I have been working with a stock api for the past day or two, and I'm trying to make a search engine for it with a filter method. It works, but it can be slow because the initial api fetch response is an array that is about 28,000 indeces. Is there a way to limit the response I get? I looked in the documentation and there doesn't seem to be a solution through the link itself. Any help would be appreciated!
input.addEventListener('keyup', (e) => {
const searchString = e.target.value.toLowerCase();
const filteredCompanies = stockCompanies.filter((company) => {
return (
company.description.toLowerCase().includes(searchString) ||
company.displaySymbol.toLowerCase().includes(searchString)
);
});
displayCompanies(filteredCompanies);
});
const loadCompanies = async () => {
try {
const res = await fetch(`https://finnhub.io/api/v1/stock/symbol?exchange=US&token=${apiKey}`);
stockCompanies = await res.json();
displayCompanies(stockCompanies);
}catch (err) {
console.error(err);
}
};
const displayCompanies = (data) => {
var dynamic = [];
for (var i = 0; i < data.length; i++){
dynamic.push(`
<div class="listings_card">
<h1>${data[i].description}</h1>
<p>${data[i].displaySymbol}</p>
</div>`);
}
document.querySelector('.listings').innerHTML = dynamic.join('');
};
loadCompanies();
If api doesn't support the feature you can not. But you can eliminate the list after you receive the response. Try this way:
const loadCompanies = async () => {
try {
const res = await fetch(`https://finnhub.io/api/v1/stock/symbol?exchange=US&token=${apiKey}`);
const res_data = await res.json();
stockCompanies = res_data.slice(0, 50)
displayCompanies(stockCompanies);
} catch (err) {
console.error(err);
}
};
Related
I write some code to getting info
const stock = await Stock.find({
exchange: exchange
});
// Here stock array length is 5300
stock.forEach(async (stockEl) => {
const EOD_API = process.env.EOD_HISTORICAL_API
const {data} = await axios.get(`https://eodhistoricaldata.com/api/fundamentals/${stockEl.code}?api_token=${EOD_API}&filter=General::Industry`);
console.log(data);
});
Here I place get request for every stock array element by forEach function. Then it give me error like image-
Click to see images
But When I place it outside of forEach function like this-
const EOD_API = process.env.EOD_HISTORICAL_API
const {data} = await axios.get(`https://eodhistoricaldata.com/api/fundamentals/${stockEl.code}?api_token=${EOD_API}&filter=General::Industry`);
console.log(data);
Then it gives no error. For Remembering Stock has 5300 element, that means axios run 5300 times.
Any solution or idea?
You need to make a few changes:
Replace forEach with for because forEach is not promise aware
Use try, catch => catch any errors
Use Promise.allSettled => it allows you to run all promisses together without waiting each other which in return will enhance your app performance. It returns an array with status ("fulfilled", "rejected")
const fetchSingleStockElement = async (stockEl) => {
try {
const EOD_API = process.env.EOD_HISTORICAL_API,
{ data } = await axios(
`https://eodhistoricaldata.com/api/fundamentals/${stockEl.code}?api_token=${EOD_API}&filter=General::Industry`
);
return data;
} catch (err) {
throw new Error(err);
}
};
const fetchAllStockData = async () => {
let promisesArray = [];
try {
//fetch stock array
const { data } = await Stock.find({
exchange: exchange
});
//fetch single stock
for (let i = 0; i < data.length; i++) {
promisesArray.push(fetchSingleStockElement(data[i].id));
}
const results = await Promise.allSettled(promisesArray);
console.log('results', results);
} catch (err) {
console.log('results error', err);
}
};
Here is a working example with fake API of 4466 entries:
const fetchSingleAirline = async (airlineId) => {
try {
const { data } = await axios(`https://api.instantwebtools.net/v1/airlines/${airlineId}`);
return data;
} catch (err) {
throw new Error(err);
}
};
const fetchAllAirlineData = async () => {
let promisesArray = [];
try {
const { data } = await axios('https://api.instantwebtools.net/v1/airlines');
for (let i = 0; i < data.length; i++) {
promisesArray.push(fetchSingleAirline(data[i].id));
}
const results = await Promise.allSettled(promisesArray);
console.log('results', results);
} catch (err) {
console.log('results error', err);
}
};
Doing await in forEach doesn't hold the process since forEach is not promise-aware. Try this instead:
(async () => {
for (let index = 0; index < stock.length; index++) {
const EOD_API = process.env.EOD_HISTORICAL_API
const {data} = await axios.get(`https://eodhistoricaldata.com/api/fundamentals/${stock[i].code}?api_token=${EOD_API}&filter=General::Industry`);
console.log(data);
}
})();
More information.
