strummer-middleware

Description

Wraps your strummer validation logic into middleware ready for a HTTP request!

Usage

npm install strummer-middleware --save

var s = require('strummer');
var sware = require('strummer-middleware');

var validate = sware({
  body: s({ id: 'uuid', name: 'string', age: 'number' })
});

server.post('/users', validate, controller);

strummer-middleware can validate 4 areas of the request:

sware({
  params:   /* match req.params    */
  query:    /* match req.query    */
  body:     /* match req.body     */
  headers:  /* match req.headers  */
})

These fields were chosen because they are a well established standard. strummer-middleware is not responsible for creating req.params, req.query or req.body, you must follow the documentation of your web framework.

Custom fields can be added using the method setValidationArea(name, errorString). For example:

sware.setValidationArea('jwt', 'Invalid JWT');
sware({
  jwt: {
    'iss': 'string'
  }
})

Error handling

strummer-middleware will call next(err) in case of validation errors. In Express this means you will also need to set up an error handler.

function errorHandler(err, req, res, next) {
  res.statusCode(400).send('Bad request')
}

// global handler
server.use(errorHandler)

// or local handler
server.post('/users', validation, errorHandler, controller)

The err object also contains more information:

console.log(err.message)
console.log(err.details)

Strummer integration

Note that strummer is not included in package.json as a dependency, peerDependency or devDependency. This is to ensure we stay compatible with most versions of Node.

It also makes it very obvious which version of strummer you are using. For example, if strummer-middleware bundled its own version the following code would be quite confusing:

var s = require('strummer')

sware({
  body: {
    name: 'string',    // would use the built-in version
    age: s.custom()    // would use the provided version
  }
})

Instead of strummer, you can also choose to use a custom validation library, as long as matchers have a .match(path, value) function that returns an array.