groovy.transform

Annotation Type MapConstructor

@Documented
 @Retention(value=SOURCE)
 @Target(value=TYPE)
public @interface MapConstructor

Class annotation used to assist in the creation of map constructors in classes.

It allows you to write classes in this shortened form:

 import groovy.transform.*

 @TupleConstructor
 class Person {
     String first, last
 }

 @CompileStatic // optional
 @ToString(includeSuperProperties=true)
 @MapConstructor(pre={ super(args?.first, args?.last); args = args ?: [:] }, post = { first = first?.toUpperCase() })
 class Author extends Person {
     String bookName
 }

 assert new Author(first: 'Dierk', last: 'Koenig', bookName: 'ReGinA').toString() == 'Author(ReGinA, DIERK, Koenig)'
 assert new Author().toString() == 'Author(null, null, null)'
 

The @MapConstructor annotation instructs the compiler to execute an AST transformation which adds the necessary constructor method to your class.

A map constructor is created which sets properties, and optionally fields and super properties if the property/field name is a key within the map.

For the above example, the generated constructor will be something like:

 public Author(java.util.Map args) {
     super(args?.first, args?.last)
     args = args ? args : [:]
     if (args.containsKey('bookName')) {
         this.bookName = args['bookName']
     }
     first = first?.toUpperCase()
 }
 

Since:

2.5.0

Optional Element Summary

Optional Elements

Modifier and Type	Optional Element and Description
boolean	allNames Whether to include all fields and/or properties within the constructor, including those with names that are considered internal.
java.lang.String[]	excludes List of field and/or property names to exclude from the constructor.
boolean	includeFields Include fields in the constructor.
boolean	includeProperties Include properties in the constructor.
java.lang.String[]	includes List of field and/or property names to include within the constructor.
boolean	includeSuperProperties Include properties from super classes in the constructor.
java.lang.Class	post A Closure containing statements which will be appended to the end of the generated constructor.
java.lang.Class	pre A Closure containing statements which will be prepended to the generated constructor.
boolean	useSetters By default, properties are set directly using their respective field.

Element Detail

excludes

public abstract java.lang.String[] excludes

List of field and/or property names to exclude from the constructor. Must not be used if 'includes' is used. For convenience, a String with comma separated names can be used in addition to an array (using Groovy's literal list notation) of String values.

Default:

{}

includes

public abstract java.lang.String[] includes

List of field and/or property names to include within the constructor. Must not be used if 'excludes' is used. For convenience, a String with comma separated names can be used in addition to an array (using Groovy's literal list notation) of String values. The default value is a special marker value indicating that no includes are defined; all fields and/or properties are included if 'includes' remains undefined and 'excludes' is explicitly or implicitly an empty list.

Default:

"<DummyUndefinedMarkerString-DoNotUse>"

includeFields

public abstract boolean includeFields

Include fields in the constructor.

Default:

false

includeProperties

public abstract boolean includeProperties

Include properties in the constructor.

Default:

true

includeSuperProperties

public abstract boolean includeSuperProperties

Include properties from super classes in the constructor.

Default:

false

useSetters

public abstract boolean useSetters

By default, properties are set directly using their respective field. By setting useSetters=true then a writable property will be set using its setter. If turning on this flag we recommend that setters that might be called are made null-safe wrt the parameter.

Default:

false

pre

public abstract java.lang.Class pre

A Closure containing statements which will be prepended to the generated constructor. The first statement within the Closure may be "super(someArgs)" in which case the no-arg super constructor won't be called.

Default:

groovy.transform.Undefined.CLASS.class

post

public abstract java.lang.Class post

A Closure containing statements which will be appended to the end of the generated constructor. Useful for validation steps or tweaking the populated fields/properties.

Default:

groovy.transform.Undefined.CLASS.class

allNames

public abstract boolean allNames

Whether to include all fields and/or properties within the constructor, including those with names that are considered internal.

Default:

false