CODEWITHSUNDEEP
javascriptnode.jspromise
ChrisY
ChrisY

Reputation: 3

Writing file with promises return [object Promise]

I am writing a scraper in nodejs with Axios which is intended to access a list of urls and then save it to file with fs. However fs writes [object Promise] to the file instead of the intended html response. Here is the code:


var urls = [url1, url2, url3]
var responses = [];
var completed_requests = 0;
for (i in urls) {

    responses.push(axios.get(urls[i]))
    completed_requests ++

    if(completed_requests == urls.length){

    Promise.all(responses).then((e)=>{
        for (i in e) {
            console.log(responses[i]) //this returns the http correctly
            return fs.writeFile('/answer/'+ i +'.txt', responses[i], function(err) {
                if(err) {
                    return console.log(err);
                }})
        }

    }
    )}
}

Upvotes: 0

Views: 1735

Answers (2)

Aviso
Aviso

Reputation: 695

It is writing '[object promise]' because you are writing promise object to the file and also don't return value from for loop if you do so it will run only once . If you want write only html then following code will work.

var urls = [url1,url2,url3]
var responses = [];
var completed_requests = 0;
for (i in urls) {
    responses.push(axios.get(urls[i]))
    completed_requests ++

    if(completed_requests == urls.length){
        console.log('here');

    Promise.all(responses).then((e)=>{

        for (i in e) {
             fs.writeFile( i +'.txt',  e[i].data, function(err) {
                if(err) {

                     console.log(err);
                }})
        }

    }
    )}
}

If you want to write whole object use JSON.stringify(e[i]) .

Upvotes: 1

iwaduarte
iwaduarte

Reputation: 1698

I think you have first to fill the array so you code is working unexpected just because of a curly brace and because your are saving the Promise object instead the response payload. Please note the comments:

var urls = [url1, url2, url3]
var responses = [];
//var completed requests not needed as a flag here
for (i in urls) {
    responses.push(axios.get(urls[i]))

}

//then after having an array of Promises you should then wait for them
//also you should be saving the `e` variable instead of the responses (array) that is a promise.

Promise.all(responses).then((e)=>{
    for (i in e) {
        console.log(responses[i]) //this returns the http correctly
        return fs.writeFile('/answer/'+ i +'.txt', e, function(err) {
            if(err) {
                return console.log(err);
            }})
    }

}
)}

Upvotes: 0

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