Express JS equivalent of decorator pattern from Python frameworks

Question

Working with Express js to write a simple NodeJS webservice. I'm historically a python guy.

In frameworks like Django or Flask, its common to see Python decorators used to implement logic from plugins only on specific endpoints. An example of this pattern can be seen here.

http://pythonhosted.org/Flask-Classy/#using-multiple-routes-for-a-single-view

I'm working on an Express middleware and have everything working well with the app.use 3-parity function, but this is only relevant for logic executes for every request. I'd like to allow the end user of the plugin to run parcels of my logic (already in separate functions) only on specific endpoints similar to the pattern outlined in the source above.

Some of the configuration to these wrappers would be passed at app start.

What would be the best approach to this? Should I emulate this pattern with functions that take the actual route handler as an argument and return it at end? Something like this?

function pluginWrapper(endptFunc){
    //plugin logic here
    return endptFunc;
  }

  app.get('/endpt', pluginWrapper(function(req,res,next){
    //endpt logic here
    res.end()
  }));

Answer 1

Here are the express idiomatic strategies:

1. Things relavent for the majority of requests across the entire site become normal connect middleware: app.use(express.cookieParser())
2. Things relavent for just a particular route can go just on that route: app.post('/users', express.bodyParser(), createUser). This is the pattern I think that most closely matches your above scenario
3. Groups of related middleware can be passed as lists: app.get('/books', [paginate, queryLimit, memoize], getBooks). And of course that list could be a variable or module and thus shared in a DRY fashion.
4. Common functionality triggered by patterns in the path itself can use app.param: app.get('/:username/hobbies', getHobbies)
5. Existing regular functions can be wrapped into middleware to adapt them to a middleware API.
6. You can just call functions as normal. Not every method of code reuse has to be shoehorned into one of express's convenient patterns.

To address your question more directly, I don't think you should try to port the python decorator pattern 1-to-1 to javascript. Middleware accomplishes essentially the same thing. If you post concrete examples using decorators, we can suggest an idiomatic way to implement them in express.