All repositories have the ability to execute queries. A query is a request to find all of the items of a particular item type that fits a certain set of criteria. Those criteria are specified in terms of the item type’s properties. For example:
Find all Person items whose age property is greater than 30
The Repository API can express a wide variety of queries, including queries that match patterns in text, query through collections, or even query through complex values. Queries can also specify the order in which results should be returned, and can specify which results from a large result set should be returned. For example, a query can express something like:
Find all Person items whose
lastNamestarts with ‘A’,
whose interests includes ‘biking’, and
whose addresses property contains an Address with azipCodeof ‘02139’.
Order the results bylastName, and return only items 10-20.
Queries can be built and executed using the Repository API. For complex queries, this can be a tedious task. In these cases, or in cases where the Repository API should not be used directly, queries can be represented in a textual form called Repository Query Language (RQL). See the Repository Query Language section of this chapter for details of this language and other information about repository queries. In most cases, however, repository queries can be constructed easily using targeting UI components in the ATG Control Center.
