IReferences

Interface to manage references stored in a map.

Description

The IReferences interface can be used to manage references stored in a map, and which can be passed to other components to establish dependencies between them.

Generally speaking, an IReferences object is a simple map, where keys are locators and values are component references. Thus, it allows you to add, remove and find components by their locators. Locators can be any values like integers, strings or component types.

Important points

  • Together with IReferenceable and IUnreferenceable interfaces, it implements a Locator pattern that is used by PipServices toolkit for Inversion of Control to assign external dependencies to components.
  • Generally, the PipServices toolkit uses Descriptor as locators that match according to the following fields: group, type, kind, name and version.

Instance methods

find

Gets all component references that match a specified locator.
Throws a ReferenceException when required is set to true but no references found.

List<T> find<T>(locator, bool required)

  • locator: dynamic - the locator to find a reference by.
  • required: bool - forces to raise an exception if no reference is found.
  • returns: List<T> - list with matching component references.

getAll

Gets all component references registered in this reference map.

List getAll()

  • returns: List - list with component references.

getAllLocators

Gets locators for all registered component references in this reference map.

List getAllLocators()

  • returns: List - list with component locators.

getOneOptional

Gets an optional component reference that matches specified locator.

T? getOneOptional<T>(locator)

  • locator: dynamic - locator to find references by.
  • returns: T? - matching component reference or null if nothing was found.

getOneRequired

Gets a required component reference that matches a specified locator.
Throws a ReferenceException when no references found.

T getOneRequired<T>(locator)

  • locator: dynamic - locator to find a reference by.
  • returns: T - matching component reference.

getOptional

Gets all component references that match a specified locator.

List<T> getOptional<T>(locator)

  • locator: dynamic - locator to find references by.
  • returns: List<T> - list with matching component references or empty list if nothing was found.

getRequired

Gets all component references that match a specified locator. At least one component reference must be present. If it doesn’t, the method throws an error.
Throws a ReferenceException when no references found.

List<T> getRequired<T>(locator)

  • locator: dynamic - locator to find references by.
  • returns: List<T> - list with matching component references.

put

Puts a new reference into this reference map.

void put(locator, component)

  • locator: dynamic - locator to find the reference by.
  • component: dynamic - component reference to be added.

remove

Removes a previously added reference that matches a specified locator. If many references match the locator, it removes only the first one. When all references shall be removed, use the removeAll method instead.

dynamic remove(locator)

  • locator: dynamic - locator to remove reference
  • returns: dynamic - removed component reference.

removeAll

Removes all component references that match the specified locator.

List removeAll(locator)

  • locator: dynamic - locator to remove references by.
  • returns: List - list, containing all removed references.

Examples

class MyController implements IReferenceable {
    IMyPersistence persistence;
    ...
    void setReferences(IReferences references) {
        persistence = references.getOneRequired<IMyPersistence>(
             Descriptor('mygroup', 'persistence', '*', '*', '1.0')
        );
    }
    ...
}
var persistence =  MyMongoDbPersistence();
var controller =  MyController();
var references = References.fromTuples([
     Descriptor('mygroup', 'persistence', 'mongodb', 'default', '1.0'), persistence,
     Descriptor('mygroup', 'controller', 'default', 'default', '1.0'), controller
]);
controller.setReferences(references);

See also