I can't seem to figure out how to save the results of SomeQuery promise. Essentially I would like to take the value in res and pipe it into parseQuery function and return the final results. How do I make the parsed result accessible to an APIs response.
const neo4j = require('neo4j-driver')
var parser = require('parse-neo4j')
const astria_queries = require('./astriaQueries')
const uri = 'bolt://astria_graph:7687'
const user = 'xxx'
const password = 'xxx'
const someQuery = (query) => {
// run statement in a transaction
const driver = neo4j.driver(uri, neo4j.auth.basic(user, password))
const session = driver.session({ defaultAccessMode: neo4j.session.READ })
const tx = session.beginTransaction()
tx.run(query)
.then((res) => {
// Everything is OK, the transaction will be committed
parseQuery(res)
})
.then(() => {
// Everything is OK, the transaction will be committed
})
.catch((e) => {
// The transaction will be rolled back, now handle the error.
console.log(e)
})
.finally(() => {
session.close()
driver.close()
})
}
const parseQuery = (result) => {
try {
const test = parser.parse(result)
console.log(test)
} catch (err) {
console.log(err)
}
}
module.exports = {
someQuery,
}
It finally clicked with me. Here is the solution I came up with. Hopefully it will help others. If there is a better way please let me know. Thank you #fbiville for you help.
async actions
const neo4j = require('neo4j-driver')
var parser = require('parse-neo4j')
const astria_queries = require('./astriaQueries')
const uri = 'bolt://astria_graph:7687'
const user = 'neo4j'
const password = 'neo'
async function getRecords(query) {
// run statement in a transaction
const driver = neo4j.driver(uri, neo4j.auth.basic(user, password))
const session = driver.session({ defaultAccessMode: neo4j.session.READ })
const tx = session.beginTransaction()
try {
const records = await tx.run(query)
const parseRecords = await parseQuery(records)
return parseRecords
} catch (error) {
console.log(error)
} finally {
session.close()
driver.close()
}
}
async function parseQuery(result) {
try {
const parsedRes = await parser.parse(result)
// console.log(parsedRes)
return parsedRes
} catch (err) {
console.log(err)
}
}
// getRecords(astria_queries.get_data_sources)
module.exports = {
getRecords,
}
api send()
exports.get_data_sources = async (req, res) => {
try {
queryFuns.getRecords(astria_queries.get_data_sources).then((response) => {
res.send(response)
})
} catch (error) {
res.status(500).send(error)
console.log(error)
}
}
I'm working with a really big array in JS and I can see most of the time is used for loading and parsing the json data.
// is a Chrome Extension (but maybe I can move it to a nodejs app)
This is basically how I loading my data:
async function loadData(jsonFiles){
const fullData = [];
for(const jsonFile of jsonFiles){
const localUrl = 'http://localhost/'+jsonFile;
const response = await fetch(jsonFile);
if ( response.ok ){
try{
const data = await response.json();
const L = data.length;
for (let k = 0; k < L; k++) {
fullData.push(data[k]);
}
}
catch(e){
}
}
}
return fullData;
}
Is there any faster way to do that? even if it implies to save the data in another way/format
You can do the fetch calls in parallel, but other than that there's not a lot more you can do:
function loadData(jsonFiles){
return Promise.all(
jsonFiles.map(async file => {
const localUrl = 'http://localhost/'+jsonFile;
const response = await fetch(jsonFile);
if (response.ok) {
try{
return await response.json();
} catch (e) {
return null;
}
} else {
return null;
}
})
).then(results => {
return results.filter(result => result); // Filter out the `null`s
}).then(results => {
return results.flat(); // Flatten the results into one array
});
}
Make call and transform to json parallel
async function loadData(jsonFiles){
const calls = [];
for(const jsonFile of jsonFiles){
calls.push(fetch(jsonFile).then(response => response.json()));
}
return await Promise.allSettled(calls)
.then(parts => parts.filter(({status}) => status === "fulfilled"))
.then(parts => parts.map(({value}) => value))
.then(parts => parts.flat());
}
I know that old school for loop works in the traditional way - that it waits for the await to finish getting results.
