# Usage

As a standard plugin for Vuex, undo-redo-vuex can be used with the following setup:

# How to use it in your store module

The scaffoldStore helper function will bootstrap a vuex store to setup the state, actions and mutations to work with the plugin.

import { scaffoldStore } from "undo-redo-vuex";

const state = {
  list: [],
  /**
   * 'resetList' is a placeholder (initially the same as 'list') to 
   * fast-forward 'list' during a 'reset()'
   */
  resetList: [],
  // Define vuex state properties as normal
};
const actions = {
  // Define vuex actions as normal
};
const mutations = {
  /*
   * NB: The emptyState mutation HAS to be implemented.
   * This mutation resets the state props to a "base" state,
   * on top of which subsequent mutations are "replayed"
   * whenever undo/redo is dispatched.
   */
  emptyState: state => {
    // Sets some state prop to the 'reset placeholder' value
    state.list = [...state.resetList];
  },

  resetState: state => {
    // Sets the 'reset placeholder' (see state.resetList) prop to the current state
    state.resetList = [...state.list];
  },

  // Define vuex mutations as normal
};

export default scaffoldStore({
  state,
  actions,
  mutations,
  namespaced: true, // NB: do not include this is non-namespaced stores
});

# Setting up `emptyState` and `resetState` mutations

The undo and redo functionality requires the emptyState mutation (in the example above) to be defined by the developer. This mutation (which is not tracked in the undo and redo stacks) allows state to be 'replayed' in the chronological order mutations are executed. The clear() action also commits emptyState to re-initialize the store to its original state. The reset() action additionally requires the resetState mutation to be defined, allowing the state to 'fast-forward' to its point when reset() was called before other mutations are 'replayed'.

Alternatively, the scaffoldState, scaffoldActions, and scaffoldMutations helper functions can be individually required to bootstrap the vuex store. This will expose canUndo and canRedo as vuex state properties which can be used to enable/disable UI controls (e.g. undo/redo buttons).

import {
  scaffoldState,
  scaffoldActions,
  scaffoldMutations,
} from "undo-redo-vuex";

const state = {
  list: [],
  resetList: [],
  // Define vuex state properties as normal
};
const actions = {
  // Define vuex actions as normal
};
const mutations = {
  emptyState: state => {
    state.list = [...(state.resetList || [])];
  },
  resetState: state => {
    // Sets the 'reset placeholder' (see state.resetList) prop to the current state
    state.resetList = [...state.list];
  },
  // Define vuex mutations as normal
};

export default {
  // Use the respective helper function to scaffold state, actions and mutations
  state: scaffoldState(state),
  actions: scaffoldActions(actions),
  mutations: scaffoldMutations(mutations),
  namespaced: true, // NB: do not include this is non-namespaced stores
};

# Setup the store plugin

Namespaced modules

import Vuex from "vuex";
import undoRedo from "undo-redo-vuex";

// NB: The following config is used for namespaced store modules.
// Please see below for configuring a non-namespaced (basic) vuex store
export default new Vuex.Store({
  plugins: [
    undoRedo({
      // The config object for each store module is defined in the 'paths' array
      paths: [
        {
          namespace: "list",
          // Any mutations that you want the undo/redo mechanism to ignore
          ignoreMutations: ["addShadow", "removeShadow"],
        },
      ],
    }),
  ],
  /*
   * For non-namespaced stores:
   * state,
   * actions,
   * mutations,
   */
  // Modules for namespaced stores:
  modules: {
    list,
  },
});

Non-namespaced (basic) vuex store

import Vuex from "vuex";
import undoRedo from "undo-redo-vuex";

export default new Vuex.Store({
  state,
  getters,
  actions,
  mutations,
  plugins: [
    undoRedo({
      // NB: Include 'ignoreMutations' at root level, and do not provide the list of 'paths'.
      ignoreMutations: ["addShadow", "removeShadow"],
    }),
  ],
});

# Accessing `canUndo` and `canRedo` properties

Vue SFC (.vue)

import { mapState } from "vuex";

const MyComponent = {
  computed: {
    ...mapState({
      undoButtonEnabled: "canUndo",
      redoButtonEnabled: "canRedo",
    }),
  },
};

# Undoing actions with `actionGroups`

In certain scenarios, undo/redo is required on store actions which may consist of one or more mutations. This feature is accessible by including a actionGroup property in the payload object of the associated vuex action. Please refer to test/test-action-group-undo.js for more comprehensive scenarios.

vuex module

const actions = {
  myAction({ commit }, payload) {
    // An arbitrary label to identify the group of mutations to undo/redo
    const actionGroup = "myAction";

    // All mutation payloads should contain the actionGroup property
    commit("mutationA", {
      ...payload,
      actionGroup,
    });
    commit("mutationB", {
      someProp: true,
      actionGroup,
    });
  },
};

