I'm using node.js.
I've managed to load and parse my .json file using async.
The whole concept is very new to me, I can see my .json data in console but I'm not really sure how to actually use my data now,..
async function getJsonFile() {
let response = await fetch('example.json');
let responsejson = await response.json();
let str = JSON.stringify(responsejson);
let jsonData = JSON.parse(str);
return jsonData;
};
getJsonFile().then(console.log); // I see my .json file in console, how can I use it ?
}
I think that's the way to do it:
var json = await getJsonData();
// use it
If you are trying to use your data which is inside your json you can do this :
// Use this in an async function
const data = await getJsonFile();
// Then get value of one key
console.log(data.key); // from {key: "value"}, you'll get value
To actually use what is in the JSON you need to store it as a variable and then access it in ways that are useful to you. You can access properties of objects using property accessors.
// Save as variable
var json = await getJsonData();
// Do something with properties of data
console.log(json['key']);
Related
const df = require("durable-functions");
module.exports = async function (context, req) {
const client = df.getClient(context);
context.log(`Function Name = '${req.params.functionName}'.`);
context.log(`Body = '${req.body}'.`);
const instanceId = await client.startNew(req.params.functionName, undefined, req.body);
context.log(`Started orchestration with ID = '${instanceId}'.`);
return client.createCheckStatusResponse(context.bindingData.req, instanceId);
};
I have tried to use POSTMAN or https://reqbin.com/ for testing but I always get object.
It is a simple case but I don't understand why it is not JSON object.
I read this one
TypeScript Azure Function Read Body of POST method as JSON
but it didn't help me.
Everything is fine!
It is already deserialized json object.
It looks like the normal string in a log after
JSON.stringify(req.body)
My fault was that I wrongly got it in the orchestrator function from the context.
I am working on building a blog API for a practice project, but am using the data from an external API. (There is no authorization required, I am using the JSON data at permission of the developer)
The idea is that the user can enter multiple topic parameters into my API. Then, I make individual requests to the external API for the requested info.
For each topic query, I would like to:
Get the appropriate data from the external API based on the params entered (using a GET request to the URL)
Add the response data to my own array that will be displayed at the end.
Check if each object already exists in the array (to avoid duplicates).
res.send the array.
My main problem I think has to do with understanding the scope and also promises in Axios. I have tried to read up on the concept of promise based requests but I can't seem to understand how to apply this to my code.
I know my code is an overall mess, but if anybody could explain how I can extract the data from the Axios function, I think it could help me get the ball rolling again.
Sorry if this is a super low-level or obvious question - I am self-taught and am still very much a newbie!~ (my code is a pretty big mess right now haha)
Here is a screenshot of the bit of code I need to fix:
router.get('/:tagQuery', function(req, res){
const tagString = req.params.tagQuery;
const tagArray = tagString.split(',');
router.get('/:tag', function(req, res){
const tagString = req.params.tag;
const tagArray = queryString.split(',');
const displayPosts = tagArray.map(function(topic){
const baseUrl = "https://info.io/api/blog/posts";
return axios
.get(baseUrl, {
params: {
tag: tag
}
})
.then(function(response) {
const responseData = response.data.posts;
if (tag === (tagArray[0])){
const responseData = response.data.posts;
displayPosts.push(responseData);
} else {
responseData.forEach(function(post){
// I will write function to check if post already exists in responseData array. Else, add to array
}); // End if/then
})
.catch(function(err) {
console.log(err.message);
}); // End Axios
}); // End Map Function
res.send(displayPosts);
});
Node.js is a single thread non-blocking, and according to your code you will respond with the result before you fetching the data.
you are using .map which will fetch n queries.
use Promise.all to fetch all the requests || Promise.allsettled.
after that inside the .then of Promise.all || promise.allsettled, map your result.
after that respond with the mapped data to the user
router.get('/:tag', function (req, res) {
const tagString = req.params.tag;
const tagArray = queryString.split(',');
const baseUrl = "https://info.io/api/blog/posts";
const topicsPromises=tagArray.map((tobic)=>{
return axios
.get(baseUrl, {
params: {
tag: tag
}
})
});
Promise.all(topicsPromises).then(topicsArr=>{
//all the data have been fetched successfully
// loop through the array and handle your business logic for each topic
//send the required data to the user using res.send()
}).catch(err=>{
// error while fetching the data
});
});
your code will be something like this.
note: read first in promise.all and how it is working.
Is there any way to convert res object in nodejs to JSON object
app.post('/validateUser', function (req, res)
{
console.log('in post validateUser');
var usr = req.body.usr;
var pwd = req.body.pwd;
//like this
callSomeFunctionOrWebservice(JSON.stringify({data:req.body, respVar:res}));
// the above function gave me error //TypeError: Converting circular structure to JSON at
});
what I need is to convert the entire thing to JSON, pass the arguments and retrieve the arguments on the other function maybe call a web service
I checked out flatted, but I don't know how to encode with flatted
I tried this
var flt = require('flatted');
//JSON encrypt
flt.stringify({data:req.body, respVar:res});
//JSON parse
flt.parse(varData);
But I couldn't get it to work. Can someone helps me or point me in the correct direction?
