https://github.com/jaredhanson/node-parent-require
Require modules from parent modules.
https://github.com/jaredhanson/node-parent-require
Last synced: 8 months ago
JSON representation
Require modules from parent modules.
- Host: GitHub
- URL: https://github.com/jaredhanson/node-parent-require
- Owner: jaredhanson
- License: mit
- Created: 2013-08-08T02:58:11.000Z (over 12 years ago)
- Default Branch: master
- Last Pushed: 2013-08-12T19:48:57.000Z (over 12 years ago)
- Last Synced: 2025-04-09T00:51:11.283Z (9 months ago)
- Language: JavaScript
- Size: 125 KB
- Stars: 34
- Watchers: 6
- Forks: 5
- Open Issues: 3
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# parent-require
[](http://travis-ci.org/jaredhanson/node-parent-require)
[](https://coveralls.io/r/jaredhanson/node-parent-require)
[](http://david-dm.org/jaredhanson/node-parent-require)
Require modules from parent (i.e. loading) module.
## Install
$ npm install parent-require
## Usage
`parent-require` addresses an annoying error condition that arises when
developing plugins, which have [peer dependencies](http://blog.nodejs.org/2013/02/07/peer-dependencies/),
that are `npm link`'d into an application.
The problem is best illustrated by example. We'll use a shared package of [Mongoose](http://mongoosejs.com/)
schemas, but the concept applies equally well to any module you plugin to a
larger framework.
#### Develop a Plugin for a Framework
Let's develop a set of shared [Mongoose](http://mongoosejs.com/) schemas for a
user database, packaged as `mongoose-schemas-users` for reuse by any application
that needs to query the database.
```javascript
var mongoose = require('mongoose');
var UserSchema = new mongoose.Schema(...);
module.exports = UserSchema;
```
The important bit here is that `mongoose` is a *peer dependency* of this
package.
#### Require a Plugin from an App
Now, let's install this package...
npm install mongoose-schemas-users
..and require it within our application:
```javascript
var mongoose = require('mongoose')
, schemas = require('mongoose-schemas-users')
mongoose.model('User', schemas.UserSchema);
```
So far, so good.
#### npm link Plugin for Development
During the course of developing the application, we discover that we need to
tweak the schemas we've defined. This is usually easy:
npm link mongoose-schemas-users
We've made some edits, and run the application:
Error: Cannot find module 'mongoose'
WTF?!? This issue arises because `mongoose` is a *peer dependency*. Now that
it has been `npm link`'d to a directory that resides outside of the application
itself, Node's typical resolution algorithm fails to find it.
#### Fallback to Parent Require
This is where `parent-require` comes into play. It provides a fallback to
`require` modules from the *loading* (aka parent) module. Because the loading
module exists within the application itself, Node's resolution algorithm will
correctly find our peer dependency.
```javascript
try {
var mongoose = require('mongoose');
} catch (_) {
// workaround when `npm link`'ed for development
var prequire = require('parent-require')
, mongoose = prequire('mongoose');
}
var UserSchema = new mongoose.Schema(...);
module.exports = UserSchema;
```
With the fallback in place, we can both `npm install` and `npm link` this
plugin, correctly resolving peer dependencies in both cases.
## Tests
$ npm install
$ npm test
## Credits
- [Jared Hanson](http://github.com/jaredhanson)
## License
[The MIT License](http://opensource.org/licenses/MIT)
Copyright (c) 2013 Jared Hanson <[http://jaredhanson.net/](http://jaredhanson.net/)>