But in my use case, I need to read a file from local/s3 and process it line by line, and for each line I need to call an External API.
Generally I use await inside the loop because all are running inside a lambda and I don't want to use all memory for running it parallelly.
Here I am reading the file using a stream.on() method, and in order to use await inside that, I need to add async in read method, like so:
stream.on('data',async () =>{
while(data=stream.read()!==null){
console.log('line');
const requests = getRequests(); // sync code,no pblms
for(let i=0;i<requests.length;i++){
const result = await apiCall(request[i);
console.log('result from api')
const finalResult = await anotherapiCall(result.data);
}
}
});
This is working but order in which the lines are processed is not guaranteed. I need all in a sync manner. Any help?
Complete Code
async function processSOIFileLocal (options, params) {
console.log('Process SOI file');
const readStream = byline.createStream(fs.createReadStream(key));
readStream.setEncoding('utf8');
const pattern = /^UHL\s|^UTL\s/;
const regExp = new RegExp(pattern);
readStream.on('readable', () => {
let line;
while (null !== (line = readStream.read())) {
if (!regExp.test(line.toString())) {
totalRecordsCount++;
dataObject = soiParser(line);
const { id } = dataObject;
const XMLRequests = createLoSTRequestXML(
options,
{ mapping: event.mapping, row: dataObject }
);
console.log('Read line');
console.log(id);
try {
for (let i = 0;i < XMLRequests.length;i++) {
totalRequestsCount++;
console.log('Sending request');
const response = await sendLoSTRequest(
options,
{ data: XMLRequests[i],
url: LOST_URL }
);
console.log("got response");
const responseObj = await xml2js.
parseStringPromise(response.data);
if (Object.keys(responseObj).indexOf('errors') !== -1) {
fs.writeFileSync(`${ERR_DIR}/${generateKey()}-${id}.xml`, response.data);
failedRequestsCount++;
} else {
successRequestsCount++;
console.log('Response from the Lost Server');
console.log(response[i].data);
}
}
} catch (err) {
console.log(err);
}
}
}
})
.on('end', () => {
console.log('file processed');
console.log(`
************************************************
Total Records Processed:${totalRecordsCount}
Total Requests Sent: ${totalRequestsCount}
Success Requests: ${successRequestsCount}
Failed Requests: ${failedRequestsCount}
************************************************
`);
});
}
async function sendLoSTRequest (options, params) {
const { axios } = options;
const { url, data } = params;
if (url) {
return axios.post(url, data);
// eslint-disable-next-line no-else-return
} else {
console.log('URL is not found');
return null;
}
}
Code needs to flow like so:
read a line in a sync way
process the line and transform the line into an array of two members
for every member call API and do stuff
once line is complete, look for another line, all done in order
UPDATE: Got a workaround..but it fires stream.end() without waiting stream to finish read
async function processSOIFileLocal (options, params) {
console.log('Process SOI file');
const { ERR_DIR, fs, xml2js, LOST_URL, byline, event } = options;
const { key } = params;
const responseObject = {};
let totalRecordsCount = 0;
let totalRequestsCount = 0;
let failedRequestsCount = 0;
let successRequestsCount = 0;
let dataObject = {};
const queue = (() => {
let q = Promise.resolve();
return fn => (q = q.then(fn));
})();
const readStream = byline.createStream(fs.createReadStream(key));
readStream.setEncoding('utf8');
const pattern = /^UHL\s|^UTL\s/;
const regExp = new RegExp(pattern);
readStream.on('readable', () => {
let line;
while (null !== (line = readStream.read())) {
if (!regExp.test(line.toString())) {
totalRecordsCount++;
dataObject = soiParser(line);
const { id } = dataObject;
const XMLRequests = createLoSTRequestXML(
options,
{ mapping: event.mapping, row: dataObject }
);
// eslint-disable-next-line no-loop-func
queue(async () => {
try {
for (let i = 0;i < XMLRequests.length;i++) {
console.log('Sending request');
console.log(id);
totalRequestsCount++;
const response = await sendLoSTRequest(
options,
{ data: XMLRequests[i],
url: LOST_URL }
);
console.log('got response');
const responseObj = await xml2js.
