Facing an issue about populating the javascript array

Question

I have been working on a project which is to create a node.js server and I have to read some text from the file. Then I want to use a Python API to consume these text and get the result back. I have been able to hit these API and get the response successfully.

What have I done till now - 1. Created a node server
2. read all the file and get the text content from them
3. create a flask server with appropriate api
4. hit these API to get the response

app.js

var bodyParser = require('body-parser');
var request = require('request-promise');

var app = express();

app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: false }));

app.get('/', function(req, res){
    res.send('Node server')
})

app.get('/postdatatoFlask', function (req, res) {
    var fs = require('fs');
    categories = ['business', 'entertainment']

    // answers SHOULD CONTAIN ALL THE RESPONSES FROM THE FLASK API
    var answers = []

    //iterating over different file 
    categories.forEach(function(category){

        for(var i=100;i<=100;i++){

            //creating the path for the new file to be read 
            var path = 'dataset/'+category+'/'+i.toString()+'.txt';

            //textContent contains the data read from file 
            var textContent = fs.readFileSync(path, 'utf8')

            //creating the object 
            var data = { content : textContent }

            //posting the data to the flask server on route postdata
            var options = {
                method: 'POST',
                uri: 'http://127.0.0.1:5000/postdata',
                body: data,
                json: true 
            };

            // returndata is the variable contains the data return by flask API
            var returndata
            var sendrequest = request(options)
            .then(function (parsedBody) {
                 // parsedBody contains the data sent back from the Flask server
                returndata = parsedBody;
                answers.push(returndata)
                console.log(returndata) // do something with this data, here I'm assigning it to a variable.
            })
            .catch(function (err) {
                console.log(err);
            });
        }
    })


    console.log('Showing the responses!!!')
    console.log(answers)
    console.log('Stoping the showcase!!!!')

    res.send('done');
});

app.listen(3000);

compute.py

import json
import time
from pdfminer.pdfinterp import PDFResourceManager, PDFPageInterpreter
from pdfminer.converter import TextConverter
from pdfminer.layout import LAParams
from pdfminer.pdfpage import PDFPage
from io import StringIO
from sklearn.feature_extraction.text import TfidfVectorizer
from sklearn.metrics.pairwise import cosine_similarity
import numpy as np
import pandas as pd

app = Flask(__name__)

@app.route('/')
def index():
    return "Flask server"

@app.route('/postdata', methods = ['POST'])
def postdata():
    data = request.get_json()
    # print(data['content'])
    textContent = data['content']
    print(textContent)
    print('-- --- -- --- -- -- -- -- -- --')
    return json.dumps({"newdata":textContent})

if __name__ == "__main__":
    app.run(port=5000)

Problem
1. In app.js I want to store all the responses in answer array but I am unable to populate it.
2. why output from console.log(returndata) print after console.log(answer)

for(var i=100;i<=100;i++), is there a typing mistake in this part? — Ajay Dabas
– Ajay Dabas, Commented Jan 21, 2020 at 14:15
Why would you want to run a loop just for 1 iteration(i=100 and then loop terminates)? Why not remove the loop if it serves no purpose? — Ajay Dabas
– Ajay Dabas, Commented Jan 21, 2020 at 14:20

D. H Luong · Accepted Answer · 2020-01-21 14:56:27Z

1

With answers.push(returndata), you are pushing an array inside another array. If you want to concat the content of returndata to answers, use answers.push(...returndata)
Javascript has an async, non blocking IO runtime, so here:

var sendrequest = request(options)
            .then(function (parsedBody) {
                 // parsedBody contains the data sent back from the Flask server
                returndata = parsedBody;
                answers.push(returndata)
                console.log(returndata) // do something with this data, here I'm assigning it to a variable.
            })

The callback inside then is put to the callstack after those:

console.log('Showing the responses!!!')
    console.log(answers)
    console.log('Stoping the showcase!!!!')

answered Jan 21, 2020 at 14:56

D. H Luong

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Comments

Abhishek Patel · Accepted Answer · 2020-01-22 09:34:27Z

0

var options = {
    method: 'POST',
    uri: 'http://127.0.0.1:5000/postdata',
    body: data,
    json: true 
};

// returndata is the variable contains the data return by flask API
try {
    // temp.push(await request(options));
    answers.push(await request(options));
    } catch(err) {
    throw err;
}

answered Jan 22, 2020 at 9:34

Abhishek Patel

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