add immutability-helper

package.json

@@ -4,6 +4,7 @@
   "description": "A redux reducer for standard action that merge data to state",
   "main": "lib/index.js",
   "dependencies": {
+    "immutability-helper": "^2.3.1",
     "lodash.mergewith": "^4.6.0"
   },
   "devDependencies": {

src/index.js

@@ -1,4 +1,9 @@
+import assert from 'assert'
 import _mergeWith from 'lodash.mergewith'
+import update from 'immutability-helper'
+
+// export `update`
+export { update }
 
 // lodash, mergeWith
 export const customMerger = (cur, newValue) => {
@@ -38,12 +43,25 @@ export function mergeState(...args) {
  */
 
 export default function standardReducer(state, action) {
-  if (!action || !action.type || !action.payload) return state
+  if (!action || !action.type) return state
 
   // STANDARD_MERGE_STATE
   const ok =
     action.type.startsWith('STANDARD_MERGE_STATE') || Boolean(action.standard)
   if (!ok) return state
 
-  return mergeState(state, action.payload)
+  // use immutability-helper `update`
+  if (action.update) {
+    if (typeof action.update !== 'object') {
+      throw new Error('expect standard action.update = object')
+    }
+    state = update(state, action.update)
+  }
+
+  // merge
+  if (action.payload) {
+    state = mergeState(state, action.payload)
+  }
+
+  return state
 }

test/mergeState.js

@@ -1,5 +1,5 @@
-import { mergeState } from '../src/index'
 import assert from 'assert'
+import { mergeState } from '../src/index'
 
 describe('mergeState', function() {
   it('nothing to merge', function() {

test/update.js

@@ -0,0 +1,70 @@
+import assert from 'assert'
+import reduceReducers from 'reduce-reducers'
+import { combineReducers } from 'redux'
+import standardReducer from '../src/index'
+
+/* eslint no-extra-semi: off */
+
+describe('immutability-helper', function() {
+  let reducer
+  let state
+
+  beforeEach(() => {
+    reducer = reduceReducers(
+      standardReducer,
+      (state = { arr: [] }, action) => state,
+      combineReducers({
+        partial1(state = { value: 1, foo: 'bar-1' }, action) {
+          return state
+        },
+
+        partial2(state = { value: 2, foo: 'bar-2' }, action) {
+          return state
+        },
+      })
+    )
+
+    // init
+    state = {}
+    state = reducer(state, { type: 'init' })
+    state.partial1.value.should.equal(1)
+    state.partial2.value.should.equal(2)
+  })
+
+  it('it works', function() {
+    state = reducer(state, {
+      type: 'UPDATE_PARTIAL_1',
+      standard: true,
+      update: {
+        partial1: {
+          foo: { $set: 'updated-foo-1' },
+        },
+      },
+    })
+    state.partial1.foo.should.equal('updated-foo-1')
+
+    // init `partial1.sub` to object
+    state = reducer(state, {
+      type: 'UPDATE_PARTIAL_1',
+      standard: true,
+      update: {
+        partial1: {
+          sub: {
+            $apply: sub => sub || {},
+          },
+        },
+      },
+    })
+    assert(state.partial1.sub)
+  })
+
+  it('throws when `action.update` not object', function() {
+    ;(() => {
+      state = reducer(state, {
+        type: 'SOME_ACTION_TYPE',
+        standard: true,
+        update: 1,
+      })
+    }).should.throw(/expect standard action.update = object/)
+  })
+})