express-request-parameters
v0.2.2
Published
Middleware for processing request data (setting default values, filtering, validation)
Downloads
16
Maintainers
Readme
express-request-parameters
Middleware for processing request data (setting default values, filtering, validation). It's useful in HTTP API when you want to process client input. The processing itself is performed by transformer-chain module.
Note: This module works in Node.js >= 4.0.
Installation
npm install express-request-parameters
Usage
expressRequestParameters(schema, [options])
Parameters
schema
(Function | Object) - Schema which defines how to process request data (req.query, req.body and req.params are merged and processed as one object)[options]
(Object)[name=parameters]
(String) - Specifies where to set processed data inreq
object[rawName=rawParameters]
(String) - Specifies where to set raw data (before processing) inreq
object[errorFactory]
(Function) - Factory for error creation on validation error[errorMessage=Bad Request]
(String | Function) - Error message
Return value
(Function) - (req, res, next) middleware
Overview
Imagine you want to allow users to create books in your REST API. And book looks like this:
const book = {
name: 'The Adventures of Tom Sawyer', // required field
author: {
name: 'Mark Twain' // required
},
reviews: [
{
author: 'Leo Tolstoy',
text: 'Great novel',
visible: true
},
{
author: 'Fyodor Dostoyevsky',
text: 'Very interesting'
}
]
};
And before creating book you may want to check that client sent valid data. You can do it by defining schema (take a look at transformer-chain to see all features).
const bookSchema = {
name: {
$filter: 'trim', // trims only strings
$validate: {
required: true, // mark as required field
string: true
}
},
author: {
$validate: { // you can omit check that "author" value is object, it will be done internally
required: true
},
name: {
$filter: 'trim',
$validate: {
required: true,
string: true
}
}
},
reviews: [{ // define schema for array items
author: {
$filter: 'trim',
$validate: {
required: true,
string: true
}
},
text: {
$filter: 'trim',
$validate: {
required: true,
string: true
}
},
visible: {
$default: true, // default value will be set when actual value of property is undefined
$filter: 'toBoolean' // always returns boolean
}
}]
};
Then you need just pass this schema to express-request-parameters
:
const express = require('express');
const parameters = require('express-request-parameters');
const bookSchema = require('./bookSchema');
const app = express();
app.post('/books', parameters(bookSchema), function(req, res, next) {
// req.parameters is processed input data
});
If you want to use another from parameters
name just use name
option:
app.post('/books', parameters(bookSchema, { name: 'book' }), function(req, res, next) {
// use req.book instead of req.parameters
});
You can specify default options:
// config.js
const parameters = require('express-request-parameters');
parameters.options = {
name: '$params'
};
// app.js
app.post('/books', parameters(bookSchema), function(req, res, next) {
// use req.$params instead of req.parameters
});
When you have validation error middleware will call next
with error object which looks like this:
const err = new Error('Bad Request');
err.status = 400;
err.errors = errors; // validation errors
You can change error message (Bad Request
) by using errorMessage
option:
// config.js
const parameters = require('express-request-parameters');
parameters.options = {
errorMessage: 'Validation Error'
};
// or it can be a function
parameters.options = {
errorMessage: function(req) { // you can use req object if needed
return 'Validation Error';
}
};
Or you can even specify your custom errorFactory
:
// config.js
const parameters = require('express-request-parameters');
parameters.options = {
errorFactory: function(message, validationErrors) {
const err = new Error(message);
err.status = 400;
err.validationErrors = validationErrors;
return err;
}
};
If you need to do something with validators/filters (add new for example), you can use transformer
:
const parameters = require('express-request-parameters');
parameters.transformer.plugins.validate.validators.newValidator = function(value, options) {
/* validator implementation */
};
Tests
npm install
npm test