如何通过 NodeJS 应用程序传递请求查询参数

Question

I'm currently working on learning NodeJs and am running into a problem with passing query parameters. The stack consists of express, request-promise, and mongodb. The design of the application I'm shooting for is to have an express.js that is basically the UI app for users. There is also a server.js that defines any REST api endpoints, and a recipes.js that handles running all the queries and any logic I would want.

Below is the express.js file that I mentioned before that would handle the UI:

// Node imports.
const express = require('express');
const app = express();
const request = require('request');
const rp = require('request-promise');
const url = require('url');

const port = 3001;

// View configuration information.
app.use(express.static('public'));
app.set('view engine', 'ejs');

// Routing.
app.get('/recipes', (req, res) => {
    console.log("TODO(map) In the express.js: " + req.query.count);

    var options = {
    method: 'GET',
    uri: 'http://localhost:3000/recipes',
    json: true
    }

    // Run get and wait on promise before rendering.
    rp(options, (req, res) => {
    }).then((recipes_list) => {
    res.render('index-promise', { pageTitle: 'Recipes', recipes: recipes_list })
    });
})

// Server listening.
app.listen(port, () => {
    console.log('Server listening on http://localhost:' + port);
});

You can see the app has a single URL route for now. The server.js file below shows the API endpoints mentioned above:

// Node imports.
const url = require('url');
const express = require('express');
const app = express();

const port = 3000;

// API imports.
var recipeApi = require('./apis/recipes.js');

// Routing.
app.get('/recipes', (req, res) => {
    console.log("TODO(map) In the server.js: " + req.query.count);
    recipeApi.getRecipesByCount(req, res);
})

// Server listening.
app.listen(port, () => {
    console.log('Server listening on http://localhost:' + port);
});

The final file, recipes.js , connect to the database and gets the data an kicks it back.

// Node imports.
const url = require('url');
const express = require('express');
const app = express();

// Mongo imports.
const MongoClient = require('mongodb').MongoClient;
const Db = require('mongodb').Db
const Server = require('mongodb').Server

// Create a DB object so we can query the db anywhere.
const db = new Db('mydb', new Server('localhost',27017));

/**
 * Function for getting a certain number of recipes.
 * NOTE: The req object should include a "count" query parameter.
 * 
 * req: Request being passed in from the server.js
 * res: Response that will be sent back.
 *
 */
exports.getRecipesByCount = (req, res) =>
{
    console.log("TODO(map) In the recipes.js: " + req.query.count);

    if (!req.query.count)
    {
    req.query.count = 0
    }
    db.open((err, db) => {
    db.collection("recipes").find({}).limit(parseInt(req.query.count)).toArray((err, result) => {
        if (err) throw err;
        res.setHeader('Content-Type', 'application/json');
        res.send(result);
        db.close();
    });
    });

}

So at the end of all this, the issue that I'm running into is in the console.log calls both the server.js and the recipes.js . The req.query.count value is undefined despite the fact that the URL I'm hitting is http://localhost:3000/recipes?count=1 . How am I supposed to pass the information the req object has to the other app (the REST API) so I can get that information to the end point and query the database correctly?

Answer 1

Looks like you're sending a request to the backend API on port 3000 with no query params. In your express.js file you have:

var options = {
method: 'GET',
uri: 'http://localhost:3000/recipes',
json: true
}

Which, as you can see, has NO query parameters. You need to add the params here. If you change this to the code below it should work:

var options = {
method: 'GET',
uri: 'http://localhost:3000/recipes?count=' + req.query.count,
json: true
}