underscore-db
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Use JavaScript objects as databases
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# underscore-db [](https://travis-ci.org/typicode/underscore-db) [](http://badge.fury.io/js/underscore-db)
> Adds functions to Underscore/Lodash for manipulating database-like objects.
It adds:
* `getById`
* `insert`
* `upsert`
* `updateById`
* `updateWhere`
* `replaceById`
* `removeById`
* `removeWhere`
* `save`
* `load`
* `createId`
Data can be persisted using the filesystem or localStorage.
__[Live example](http://typicode.github.io/underscore-db/)__
__Tip__ You can extend [lowdb](https://github.com/typicode/lowdb) with underscore-db.
## Install
__Node__
```bash
$ npm install lodash underscore-db
```
```javascript
var _ = require('lodash');
var _db = require('underscore-db');
_.mixin(_db);
```
__Tip__ underscore-db is also compatible with underscore
## Usage example
Create an empty database object
```javascript
var db = {
posts: []
}
```
Create a post
```javascript
var newPost = _.insert(db.posts, {title: 'foo'});
```
Display database `console.log(db)`
```javascript
{
posts: [
{title: "foo", id: "5ca959c4-b5ab-4336-aa65-8a197b6dd9cb"}
]
}
```
Retrieve post using underscore-db `get` or underscore `find` method
```javascript
var post = _.getById(db.posts, newPost.id);
var post = _.find(db.posts, function(post) {
return post.title === 'foo'
});
```
Persist
```javascript
_.save(db);
```
## API
The following database object is used in API examples.
```javascript
var db = {
posts: [
{id: 1, body: 'one', published: false},
{id: 2, body: 'two', published: true}
],
comments: [
{id: 1, body: 'foo', postId: 1},
{id: 2, body: 'bar', postId: 2}
]
}
```
__getById(collection, id)__
Finds and returns document by id or undefined.
```javascript
var post = _.getById(db.posts, 1);
```
__insert(collection, document)__
Adds document to collection, sets an id and returns created document.
```javascript
var post = _.insert(db.posts, {body: 'New post'});
```
If the document already has an id, and it is the same as an existing document in the collection, an error is thrown.
```javascript
_.insert(db.posts, {id: 1, body: 'New post'});
_.insert(db.posts, {id: 1, title: 'New title'}); // Throws an error
```
__upsert(collection, document)__
Adds document to collection, sets an id and returns created document.
```javascript
var post = _.upsert(db.posts, {body: 'New post'});
```
If the document already has an id, it will be used to insert or replace.
```javascript
_.upsert(db.posts, {id: 1, body: 'New post'});
_.upsert(db.posts, {id: 1, title: 'New title'});
_.getById(db.posts, 1); // {id: 1, title: 'New title'}
```
__updateById(collection, id, attrs)__
Finds document by id, copies properties to it and returns updated document or undefined.
```javascript
var post = _.updateById(db.posts, 1, {body: 'Updated body'});
```
__updateWhere(collection, whereAttrs, attrs)__
Finds documents using `_.where`, updates documents and returns updated documents or an empty array.
```javascript
// Publish all unpublished posts
var posts = _.updateWhere(db.posts, {published: false}, {published: true});
```
__replaceById(collection, id, attrs)__
Finds document by id, replaces properties and returns document or undefined.
```javascript
var post = _.replaceById(db.posts, 1, {foo: 'bar'});
```
__removeById(collection, id)__
Removes document from collection and returns it or undefined.
```javascript
var comment = _.removeById(db.comments, 1);
```
__removeWhere(collection, whereAttrs)__
Removes documents from collection using `_.where` and returns removed documents or an empty array.
```javascript
var comments = _.removeWhere(db.comments, {postId: 1});
```
__save(db, [destination])__
Persists database using localStorage or filesystem. If no destination is specified it will save to `db` or `./db.json`.
```javascript
_.save(db);
_.save(db, '/some/path/db.json');
```
__load([source])__
Loads database from localStorage or filesystem. If no source is specified it will load from `db` or `./db.json`.
```javascript
var db = _.load();
var db = _.load('/some/path/db.json');
```
__id__
Overwrite it if you want to use another id property.
```javascript
_.id = '_id';
```
__createId(collectionName, doc)__
Called by underscore-db when a document is inserted. Overwrite it if you want to change id generation algorithm.
```javascript
_.createId = function(collectionName, doc) {
return collectionName + '-' + doc.name + '-' + _.random(1, 9999);
}
```
## FAQ
### How to query?
Everything you need for querying is present in Underscore and Lodash: `where`, ```find```, ```map```, ```reduce```, ```filter```, ```reject```, ```sortBy```, ```groupBy```, ```countBy```, ...
See http://lodash.com/docs or http://underscorejs.org.
Example:
```javascript
// Using Underscore
var topFivePosts = _(db.posts)
.chain()
.where({published: true})
.sortBy(function(post) {
return post.views;
})
.first(5)
.value();
// Using Lodash
var topFivePosts = _(db.posts)
.where({published: true})
.sortBy('views')
.first(5)
.value();
```
### How to reduce file size?
With Lodash, you can create custom builds and include just what you need.
```bash
$ npm install -g lodash-cli
$ lodash include=find,forEach,indexOf,filter,has
```
For more build options, see http://lodash.com/custom-builds.
## Changelog
See details changes for each version in the [release notes](https://github.com/typicode/underscore-db/releases).
## License
underscore-db is released under the MIT License.