exists( )

Refines a query to match items where the specified property contains a value.

The exists() function refines a PostsQueryBuilder to only match items where the value of the specified propertyName doesn't equal null or undefined. exists() checks for either existence or non-existence based on the boolen parameter. Note that exists() does match items where the value of the specified propertyName is an empty string or an invalid value. exists() is only useful for properties which don't contain default values and therefore their values may be unassigned.