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This section provides query methods that you can use to retrieve an array of elements by query pattern.
Retrieving an Array of Element by Query Pattern
$query.get(query)
- Parameters: query : String (the query string as described in section Recognizable Query Patterns.
- Returns: java.util.List<Element> (a list or a collection of elements or an empty List if there is no matching element).
- The sample code to print all Use Case elements under a packagable element named foo is as follows:
#foreach ($uc in $query.get("usecase[owner=foo]"))
$uc.name in $uc.owner.name
#end
Getting a Single Result from Query Functions
Since a model element does not have a unique identified attribute so all methods will be returned in a Collection. Thus we will need convenient methods to get a single result from the Collection. Additional methods for getting a single result from query methods are as follows:
- first() – returns the first element from a collection.
- last() – returns the last element from a collection.
- get(int) – returns the nth element of a collection.
- unique() – returns the first element from a collection (equivalent to first).
Getting the First Element from a Collection
$query.get(query).first()
- Returns: Element (the first element from a query result collection or a null value if there is no matching element).
- A Sample code to print the first package is as follows:
$query.get("package").first()
Getting the Last Element from a Collection
$query.get(query).last()
- Returns: Element (the last element from a query result collection or a null value if there is no matching element).
- A sample code to print the last package is as follows:
$query.get("package").last()
Getting the nth Element from a Collection
$query.get(query).get(index)
- Parameters: index : int (a zero-based integer indicating which element to retrieve).
- Returns: Element (an element from a specified index of a query result collection or if the index is out of bounds, it will print a warning message to console/log and returns a null value)
- A sample code to print the third package is as follows:
$query.get("package").get(2)
Getting the Unique Element from a Collection
$query.get(query).unique()
This method is equivalent to the one in section Getting the First Element from a Collection.
- Returns: Element (a unique element from a query result collection or a null value if there is no matching element).
- A sample code to print a single package is as follows:
$query.get("package").unique()
Retrieving an Array of Elements by Name
$query.getElementsByName(name)
Retrieve an element from a selected package scope whose element name exactly equals a given parameter. This method is equivalent to query pattern *[name=var].
- Parameters: name : String (the element name string).
- Returns: java.util.List<Element> (a List or a collection of elements or an empty List if there is no matching element).
- A sample code to print the first element whose name exactly equals to foo is as follows:
$query.getElementsByName("foo").unique()
Retrieving Elements by ID
$query.getElementById(id)
Retrieve an element from a selected package scope whose element ID exactly equals a given parameter. This method is equivalent to query pattern #id.
- Parameters: id : String (an element’s ID).
- Returns: Element (an element or a null value if there is no matching element).
- A sample code to print an element that contains ID 17_0_3_8e9027a_1325220298609_477646 is as follows:
$query.getElementById("17_0_3_8e9027a_1325220298609_477646")