I have a block of code that calls an Api and saves results if there are differences or not. I would like to return different values for DATA as layed out on the code. But this is obviously not working since Its returning undefined.
let compare = (term) => {
let DATA;
//declare empty array where we will push every thinkpad computer for sale.
let arrayToStore = [];
//declare page variable, that will be the amount of pages based on the primary results
let pages;
//this is the Initial get request to calculate amount of iterations depending on result quantities.
axios.get('https://api.mercadolibre.com/sites/MLA/search?q='+ term +'&condition=used&category=MLA1652&offset=' + 0)
.then(function (response) {
//begin calculation of pages
let amount = response.data.paging.primary_results;
//since we only care about the primary results, this is fine. Since there are 50 items per page, we divide
//amount by 50, and round it up, since the last page can contain less than 50 items
pages = Math.ceil(amount / 50);
//here we begin the for loop.
for(i = 0; i < pages; i++) {
// So for each page we will do an axios request in order to get results
//Since each page is 50 as offset, then i should be multiplied by 50.
axios.get('https://api.mercadolibre.com/sites/MLA/search?q='+ term +'&condition=used&category=MLA1652&offset=' + i * 50)
.then((response) => {
const cleanUp = response.data.results.map((result) => {
let image = result.thumbnail.replace("I.jpg", "O.jpg");
return importante = {
id: result.id,
title: result.title,
price: result.price,
link: result.permalink,
image: image,
state: result.address.state_name,
city: result.address.city_name
}
});
arrayToStore.push(cleanUp);
console.log(pages, i)
if (i === pages) {
let path = ('./compare/yesterday-' + term +'.json');
if (fs.existsSync(path)) {
console.log("Loop Finished. Reading data from Yesterday")
fs.readFile('./compare/yesterday-' + term +'.json', (err, data) => {
if (err) throw err;
let rawDataFromYesterday = JSON.parse(data);
// test
//first convert both items to check to JSON strings in order to check them.
if(JSON.stringify(rawDataFromYesterday) !== JSON.stringify(arrayToStore)) {
//Then Check difference using id, otherwise it did not work. Using lodash to help.
let difference = _.differenceBy(arrayToStore[0], rawDataFromYesterday[0],'id');
fs.writeFileSync('./compare/New'+ term + '.json', JSON.stringify(difference));
//if they are different save the new file.
//Then send it via mail
console.log("different entries, wrote difference to JSON");
let newMail = mail(difference, term);
fs.writeFileSync('./compare/yesterday-' + term +'.json', JSON.stringify(arrayToStore));
DATA = {
content: difference,
message: "These were the differences, items could be new or deleted.",
info: "an email was sent, details are the following:"
}
return DATA;
} else {
console.log("no new entries, cleaning up JSON");
fs.writeFileSync('./compare/New'+ term + '.json', []);
DATA = {
content: null,
message: "There were no difference from last consultation",
info: "The file" + './compare/New'+ term + '.json' + ' was cleaned'
}
return DATA;
}
});
} else {
console.error("error");
console.log("file did not exist, writing new file");
fs.writeFileSync('./compare/yesterday-' + term +'.json', JSON.stringify(arrayToStore));
DATA = {
content: arrayToStore,
message: "There were no registries of the consultation",
info: "Writing new file to ' " + path + "'"
}
return DATA;
}
}
})
}
}).catch(err => console.log(err));
}
module.exports = compare
So I export this compare function, which I call on my app.js. What I want is to make this compare function return the DATA object, so I can display the actual messages on the front end,
My hopes would be, putting this compare(term) function inside a route in app.js like so:
app.get("/api/compare/:term", (req, res) => {
let {term} = req.params
let data = compare(term);
res.send(data);
})
But as I said, Its returning undefined. I tried with async await, or returning the whole axios first axios call, but Im always returning undefined.
Thank you