You no need convert res to json it is already in json object only.
So
var new_object = {data:req.body, respVar:res}
or if you want combine both
var new_object = {...req.body,...res}
console.log(new_object)
Check that it can accessible like json only
I need to write a lambda function and send a number in the api request field to genrate the number of QR codes and store them in a S3 bucket.I am using the serverless framework with the aws-nodejs template.
To describe the task briefly lets say I get a number input in the api request PathParameters and based on these number I have to generate those number of QR's using the qr npm package and then store these generated qr's in the s3 bucket
this is what i have been able to do so far.
module.exports.CreateQR = (event,context) =>{
const numberOfQR = JSON.parse(event.pathParameters.number) ;
for(let i=0;i<numberOfQR;i++){
var d= new Date();
async function createQr(){
let unique, cipher, raw, qrbase64;
unique = randomize('0', 16);
cipher = key.encrypt(unique);
raw = { 'version': '1.0', data: cipher, type: 'EC_LOAD'}
// linkArray.forEach( async (element,index) =>{
let qrcode = await qr.toDataURL(JSON.stringify(raw));
console.log(qrcode);
// fs.writeFileSync('./qr.html', `<img src="${qrcode}">`)
const params = {
Bucket:BUCKET_NAME,
Key:`QR/${d}/img${i+1}.jpg`,
Body: qrcode
};
s3.upload(params , function(err,data){
if(err){
throw err
}
console.log(`File uploaded Successfully .${data.Location}`);
});
}
createQr();
}
};
I have been able to upload a given number of images to the bucket but the issue i am facing is the images are not going in the order.I think the problem is with the asynchronous code. Any idea how to solve this issue
that's because you're not awaiting the s3 to upload, but instead you have a callback.
you should use the .promise of s3 and then await it, so you'll wait the file to be uploaded before move to the next one
I changed the example of code
See docs:
https://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/S3.html#upload-property
https://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/S3/ManagedUpload.html#promise-property
// see the async keyword before the lambda function
// we need it for use the await keyword and wait for a task to complete before continue
module.exports.CreateQR = async (event,context) =>{
const numberOfQR = JSON.parse(event.pathParameters.number) ;
// moved your function out of the loop
function createQr(){
// ...
// here we call .promise and return it so we get a Task back from s3
return s3.upload(params).promise();
}
for(let i=0;i<numberOfQR;i++){
// ....
// here we await for the task, so you will get the images being created and uploaded in order
await createQr();
}
};
hope it guide you towards a solution.
I have a simple HTTPS request -
https://api.pro.coinbase.com/products/btc-eur/ticker
In the browser this returns one object. What's the simplest code that will allow me to retrieve and display this object (as is) in the terminal of Node?
const https = require('https')
const url = https.get('https://api.pro.coinbase.com/products/btc-eur/ticker')
const myObject = JSON.parse(url)
console.log(myObject)
A simple copy / paste of the above code in VSC returns the error SyntaxError: Unexpected token o in JSON at position 1.
#mamba76, welcome to the SO community. Please use Node.js node-fetch package. It is much simpler to use. You can install it using npm install.
Following code might help:
"use strict";
const fetch = require('node-fetch')
async function getValue() {
// Invoke the API.
// Wait until data is fetched.
let response = await fetch('https://api.pro.coinbase.com/products/btc-eur/ticker');
let value = await response.json();
return value;
}
getValue().then(result => {console.log(result.price);});
As a good practice, always assume that API calls over the HTTP (whether in your own network or outside) might take time to return data and hence you should use async-await pattern to make these requests.
Extending #Akshay.N's answer and without using external dependencies,
const https = require('https')
https.get("https://api.pro.coinbase.com/products/btc-eur/ticker",res=>{
let body = '';
res.on('data', (chunk) => { body += chunk; });
res.on('end', () => {
const myObject = JSON.parse(body);
console.log(myObject);
})
})
Now, what we're doing here is waiting on the data event as long as the data is coming in, and appending it to the variable body. Once the end event is encountered, we take that as a signal that all data has been received and we can proceed to parse the body into an object using JSON.parse (assuming the data was serialized in JSON; if it wasn't JSON.parse will throw an error).
This tutorial is helpful: https://davidwalsh.name/nodejs-http-request
try something like this:-
https.get("https://api.pro.coinbase.com/products/btc-eur/ticker",res=>{
res.on('data', (chunk) => { console.log(JSON.parse(chunk))})
})
With node (you need request module) :
// display object
(require("request")).get({
url: "myurl",
json: true
}, function(e,r,b){
console.log(b);
});
// display as string
(require("request")).get({
url: "myurl",
json: false
}, function(e,r,b){
console.log(b);
});
With just curl in your terminal (without node)
curl myurl