Hooks

trigger

before	after	methods	multi	details
yes	yes	create, patch, update, remove	yes	source

Options

The options of the trigger hook are of type: Subcription or Subcription[] or (context: HookContext) => Promisable<Subscription | Subscription[]>. But what is a Subcription?

A subscription is an object with the following properties:

Property	Description
service	The service to subscribe to. To be used if you share trigger options between several services/methods. Type: string | string[] optional - Default: undefined
method	The method to subscribe to. To be used if you share trigger options between several services/methods. Type: string | string[] optional - Default: undefined
conditionsData	Check the context.data for something. Uses sift.js under the hood. Replaces all {{ placeholders }} with the sub.view object. For more information, look at the View section down below. Type: Record<string, any> | boolean optional - Default: true
conditionsResult	Check the context.result for something. Uses sift.js under the hood. Replaces all {{ placeholders }} with the sub.view object. For more information, look at the View section down below. Type: Record<string, any> | boolean optional - Default: true
conditionsParams	Check the context.params for something. Uses sift.js under the hood. Replaces all {{ placeholders }} with the sub.view object. For more information, look at the View section down below. Type: Record<string, any> | boolean optional - Default: true
fetchBefore	The trigger hook lets you compare the result against the item before. This is disabled by default for performance reasons. If you use conditionsBefore, it will fetch the items in the before hook automatically. If you don't need conditionsBefore but your conditionsResult looks something like: { publishedAt: { $gt: '{{ before.publishedAt }}' } } you need to set fetchBefore:true explicitely Type: boolean optional - Default: false
conditionsBefore	Check the before object from trigger before hook, if available. Uses sift.js under the hood. Replaces all {{ placeholders }} with the sub.view object. For more information, look at the View section down below. Type: Record<string, any> | boolean optional - Default: true
view	The trigger function provides some view properties by default. See the View chapter down below. You can extend the view, if you need to. Type 1: Record<string, any> Type 2: (view, item, items, subscriptions, context) => Promisable<Record<string, any>> optional - Default: false
params	You can extend the params for the subscription, e.g. for population. Type: (params: Params, context: HookContext) => (Promisable<Params>) optional - Default: undefined
action	The action, that will be run, if all checks pass for the subscription. Type: ({ before, item }, { context, items, subscription, view }) => Promisable<any> Type (batchMode=true): (changes: [change: { before, item }, options: { context, items, subscription, view }][], context) => Promisable<any> optional - Default: undefined
batchMode	Enables batch mode. In batch mode: If multiple items are passed to create, it will only run action once with all items matching the conditions. Type: boolean optional - Default: false
isBlocking	Wether the trigger hook should wait for the async action before continuing. Type: boolean optional - Default: true
anything else	You can add whatever property you need for a subscription.

View

The concept of '' is heavily inspired by mustache.js where the render function takes a view object. That's why it's called view in feathers-trigger. Views can be used to transform conditionsData, conditionsBefore, conditionsResult and replace placeholder curly brackets strings with values. The trigger hook is capable of more complex conditions where you need to compare the result against data that is dynamic in the context.

Properties of views for mustache-like transformations of conditions have the following by default:

• item: the result item
• before: the item from the trigger before-hook
• data: context.data (see feathers.js docs)
• id: context.id (see feathers.js docs)
• method: context.method (see feathers.js docs)
• now: new Date() (see feathers.js docs)
• params: context.params (see feathers.js docs)
• path: context.path (see feathers.js docs)
• service: context.service (see feathers.js docs)
• type: context.type (see feathers.js docs)
• user: context.params.user (see feathers.js docs)

You can extend the views by the views option per subscription described above.

Action

The action from subscription is the function that runs, after all conditions are fulfilled. The function looks like the following:

const action = async (
  { before, item }, 
  { context, items, subscription, view }
) => {
  // do your own implementation
}

// In batch mode

const action = async (changes) => {
  for (const [{ before, item }, { context, items, subscription, view }] of changes) {
    // do your own implementation
  }
}

changesById

before	after	methods	multi	details
yes	yes	create, patch, update, remove	yes	source

Options

Property	Description
params	With the params options, you can manipulate params for changesById if you need to. Type: (params: Params, context: HookContext) => (Params | Promise<Params>) optional - Default: undefined
skipHooks	Use find or _find for refetching Type: boolean optional - Default: false