Express js 从根 URL 获取参数（不像 req.params 那么简单）

Question

I've made an api and I've routed it as follows:

In the main routes file:

  //with sub-route
  app.use('/api/test/:test', require('./api/test'));

  //Without sub-route
  app.use('/api/test2/:test', function(req, res){
    console.log('in test', req.params, req.body);
    return res.status(200).json({params: req.params, body: req.body});
  });

Accessing the second route displays the :test in req.params, as expected.

In the modular routes folder ('./api/test') I have a sub-router (index.js) which looks like this:

router.get('/:test2', controller.getItem);

with a handler:

exports.getItem = function getItem(req, res) {
  console.log('in getItem \nreq.params', req.params, '\nreq.body: ', req.body);
  return res.status(200).json({yes: 'yes', params: req.params, body: req.body});
};

So the first url , which has no sub-routing is: /api/test2/:test and logs out whatever you put in place of :test in req.params.

The second url , which has sub-routing is: /api/test/:test/:test2 , but when you send your get request only :test2 appears in req.params .

It seems that if you use this pattern any variables in the 'root' of the route (ie in the primary router) are not picked up.

Is there a way to fix this?

Thanks

Answer 1

You will need a middleware to fix this for you:

function paramFix(req, res, next) {
    req._params = req.params;
    next();
}
app.use('/api/test/:test', paramFix, require('./api/test'));

And then use req._params.test in your last callback function.

So reflect multiple levels of mounting you can extend your middleware like this:

function paramFix(req, res, next) {
    req._params = req._params || {};
    for (var key in req.params) {
        if (req.params.hasOwnProperty(key)) {
            req._params[key] = req.params[key];
        }
    }
    next();
}
app.use('/api/test/:test', paramFix, require('./api/test'));

Answer 2

express.js (>= v4.5.0+) provides a direct solution without having to implement middleware. https://expressjs.com/en/api.html#express.router

While creating the router, pass the mergeParams flag.

var router = express.Router({ mergeParams: true })

mergeParams preserves the req.params values from the parent router. If the parent and the child have conflicting param names, the child's value takes precedence.