resources

This module provides helpers for patterns regarding didReplace and didUpdate events.

Contents

Module Members

• replacePublisherForFeature()
• updatePublisherForFeature()
• handlerFor()

Types

• ResourceHandler
  • ResourceHandler.registerResourceFromFeature()
  • ResourceHandler.registerResource()
  • ResourceHandler.whenAllWereReplaced()
  • ResourceHandler.wereAllReplaced()

Module Members

replacePublisherForFeature( context, featurePath, optionalOptions )

Creates and returns a function to publish didReplace events for the resource found as feature configuration. Resolution of the featurePath argument works just as explained in the documentation for #ResourceHandler.registerResourceFromFeature. The publisher returns the promise returned by the underlying event bus call.

Parameters

Returns

updatePublisherForFeature( context, featurePath, optionalOptions )

Creates and returns a function to publish didUpdate events for the resource found as feature configuration. Resolution of the featurePath argument works just as explained in the documentation for #ResourceHandler.registerResourceFromFeature. The publisher returns the promise returned by the underlying event bus call. The returned function only accepts one argument, which is the JSON patch sequence conforming to RFC 6902.

Example:

const publisher = resources.updatePublisherForFeature( context, path );
publisher( [
   { op: 'remove', path: '/accounts/2' },
   { op: 'replace', path: '/contacts/hans/number', value: '+49 123 4563432' }
] );

Additionally the returned function has a method compareAndPublish that accepts the previous version of a resource as first argument and the current version of the resource as second argument. It then creates the JSON patch sequence itself and sends the according didUpdate event. It also returns the promise returned by the underlying event bus call.

Example:

const publisher = resources.updatePublisherForFeature( context, path );
publisher.compareAndPublish( obsoleteVersion, currentVersion );

Note that a generic generation of patches might lead to strange, large patch sequences, especially when removing entries. The diff library doesn't know about identities and as such won't recognize where a specific element was removed. As a consequence instead of generating a remove operation, this could result in a very large number of replace operations that shift the properties from successors to the front in order to overwrite instead of remove the entry. In such cases one is better off by manually creating a patch with operation remove, as the knowledge about the domain is available at the user of this publisher.

Parameters

Returns

handlerFor( context )

Creates a new handler instance for didReplace and didUpdate events. It already handles setting of the resource data on didReplace in the context.resources property and updating that data on didUpdate events.

Parameters

Returns

Types

ResourceHandler

ResourceHandler.registerResourceFromFeature( featurePath, optionalOptions )

Registers default event handlers for a feature. The feature argument is interpreted as attribute path to an object having a resource property of type string holding the name of the resource to register the handler for. All replacements and updates will be written to context.resources according to the rules found at the optionalOptions.modelKey doc.

Example: Consider the following configuration:

{
   "features": {
      "someFeature": {
         "someResourceConfig": {
            "resource": "myResource"
         }
      }
   }
}

The corresponding call would be (providing none of the options):

resources.handlerFor( context )
   .registerResourceFromFeature( 'someFeature.someResourceConfig' );

Parameters

Returns

ResourceHandler.registerResource( resource, optionalOptions )

Registers default event handlers for a known resource name.All replacements and updates will be written to context.resources according to the rules found at the optionalOptions.modelKey doc.

Parameters

Returns

ResourceHandler.whenAllWereReplaced( callback, optionalOptions )

Registers a callback that is called once all registered resources were initially replaced. If more resource handlers are registered before all relevant didReplace events were received, those are also waited for.

Parameters

Returns

ResourceHandler.wereAllReplaced()

Allows to find out if there are still outstanding resources, or if all resources have been replaced. Can be used in update-/replace-handlers to determine if all dependencies are satisfied.

Returns