Undo/redo stack illustration

// After dispatching 'myAction' once
done = [
  { type: "mutationA", payload: { ...payload, actionGroup: "myAction" } },
  { type: "mutationB", payload: { someProp: true, actionGroup: "myAction" } },
];
undone = [];

// After dispatching 'undo'
done = [];
undone = [
  { type: "mutationA", payload: { ...payload, actionGroup: "myAction" } },
  { type: "mutationB", payload: { someProp: true, actionGroup: "myAction" } },
];

# Working with undo/redo on mutations produced by side effects (i.e. API/database calls)

In Vue.js apps, Vuex mutations are often committed inside actions that contain asynchronous calls to an API/database service: For instance, commit("list/addItem", item) could be called after an axios request to PUT https://<your-rest-api>/v1/list. When undoing the commit("list/addItem", item) mutation, an appropriate API call is required to DELETE this item. The inverse also applies if the first API call is the DELETE method (PUT would have to be called when the commit("list/removeItem", item) is undone). View the unit test for this feature here.

This scenario can be implemented by providing the respective action names as the undoCallback and redoCallback fields in the mutation payload (NB: the payload object should be parameterized as an object literal):

const actions = {
  saveItem: async (({ commit }), item) => {
    await axios.put(PUT_ITEM, item);
    commit("addItem", {
      item,
      // dispatch("deleteItem", { item }) on undo()
      undoCallback: "deleteItem",
      // dispatch("saveItem", { item }) on redo()
      redoCallback: "saveItem"
    });
  },
  deleteItem: async (({ commit }), item) => {
    await axios.delete(DELETE_ITEM, item);
    commit("removeItem", {
      item,
      // dispatch("saveItem", { item }) on undo()
      undoCallback: "saveItem",
      // dispatch("deleteItem", { item }) on redo()
      redoCallback: "deleteItem"
    });
  }
};

const mutations = {
  // NB: payload parameters as object literal props
  addItem: (state, { item }) => {
    // adds the item to the list
  },
  removeItem: (state, { item }) => {
    // removes the item from the list
  }
};

# Clearing the undo/redo stacks with the `clear` action

The internal done and undone stacks used to track mutations in the vuex store/modules can be cleared (i.e. emptied) with the clear action. This action is scaffolded when using scaffoldActions(actions) of scaffoldStore(store). This enhancement is described further in issue #7, with accompanying unit tests.

/**
 * Current done stack: [mutationA, mutation B]
 * Current undone stack: [mutationC]
 **/
this.$store.dispatch("list/clear");

await this.$nextTick();
/**
 * Current done stack: []
 * Current undone stack: []
 **/

# Resetting the current state with the `reset` action

Unlike the clear action, reset empties the done and undone stacks, but maintains the state of the store up to this particular point. This action is scaffolded when using scaffoldActions(actions) of scaffoldStore(store). This enhancement is described further in issue #13, with accompanying unit tests.

/**
 * Current done stack: [mutationA, mutation B]
 * Current undone stack: [mutationC]
 **/
this.$store.dispatch("list/reset");

await this.$nextTick();
/**
 * Current done stack: []
 * Current undone stack: []
 * state: resetState (i.e. initial state + mutationA + mutationB)
 **/

# Inspecting `done` and `undone` mutations

Some vuex powered applications may require knowledge of the done and undone stacks, e.g. to preserve undo/redo functionality between page loads. The following configuration exposes the stacks by scaffoling a undoRedoConfig object in the store or module which uses the plugin:

import Vuex from "vuex";
import undoRedo, { scaffoldStore } from "undo-redo-vuex";

// state, getters, actions & mutations ...

// boolean flag to expose done and undone stacks
const exposeUndoRedoConfig = true;

const storeConfig = scaffoldStore({
  state,
  actions,
  mutations
}, exposeUndoRedoConfig); // boolean flag as the second optional param

/**
 * NB: When configuring state, actions or mutations with scaffoldState,
 * scaffoldActions or scaffoldMutations, the exposeUndoRedoConfig = true
 * flag should be passed as the second param.
 */ 

const store = new Vuex.Store({
  ...storeConfig,
  plugins: [
    // Pass boolean flag as an named option
    undoRedo({ exposeUndoRedoConfig })
  ]
});

To access the exposed done and undone stacks, e.g. in a component:

const { done, undone } = this.$store.state;

This enhancement is described further in issue #45, with accompanying unit tests.

← Installation Testing and test scenarios →

# Usage

# How to use it in your store module

# Setting up emptyState and resetState mutations

# Setup the store plugin

# Accessing canUndo and canRedo properties

# Undoing actions with actionGroups