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Mongoose Patch History is a mongoose plugin that saves a history of [JSON Patch](http://jsonpatch.com/) operations for all documents belonging to a schema in an associated "patches" collection.
## Installation
$ npm install mongoose-patch-history
## Usage
To use **mongoose-patch-history** for an existing mongoose schema you can simply plug it in. As an example, the following schema definition defines a `Post` schema, and uses mongoose-patch-history with default options:
```javascript
import mongoose, { Schema } from 'mongoose'
import patchHistory from 'mongoose-patch-history'
/* or the following if not running your app with babel:
const patchHistory = require('mongoose-patch-history').default;
const mongoose = require('mongoose');
const Schema = mongoose.Schema;
*/
const PostSchema = new Schema({
title: { type: String, required: true },
comments: Array,
})
PostSchema.plugin(patchHistory, { mongoose, name: 'postPatches' })
const Post = mongoose.model('Post', PostSchema)
```
**mongoose-patch-history** will define a schema that has a `ref` field containing the `ObjectId` of the original document, a `ops` array containing all json patch operations and a `date` field storing the date where the patch was applied.
### Storing a new document
Continuing the previous example, a new patch is added to the associated patch collection whenever a new post is added to the posts collection:
```javascript
Post.create({ title: 'JSON patches' })
.then(post => post.patches.findOne({ ref: post.id }))
.then(console.log)
// {
// _id: ObjectId('4edd40c86762e0fb12000003'),
// ref: ObjectId('4edd40c86762e0fb12000004'),
// ops: [
// { value: 'JSON patches', path: '/title', op: 'add' },
// { value: [], path: '/comments', op: 'add' }
// ],
// date: new Date(1462360838107),
// __v: 0
// }
```
### Updating an existing document
**mongoose-patch-history** also adds a static field `Patches` to the model that can be used to access the patch model associated with the model, for example to query all patches of a document. Whenever a post is edited, a new patch that reflects the update operation is added to the associated patch collection:
```javascript
const data = {
title: 'JSON patches with mongoose',
comments: [{ message: 'Wow! Such Mongoose! Very NoSQL!' }],
}
Post.create({ title: 'JSON patches' })
.then(post => post.set(data).save())
.then(post => post.patches.find({ ref: post.id }))
.then(console.log)
// [{
// _id: ObjectId('4edd40c86762e0fb12000003'),
// ref: ObjectId('4edd40c86762e0fb12000004'),
// ops: [
// { value: 'JSON patches', path: '/title', op: 'add' },
// { value: [], path: '/comments', op: 'add' }
// ],
// date: new Date(1462360838107),
// __v: 0
// }, {
// _id: ObjectId('4edd40c86762e0fb12000005'),
// ref: ObjectId('4edd40c86762e0fb12000004'),
// ops: [
// { value: { message: 'Wow! Such Mongoose! Very NoSQL!' }, path: '/comments/0', op: 'add' },
// { value: 'JSON patches with mongoose', path: '/title', op: 'replace' }
// ],
// "date": new Date(1462361848742),
// "__v": 0
// }]
```
### Rollback to a specific patch
```javascript
rollback(ObjectId, data, save)
```
Documents have a `rollback` method that accepts the _ObjectId_ of a patch doc and sets the document to the state of that patch, adding a new patch to the history.
```javascript
Post.create({ title: 'First version' })
.then(post => post.set({ title: 'Second version' }).save())
.then(post => post.set({ title: 'Third version' }).save())
.then(post => {
return post.patches
.find({ ref: post.id })
.then(patches => post.rollback(patches[1].id))
})
.then(console.log)
// {
// _id: ObjectId('4edd40c86762e0fb12000006'),
// title: 'Second version',
// __v: 0
// }
```
#### Injecting data
Further the `rollback` method accepts a _data_ object which is injected into the document.
```javascript
post.rollback(patches[1].id, { name: 'merged' })
// {
// _id: ObjectId('4edd40c86762e0fb12000006'),
// title: 'Second version',
// name: 'merged',
// __v: 0
// }
```
#### Rollback without saving
To `rollback` the document to a specific patch but without saving it back to the database call the method with an empty _data_ object and the save flag set to false.
```javascript
post.rollback(patches[1].id, {}, false)
// Returns the document without saving it back to the db.
