the filter
}

if (request.test2 != null)
{
    // add the above predicate to the filter
}

if (request.test3 != null)
{
   // add the above predicate to the filter
}

Upvotes: 2

Views: 1390

Answers (1)

Jehof
Jehof

Reputation: 35544

IQueryable<Customer> filter = Context.Customers;

if (request.test1 != null)
{
  filter = filter.Where(predicatetest1);
}

if (request.test2 != null)
{
  filter = filter.Where(predicatetest2);
}

if (request.test3 != null)
{
  filter = filter.Where(predicatetest3);
}

var customers = filter.ToList();

The following would be equivalent, when all 3 properties where not null

Context.Customers.Where(predicatetest1).Where(predicatetest2).Where(predicatetest3).ToList();

Upvotes: 2

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