get-param

Express.js get parameter middleware.

Installation

npm install express-get-param

or

yarn add express-get-param

Basic Usage

const express = require('express')
const app = express()
const getParam = require('express-get-param')

app.use(getParam('parameterName', {options}))
or
app.get('/', getParam('parameterName, {Options}), controller)

What is this about and why?

This is a middleware which allows you to extract parameter value from request parameters, headers, query string, or body. It's like the old time req.param in Express.js 3 but more powerful.

Compare with express-param, defining controller related parameters in the route file will definitely improve the code readability.

Example:

Before:

//route.js
router.get('/api/page/:pageName', Contraller.pageList)

//controller.js
(req, res)=>{
   const pageName = req.param('pageName')
   const limit = req.query.limit || 0
   const skip = req.query.skip || 0
   // Probably more query parameters I will take....
   ...
}

After:

//route.js

...
router.get('/api/page/:pageName',
	getParam('limit'),
	getParam('skip'),
	Contraller.pageList)

//controller.js
(req, res)=>{
	const { limit, skip, pageName } = res.locals
   ...
}

The parameters Fetching Order

• URL Parameters: https://expressjs.com/en/api.html#req.params
• Headers: https://expressjs.com/en/api.html#req.get
• Query String: https://expressjs.com/en/api.html#req.query
• Body: https://expressjs.com/en/api.html#express.json https://expressjs.com/en/api.html#req.body

Additional Options

• parser (String or Function): Parse raw parameter value

  • String

    • getParam.STRING
    • getParam.INTEGER
    • getParam.DATE
      • Note: getParam.DATE will parse the date string into a moment object
    • getParam.ARRAY
      • Note: getParam.ARRAY will parse comma-separated string into array

  • Function:

    • return: parsed value

    getParam('paramName', {parser:(paramValue)=>{return paramValue}})

• validator (Function): Validate raw parameter value - return: boolean -

• validationError (Function):

• alias (String): The name which will be used to save to res.locals

  getParam('paramName', {alias: 'paramName2'})
  ...//in later routes
  const param = res.locals.paramName2

Env Vars

• SUPPRESS_GET_PARAM_WARNING: Disable all warnings (Default: false)

Debugging

Use environment DEBUG to show debug logs

DEBUG=get-param:*

Testing

npm run test