Querying the existence of data

[anggrayudi]

I am very often using this query to check if Realm contains specific data in a table. We could prevent code repetition using these two methods.

In many lines, I usually write the following code:

if (realm.where(Purchase.class).equalTo("sku", "pro").equalTo("purchased", true).exists()) {
    // activate paid items
}

[Zhuinden]

Hmm, I'm not an official Realm member, but I think while exists() can sound nice (although also easily possible to make into an extension function if you use Kotlin), the noData() name isn't that great for the other case.

I'd just prefer !realmQuery.exists().

[anggrayudi]

I forgot to mention that we need to optimize exists() performance by adding limit(1). So it will look like this:

public boolean exists() {
    return limit(1).count() > 0;
}

[cmelchior]

Given that exists() is just a shorthand for .count() > 0 or, as you point out .limit(1).count() > 0, then I'm not sure it is worth adding it to the API surface. It is just 1 extra method sure, but we also need to factor in the API surface of RealmQuery which is already rather large.