# parent-require
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[](http://travis-ci.org/jaredhanson/node-parent-require)
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[](https://coveralls.io/r/jaredhanson/node-parent-require)
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[](http://david-dm.org/jaredhanson/node-parent-require)
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Require modules from parent (i.e. loading) module.
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## Install
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$ npm install parent-require
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## Usage
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`parent-require` addresses an annoying error condition that arises when
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developing plugins, which have [peer dependencies](http://blog.nodejs.org/2013/02/07/peer-dependencies/),
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that are `npm link`'d into an application.
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The problem is best illustrated by example. We'll use a shared package of [Mongoose](http://mongoosejs.com/)
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schemas, but the concept applies equally well to any module you plugin to a
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larger framework.
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#### Develop a Plugin for a Framework
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Let's develop a set of shared [Mongoose](http://mongoosejs.com/) schemas for a
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user database, packaged as `mongoose-schemas-users` for reuse by any application
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that needs to query the database.
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```javascript
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var mongoose = require('mongoose');
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var UserSchema = new mongoose.Schema(...);
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module.exports = UserSchema;
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```
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The important bit here is that `mongoose` is a *peer dependency* of this
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package.
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#### Require a Plugin from an App
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Now, let's install this package...
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npm install mongoose-schemas-users
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..and require it within our application:
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```javascript
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var mongoose = require('mongoose')
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, schemas = require('mongoose-schemas-users')
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mongoose.model('User', schemas.UserSchema);
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```
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So far, so good.
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#### npm link Plugin for Development
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During the course of developing the application, we discover that we need to
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tweak the schemas we've defined. This is usually easy:
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npm link mongoose-schemas-users
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We've made some edits, and run the application:
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Error: Cannot find module 'mongoose'
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WTF?!? This issue arises because `mongoose` is a *peer dependency*. Now that
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it has been `npm link`'d to a directory that resides outside of the application
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itself, Node's typical resolution algorithm fails to find it.
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#### Fallback to Parent Require
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This is where `parent-require` comes into play. It provides a fallback to
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`require` modules from the *loading* (aka parent) module. Because the loading
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module exists within the application itself, Node's resolution algorithm will
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correctly find our peer dependency.
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```javascript
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try {
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var mongoose = require('mongoose');
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} catch (_) {
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// workaround when `npm link`'ed for development
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var prequire = require('parent-require')
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, mongoose = prequire('mongoose');
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}
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var UserSchema = new mongoose.Schema(...);
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module.exports = UserSchema;
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```
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With the fallback in place, we can both `npm install` and `npm link` this
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plugin, correctly resolving peer dependencies in both cases.
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## Tests
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$ npm install
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$ npm test
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## Credits
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- [Jared Hanson](http://github.com/jaredhanson)
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## License
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[The MIT License](http://opensource.org/licenses/MIT)
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Copyright (c) 2013 Jared Hanson <[http://jaredhanson.net/](http://jaredhanson.net/)>
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