I'm experiencing a strange problem with meteor. I'm trying to make HTTP call an use the data in a React-Component. But I can't access the returned data.
on the server:
'get': function get() {
try {
const data = Meteor.http.get('url', {
params: {
"api_key": "key",
"attribute": "attribute"
}
}
return data.data;
} catch (exception) {
throw new Meteor.Error('500', exception);
}
},
on the client: i've set up a container using withTracker() so that i can access the http response as props in my react component.
export default withTracker(() => {
var data = [];
Meteor.call('get', function(error, success) {
if (error) {
console.log('error', error.reason);
}
if (success) {
data.push(success);
console.log('success', success);
}
});
return {
data,
};
})(Component);
I've tried all possible combination. Using arrays and objects, but none of them worked out. When using console.log(data), I get some data on the client. But using console.log(data[0]) return undefined.
I've also tried returning an object from the server 'get' method. An using js Object.assign. But when calling console.log(data.name) for example, I get undefined on the client.
Maybe I'm not solving it the right way, but I don't understand why this is always returning undefined when I tried to access the object's data.
Solved by calling putting Meteor.call in a component method, and passing another component method in the callback because Meteor.call does not support promises or async / await. reference
Related
I have a Flutter app and I'm trying to get a client nonce from braintree. Per the braintree documentation, I have this in my cloud function:
exports.getClientNonce = functions.https.onCall(async (data, context) => {
gateway.clientToken.generate({}, function (err, response) {
if (err) {
throw new functions.https.HttpsError('unknown', 'Error getting client nonce');
} else {
console.log(`token: ${response.clientToken}`);
return response.clientToken;
}
});
});
Then, in my Flutter app I call the function (again, I'm following what the plugin says):
try {
HttpsCallable callable = CloudFunctions.instance.getHttpsCallable(
functionName: 'getClientNonce',
);
dynamic result = await callable.call({});
final value = result.data;
debugPrint('token: $value');
var data = await BraintreePayment().showDropIn(
nonce: value,
amount: '2.0',
enableGooglePay: false,
inSandbox: true);
print("Response of the payment $data");
} on CloudFunctionsException catch (e) {
debugPrint('An error occurred');
} catch (e) {
debugPrint('An error occurred');
}
}
I tried changing the cloud function so that it only returns a random number (as soon as the function is executed), and my Flutter app is correctly receiving the value (so the cloud function is communicating fine). And in my Firebase console, I am able to view the client nonce specified by console.log. But the function is for whatever reason unable to return the actual client nonce. (It should be should be some string hash that is >2000 characters long)
The callable function needs to return a promise from the top-level of the function callback that resolves with the value to return. Right now, you're returning nothing from the top-level. The return you have now is just returning a value from the inner callback function that you pass to braintree API. This isn't going to propagate to the top level.
What you need to do is either use a version of braintree API that returns an API (if one exists), or promisify the existing call that uses a callback.
See also "3. Node style callback" here: How do I convert an existing callback API to promises?
I have not tested this, but the general format if you apply that pattern will look more like this:
exports.getClientNonce = functions.https.onCall(async (data, context) => {
return new Promise((resolve, reject) => {
gateway.clientToken.generate({}, function (err, response) {
if (err) {
reject(new functions.https.HttpsError('unknown', 'Error getting client nonce'));
} else {
console.log(`token: ${response.clientToken}`);
resolve(response.clientToken);
}
});
});
});
I'm trying to build a backend webhook for the Google Assistant that reads records from DynamoDB.
This is my code:
// Handle the Dialogflow intent named 'trip name'.
// The intent collects a parameter named 'tripName'.
app.intent('trip name', (conv, {tripName}) => {
const dynamoDb = IS_OFFLINE === true ?
new AWS.DynamoDB.DocumentClient({
region: 'ap-south-1',
// endpoint: 'http://127.0.0.1:8080',
}) :
new AWS.DynamoDB.DocumentClient({
region: 'ap-south-1',
// endpoint: 'http://127.0.0.1:8080',
});
const params = {
TableName: ACTIVITIES_TABLE
Key: {
'name':tripName
}
};
// conv.close('error retrieving!'); THIS WORKS
dynamoDb.get(params, (error, result) => {
// conv.close('error retrieving!'); THIS DOES NOT
if (error) {
conv.close('error retrieving!');
}
else {
conv.close(JSON.stringify(result, null, 2));
}
});
});
If I were to use conv from outside the DynamoDB function it works, but from inside it does not and return this error:
2019-08-03T03:56:22.521Z ** ERROR Error: No response has been set. Is this being used in an async call that was
not returned as a promise to the intent handler?
It made me conclude that maybe I'm not allowed to access an arrow function argument from another nested arrow function?
I'm using Actions on Google Client Library.
The problem has nothing to do with accessing parameters from one arrow function in another - that is perfectly allowed.
The issue is, as the error message suggests, that you are using an asynchronous function (a function that requires a callback0, but not returning a Promise object. The actions-on-google library requires you to return a Promise from your Intent Handler if you're doing any asynchronous operations so it knows to wait for those operations to complete.
