JDO querys with OR in GAE

Question

Got an entity A with like this

public class A
 private String a;
 private String b;
..
..
..

How do I write a JDO query that select all the A objects that matches either keyword==a OR keyword ==b

Full code looks something like this:

Query q = pm.newQuery(SELECT FROM A WHERE a == keyword || b == keyword ORDER BY date DESC");

        List<A> results = (List<A>)q.execute(keyword);

This code does not give any error but does not give any results. Removing the || part gives results.

Thanks

Answer 1

You can't do an OR on two different fields. Here is a snippet from the docs:

In the JDOQL string syntax, you can separate multiple filters with || (logical "or") and && (logical "and"), although keep in mind that || can only be employed when the filters it separates all have the same field name. In other words, || is only legal in situations where the filters it separates can be combined into a single contains() filter:

// legal, all filters separated by || are on the same field
Query query = pm.newQuery(Employee.class,
                          "(lastName == 'Smith' || lastName == 'Jones')" +
                          " && firstName == 'Harold'");

// not legal, filters separated by || are on different fields
Query query = pm.newQuery(Employee.class,
                          "lastName == 'Smith' || firstName == 'Harold'");

One way around this might be to store your a and b in a list. If you have a list of items called foo, you could do a query where foo = keyword, and if any item in foo matches, you will get that object back in your results. You don't say much about what a and b are, so I don't know if this will work for you or not :)

Update:

public class Example {
    String firstName;
    String lastName;
    List<String> allNames;

    public Example(String first, String last){
        firstName = first;
        lastName = last;
        allNames = new ArrayList<String>();
        allNames.add(first);
        allNames.add(last);
    }
 }

With something like that, you could then do a query where "allNames == 'Smith' || allNames=='Jones'".