12

I want to create a piece of express middleware looks something like this:

function validate (options) {
  var defaultOptions = {...}
  , validations = _.extend(defaultOptions, options);
  return validate (req, res, next) {
      /* Use some sort of validation framework where I can pass `validations` into*/



      next(someErrors || null)
  }    
}

I've looked at both node-validator with the middleware option as well as tracery but neither of them looked like you could pass a "rule set" into them and have them run the rules against a provided input.

Does anyone have any suggestions on how to do this with either of those modules or with another one that I haven't found yet? Am I going to have to roll my own to do this?

UPDATE

This is indeed to validate form posts. I know there won't be a single piece of middleware that will cover all of the posts for the whole site; this will be used only for certain routes. I want reusable middleware because we are making APIs that have common routes and expect common form bodies that we want to validate in similar fashion with the option to tweak that on a per API basis.

arb
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  • Maybe I'm being slow. My first impression was this was to validate form posts, but I don't really see that an app-wide middleware is the right place to put that logic. Are you trying to detect CSRF attacks? – Richard Marr May 23 '13 at 15:46

3 Answers3

5

Using JSON schema

Without knowing any more about the specific things you'd like to check for, I think tools based on JSON schema could serve you pretty well. JSON schema specifies many kinds of validation rules.

Examples of node modules:

I made this list based on a simple search for "json schema" on Nipster. I find Nipster is a great tool to get a quick overview of good modules for a particular task because it also includes number of forks and github stars of the project as a gauge for popularity, which in turn often says something about a module's quality and maturity. Of course not to be taken blindly, but as a start for further research.

I expect that actual not all modules for JSON schema have support for all validation rules, so I think you should start by inventorying what kind of rules you actually need (or would like to have available in the future), then narrow down your selection based on that.

There's an official test suite for JSON schema tools. You may want to look for modules that advertise compliance with this suite.

Not using JSON schema

Myrne Stol
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  • I know about the JSON schema validation, but that isn't really where I'd like to go with this. I'm looking to do simple JS object validation. I'm also not a huge fan of the JSON schema validation spec because I found it very difficult for humans to read. – arb May 29 '13 at 21:54
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    You ought to have mentioned that in your question. It would have saved me work. How about using [Orderly](http://orderly-json.org/) as base syntax? You can try it with http://zaach.github.io/orderly.js/ . – Myrne Stol May 29 '13 at 21:57
  • there now a project to plug json schemas in *Joi*, named *enjoi*: https://github.com/tlivings/enjoi – AdrieanKhisbe Mar 09 '15 at 13:45
3

You may want to use a pattern like this:

function validateRegForm(req, res, next){
  console.log('Validating form...');
  if(!req.body.password){
    return res.send(500, 'Need a password');
  };
  next();
};

app.post('/regForm'
, validateRegForm
, function(req,res){
  // If Express calls this fn, the previous fn did next(), not res.send()
  console.log('Doing something with this valid form');
  res.redirect('/regForm/complete');
});
Plato
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    I would count this as "rolling your own" which I would really like to avoid doing. This is how it is now and I'm trying to clean it up. – arb Jun 01 '13 at 20:58
  • I don't know of a lower-overhead way to add reusable middleware functions to particular routes. At some point you are going to have to write the code to handle different validation situations differently. Regardless of if you roll your own or find a library, this pattern might still be useful to allow you to reuse those validation functions on different routes. gl – Plato Jun 01 '13 at 22:49
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    I think this is a very good answer. The rule-set you are talking about can be modelled as if-else ladders or conditional expressions. You just need to put them in your own middleware, and that will be it. – kumarharsh Jun 05 '13 at 12:59
0

I know this is old, but for those of you looking for a great way to validate incoming request bodies, as well as headers, route params, and query parameters, check out https://github.com/continuationlabs/celebrate.

It leverages Joi to validate arguments which has a declarative way to reuse and extend validation rules.

arb
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