// {
// _id: ObjectId('4edd40c86762e0fb12000006'),
// title: 'Second version',
// __v: 0
// }
```
The `rollback` method will throw an Error when invoked with an ObjectId that is
- not a patch of the document
- the latest patch of the document
## Options
```javascript
PostSchema.plugin(patchHistory, {
mongoose,
name: 'postPatches',
})
```
- `mongoose` :pushpin: _required_
The mongoose instance to work with
- `name` :pushpin: _required_
String where the names of both patch model and patch collection are generated from. By default, model name is the pascalized version and collection name is an undercore separated version
- `removePatches`
Removes patches when origin document is removed. Default: `true`
- `transforms`
An array of two functions that generate model and collection name based on the `name` option. Default: An array of [humps](https://github.com/domchristie/humps).pascalize and [humps](https://github.com/domchristie/humps).decamelize
- `includes`
Property definitions that will be included in the patch schema. Read more about includes in the next chapter of the documentation. Default: `{}`
- `excludes`
Property paths that will be excluded in patches. Read more about excludes in the [excludes chapter of the documentation](https://github.com/codepunkt/mongoose-patch-history#excludes). Default: `[]`
- `trackOriginalValue`
If enabled, the original value will be stored in the change patches under the attribute `originalValue`. Default: `false`
### Includes
```javascript
PostSchema.plugin(patchHistory, {
mongoose,
name: 'postPatches',
includes: {
title: { type: String, required: true },
},
})
```
This will add a `title` property to the patch schema. All options that are available in mongoose's schema property definitions such as `required`, `default` or `index` can be used.
```javascript
Post.create({ title: 'Included in every patch' })
.then((post) => post.patches.findOne({ ref: post.id })
.then((patch) => {
console.log(patch.title) // 'Included in every patch'
})
```
The value of the patch documents properties is read from the versioned documents property of the same name.
#### Reading from virtuals
There is an additional option that allows storing information in the patch documents that is not stored in the versioned documents. To do so, you can use a combination of [virtual type setters](http://mongoosejs.com/docs/guide.html#virtuals) on the versioned document and an additional `from` property in the include options of **mongoose-patch-history**:
```javascript
// save user as _user in versioned documents
PostSchema.virtual('user').set(function (user) {
this._user = user
})
// read user from _user in patch documents
PostSchema.plugin(patchHistory, {
mongoose,
name: 'postPatches',
includes: {
user: { type: Schema.Types.ObjectId, required: true, from: '_user' },
},
})
// create post, pass in user information
Post.create({
title: 'Why is hiring broken?',
user: mongoose.Types.ObjectId(),
})
.then(post => {
console.log(post.user) // undefined
return post.patches.findOne({ ref: post.id })
})
.then(patch => {
console.log(patch.user) // 4edd40c86762e0fb12000012
})
```
In case of a rollback in this scenario, the `rollback` method accepts an [object as its second parameter](https://github.com/codepunkt/mongoose-patch-history#injecting-data) where additional data can be injected:
```javascript
Post.create({ title: 'v1', user: mongoose.Types.ObjectId() })
.then(post =>
post
.set({
title: 'v2',
user: mongoose.Types.ObjectId(),
})
.save()
)
.then(post => {
return post.patches.find({ ref: post.id }).then(patches =>
post.rollback(patches[0].id, {
user: mongoose.Types.ObjectId(),
})
)
})
```
#### Reading from query options
In situations where you are running Mongoose queries directly instead of via a document, you can specify the extra fields in the query options:
```javascript
Post.findOneAndUpdate(
{ _id: '4edd40c86762e0fb12000012' },
{ title: 'Why is hiring broken? (updated)' },
{ _user: mongoose.Types.ObjectId() }
)
```
### Excludes
```javascript
PostSchema.plugin(patchHistory, {
mongoose,
name: 'postPatches',
excludes: [
'/path/to/hidden/property',
'/path/into/array/*/property',
'/path/to/one/array/1/element',
],
})
// Properties
// /path/to/hidden: included
// /path/to/hidden/property: excluded
// /path/to/hidden/property/nesting: excluded
// Array element properties
// /path/into/array/0: included
// /path/into/array/345345/property: excluded
// /path/to/one/array/0/element: included
// /path/to/one/array/1/element: excluded
```
This will exclude the given properties and _all nested_ paths. Excluding `/` however will not work, since then you can just disable the plugin.
- If a property is `{}` or `undefined` after processing all excludes statements, it will _not_ be included in the patch.
- Arrays work a little different. Since json-patch-operations work on the array index, array elements that are `{}` or `undefined` are still added to the patch. This brings support for later `remove` or `replace` operations to work as intended.
The `ARRAY_WILDCARD` `*` matches every array element.
If there are any bugs experienced with the `excludes` feature please write an issue so we can fix it!