feat: Model classes emit Feathers service events

Model classes are now EventEmitter instances which emit service events when received.  All FeathersJS events are supported.  Here’s an example of how to use it in a component:

```js
export default {
   created() {
      this.$FeathersVuex.api.Todo.on(‘created’, this.handleTodoCreated)
   },
   methods: {
      handleTodoCreated(todo) {
         console.log(todo)
      }
   }
}
```

Author: marshallswain

package.json

@@ -107,6 +107,7 @@
     "@types/npm": "^2.0.31",
     "bson-objectid": "^1.3.0",
     "debug": "^4.1.1",
+    "events": "^3.0.0",
     "fast-copy": "^2.0.4",
     "fast-json-stable-stringify": "^2.0.0",
     "inflection": "^1.12.0",

src/service-module/make-model.ts

@@ -8,6 +8,7 @@ import { globalModels, prepareAddModel } from './global-models'
 import { mergeWithAccessors, checkNamespace, getId } from '../utils'
 import _merge from 'lodash/merge'
 import _get from 'lodash/get'
+import EventEmitter from 'events'
 
 // A hack to prevent error with this.constructor.preferUpdate
 interface Function {
@@ -385,6 +386,10 @@ export default function makeModel(options: FeathersVuexOptions) {
       return _merge({}, this)
     }
   }
+  for (var n in EventEmitter.prototype) {
+    BaseModel[n] = EventEmitter.prototype[n]
+  }
+
   addModel(BaseModel)
   return BaseModel
 }

src/service-module/make-service-plugin.ts

@@ -92,18 +92,30 @@ export default function prepareMakeServicePlugin(
       // (3^) Setup real-time events
       if (options.enableEvents) {
         // Listen to socket events when available.
-        service.on('created', item =>
+        service.on('created', item => {
           store.dispatch(`${options.namespace}/addOrUpdate`, item)
-        )
-        service.on('updated', item =>
+          if (Model.emit) {
+            Model.emit('created', item)
+          }
+        })
+        service.on('updated', item => {
           store.dispatch(`${options.namespace}/addOrUpdate`, item)
-        )
-        service.on('patched', item =>
+          if (Model.emit) {
+            Model.emit('updated', item)
+          }
+        })
+        service.on('patched', item => {
           store.dispatch(`${options.namespace}/addOrUpdate`, item)
-        )
-        service.on('removed', item =>
+          if (Model.emit) {
+            Model.emit('patched', item)
+          }
+        })
+        service.on('removed', item => {
           store.commit(`${options.namespace}/removeItem`, item)
-        )
+          if (Model.emit) {
+            Model.emit('removed', item)
+          }
+        })
       }
     }
   }

test/service-module/model-base.test.ts

@@ -84,6 +84,22 @@ describe('makeModel / BaseModel', function () {
         `has ${method} method`
       )
     })
+
+    const eventMethods = [
+      'on',
+      'off',
+      'once',
+      'emit',
+      'addListener',
+      'removeListener',
+      'removeAllListeners'
+    ]
+    eventMethods.forEach(method => {
+      assert(
+        typeof BaseModel[method] === 'function',
+        `has ${method} method`
+      )
+    })
   })
 
   it('allows customization through the FeathersVuexOptions', function () {

test/service-module/model-methods.test.ts

@@ -165,6 +165,21 @@ describe('Models - Methods', function () {
     assert(typeof Task.getFromStore === 'function')
   })
 
+  it('allows listening to Feathers events on Model', function (done) {
+    const { Letter } = makeContext()
+
+    Letter.on('created', data => {
+      assert(data.to === 'Santa', 'received event with data')
+      done()
+    })
+
+    // This should trigger an event from the bottom of make-service-plugin.ts
+    const letter = new Letter({
+      from: 'Me',
+      to: 'Santa'
+    }).save()
+  })
+
   it('instance.save calls create with correct arguments', function () {
     const { Task } = makeContext()
     const task = new Task({ test: true })