parseStringPromise(response.data);
if (Object.keys(responseObj).indexOf('errors') !== -1) {
// console.log('Response have the error:');
// await handleError(options, { err: responseObj, id });
failedRequestsCount++;
fs.writeFileSync(`${ERR_DIR}/${generateKey()}-${id}.xml`, response.data);
} else {
console.log('Response from the Lost Server');
console.log(response[i].data);
successRequestsCount++;
}
}
} catch (err) {
console.log(err);
}
});
}
}
})
.on('end', () => {
console.log('file processed');
console.log(`
************************************************
Total Records Processed:${totalRecordsCount}
Total Requests Sent: ${totalRequestsCount}
Success Requests: ${successRequestsCount}
Failed Requests: ${failedRequestsCount}
************************************************
`);
Object.assign(responseObject, {
failedRequestsCount,
successRequestsCount,
totalRecordsCount,
totalRequestsCount
});
});
}
Thank You
The sample code at the top of your question could be rewritten like
const queue = (() => {
let q = Promise.resolve();
return (fn) => (q = q.then(fn));
})();
stream.on('data', async() => {
while (data = stream.read() !== null) {
console.log('line');
const requests = getRequests(); // sync code,no pblms
queue(async () => {
for (let i = 0; i < requests.length; i++) {
const result = await apiCall(request[i]);
console.log('result from api');
const finalResult = await anotherapiCall(result.data);
}
});
}
});
Hopefully that will be useful for the complete code
If anyone want a solution for synchronisely process the file, ie, linebyline read and execute some Async call, it's recommended to use inbuilt stream transform. There we can create a transform function and return a callback when finishes.
That's will help of any one face this issues.
Through2 is a small npm library that also can be used for the same.
I have this request handler on my node server. It has three MongoDB queries, and I want all the results to be returned, before the response is sent.
api.get('/getStats/:productID', (req,res)=>{
let data = {};
let dailySales = [];
let avgProduct = "";
let customers = [];
Sales.find({productID: productID}).then(
sales => {
dailySales = sales;
}
);
Products.find({}).then(
products => {
// Calculate Avg product here
avgProduct = result;
}
);
Customers.find({}).then(
customers => {
customers = customers;
}
);
data = {
dailySales,
avgProduct,
customers
};
res.json(data);
});
But running this returns
data: {
dailySales: [],
avgProduct: "",
customers: []
}
i.e. The Mongo response is returning before the data is run. Please how to I fix. Thank You
wait for all the promises to resolve before sending the actual response
const sales = Sales.find({productID: productID});
const allProducts = Products.find({});
const allCustomers = Customers.find({});
Promise.all([sales, allProducts, allCustomers])
.then(data => res.json(data));
you can try using the Promise.all where you can pass the MongoDB queries as parameter to it ,the promise will be resolved when all the queries return the result in the array
Try using the in-built util.promisify function along with
async-await to get data correctly!
const promisify = require('utils').promisify;
const salesFindOnePromise = promisify(Sales.find);
const productsFindAllPromise = promisify(Products.find);
const customersFindAllPromise = promisify(Customers.find);
findDailySalesByIdAsync = async (productID) => {
try {
return await salesFindOnePromise({ productID: productID });
} catch(err) {
throw new Error('Could not fetch the appropriate sales with productID');
}
}
findProductsAsync = async () => {
try {
return await productsFindAllPromise({});
} catch (err) {
throw new Error('Could not fetch sales!');
}
}
findCustomersAsync = async () => {
try {
return await customersFindAllPromise({});
} catch (err) {
throw new Error('Could not fetch customers!');
}
}
api.get('/getStats/:productID', async (req,res)=>{
try {
const dailySales = await findDailySalesByIdAsync(productID);
const avgProduct = await findProductsAsync();
const customers = await findCustomersAsync();
const data = {
dailySales,
avgProduct,
customers
};
return res.status(200).send(data);
} catch(err) {
console.err(`Failed because: {err}`);
throw new Error('Could not fetch data because of some error!');
}
});