CODEWITHSUNDEEP
node.jsasynchronousasync.jscheerio
Mattyx Drink -Drink-
Mattyx Drink -Drink-

Reputation: 63

Async function called in a async function Node.Js

i'm new with Node.Js. I want to make a function call in another function and when everything is finished, print a file.

But the functions are asynchronous so when the first ends node print the file without waiting the second one..

I tried the waterfall method of Async library but is not the waterfall that i need.. Async is a big library with a lots of different patterns, maybe one of these are the solution

This is the code:

request(url, function (error, response, html) {

    var json_list = [];

    if (!error) {
        var $ = cheerio.load(html);

        $('.fixed-recipe-card').each(function () {

            var json = {title: "", description: "", rating: "", ingredients: [], url: ""};

            json.title = $(this).children().last().children().first().text().trim();
            json.description = $(this).children().last().children().first().next().children().last().text().trim();
            json.rating = $(this).children().last().children().first().next().children().first().children().first().attr('data-ratingstars');
            json.url = $(this).children().last().children().first().next().attr('href');

            request(json.url, function (error, response, html) {
                var $ = cheerio.load(html);
                $('.checkList__line').filter(function () {
                    var ingredient = $(this).children().first().children().last().text().trim();
                    if (ingredient !== "Add all ingredients to list") {
                        console.log(ingredient);
                        json.ingredients.push(ingredient);
                    }
                });
            });


            json_list.push(json);

        });
    }

    fs.writeFile('output.json', JSON.stringify(json_list, null, 4), function (err) {
        console.log('success');
    })

    res.send(JSON.stringify(json_list));
});

Upvotes: 2

Views: 100

Answers (1)

Martín Zaragoza
Martín Zaragoza

Reputation: 1817

You could use Promises:

let promises = [];

$('.fixed-recipe-card').each(function () {

    var json = {title: "", description: "", rating: "", ingredients: [], url: ""};

    json.title = $(this).children().last().children().first().text().trim();
    json.description = $(this).children().last().children().first().next().children().last().text().trim();
    json.rating = $(this).children().last().children().first().next().children().first().children().first().attr('data-ratingstars');
    json.url = $(this).children().last().children().first().next().attr('href');

    let p = new Promise(function(resolve, reject) {
        request(json.url, function (error, response, html) {
            if(error) { reject(error); } // reject promise on error

            var $ = cheerio.load(html);
            $('.checkList__line').filter(function () {
                var ingredient = $(this).children().first().children().last().text().trim();
                if (ingredient !== "Add all ingredients to list") {
                    console.log(ingredient);
                    json.ingredients.push(ingredient);
                }
            });

            resolve(response); // promise success
        });
    });
    promises.push(p);

});

Promise.all(promises).then(function(values) {
    console.log(values);
    fs.writeFile('output.json', JSON.stringify(json_list, null, 4), function (err) {
        console.log('success');
    })
    ...
});
...

With Promise.all you can execute something when all async calls (built as promises) have been resolved

Check this link: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise/all

Hope this helps

Upvotes: 1

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