Building Query in for loop

[Kometa]

Hey,

I wanted to use query with a different number of parameters according to the input from the user.

That's what I have done:

 

Collection<Query> queries = new ArrayList<Query>();
for(int num : numbers){
    queries.add(equal(MyNewResultSet.FEATURES, num));
}

Query query2 = and(queries);

but it does say that the argument in the "and" is incorrect. Is there a way to build a list of arguments for "and"?

Thanks

[Niall Gallagher]

Hi Kometa,

You need at least two child queries for and(). And in case you have no features to query, you need to decide then if the resulting query should match no objects, or all items.

You can write a helper method like this:

static Query<Car> queryFeatures(Collection<Query<Car>> features) {
    switch (features.size()) {
        case 0: return none(Car.class); // or all(Car.class) -- depends on your application needs
        case 1: return features.iterator().next();
        default: return and(features);
    }
}

Hope that helps,

Niall

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[Kometa]

Hello Niall,

Yes you did help me! It was not the issue that there was only one argument. The problem was in the queries variable type.

I set it to :

Collection<Query> queries = new ArrayList<Query>();

Should be:

Collection<Query<MyNewResultSet>> queries = new ArrayList<Query<MyNewResultSet>>();

but thanks for a hint!

Kometa

[Niall Gallagher]

No problem, glad it's working :)