You'll need to switch from using a callback in your call to dynamoDb.get() to using a Promise instead. To do this, you need to not include the callback function, so get() returns an AWS.Request object. This object has a promise() method, so you would use this to return the results from the Promise and then() chain. (And you must return this Promise.)
In your case, it might look something like this
return dynamoDb.get(params).promise()
.then( result => {
conv.close(JSON.stringify(result, null, 2));
})
.catch( error => {
conv.close('error retrieving!');
});
This question already has answers here:
How do I return the response from an asynchronous call?
(41 answers)
Closed 3 months ago.
I am trying to use a Node.JS application to make and receive API requests. It does a get request to another server using Axios with data it receives from an API call it receives. The second snippet is when the script returns the data from the call in. It will actually take it and write to the console, but it won't send it back in the second API.
function axiosTest() {
axios.get(url)
.then(function (response) {
console.log(response.data);
// I need this data here ^^
return response.data;
})
.catch(function (error) {
console.log(error);
});
}
...
axiosTestResult = axiosTest();
response.json({message: "Request received!", data: axiosTestResult});
I'm aware this is wrong, I'm just trying to find a way to make it work. The only way I can seem to get data out of it is through console.log, which isn't helpful in my situation.
The issue is that the original axiosTest() function isn't returning the promise. Here's an extended explanation for clarity:
function axiosTest() {
// create a promise for the axios request
const promise = axios.get(url)
// using .then, create a new promise which extracts the data
const dataPromise = promise.then((response) => response.data)
// return it
return dataPromise
}
// now we can use that data from the outside!
axiosTest()
.then(data => {
response.json({ message: 'Request received!', data })
})
.catch(err => console.log(err))
The function can be written more succinctly:
function axiosTest() {
return axios.get(url).then(response => response.data)
}
Or with async/await:
async function axiosTest() {
const response = await axios.get(url)
return response.data
}
Guide on using promises
Info on async functions
I know this post is old. But i have seen several attempts of guys trying to answer using async and await but getting it wrong. This should clear it up for any new references
UPDATE: May 2022
This answer is still having lots of interest and have updated it to use arrow functions
const axiosTest = async () {
try {
const {data:response} = await axios.get(url) //use data destructuring to get data from the promise object
return response
}
catch (error) {
console.log(error);
}
}
you can populate the data you want with a simple callback function,
let's say we have a list named lst that we want to populate,
we have a function that pupulates pupulates list,
const lst = [];
const populateData = (data) => {lst.push(data)}
now we can pass the callback function to the function which is making the axios call and we can pupulate the list when we get data from response.
now we make our function that makes the request and pass populateData as a callback function.
function axiosTest (populateData) {
axios.get(url)
.then(function(response){
populateData(response.data);
})
.catch(function(error){
console.log(error);
});
}
The axios library creates a Promise() object. Promise is a built-in object in JavaScript ES6. When this object is instantiated using the new keyword, it takes a function as an argument. This single function in turn takes two arguments, each of which are also functions — resolve and reject.
Promises execute the client side code and, due to cool Javascript asynchronous flow, could eventually resolve one or two things, that resolution (generally considered to be a semantically equivalent to a Promise's success), or that rejection (widely considered to be an erroneous resolution). For instance, we can hold a reference to some Promise object which comprises a function that will eventually return a response object (that would be contained in the Promise object). So one way we could use such a promise is wait for the promise to resolve to some kind of response.
You might raise we don't want to be waiting seconds or so for our API to return a call! We want our UI to be able to do things while waiting for the API response. Failing that we would have a very slow user interface. So how do we handle this problem?
Well a Promise is asynchronous. In a standard implementation of engines responsible for executing Javascript code (such as Node, or the common browser) it will resolve in another process while we don't know in advance what the result of the promise will be. A usual strategy is to then send our functions (i.e. a React setState function for a class) to the promise, resolved depending on some kind of condition (dependent on our choice of library). This will result in our local Javascript objects being updated based on promise resolution. So instead of getters and setters (in traditional OOP) you can think of functions that you might send to your asynchronous methods.
I'll use Fetch in this example so you can try to understand what's going on in the promise and see if you can replicate my ideas within your axios code. Fetch is basically similar to axios without the innate JSON conversion, and has a different flow for resolving promises (which you should refer to the axios documentation to learn).
GetCache.js
const base_endpoint = BaseEndpoint + "cache/";
// Default function is going to take a selection, date, and a callback to execute.
// We're going to call the base endpoint and selection string passed to the original function.
// This will make our endpoint.
export default (selection, date, callback) => {
fetch(base_endpoint + selection + "/" + date)
// If the response is not within a 500 (according to Fetch docs) our promise object
// will _eventually_ resolve to a response.
.then(res => {
// Lets check the status of the response to make sure it's good.
if (res.status >= 400 && res.status < 600) {
throw new Error("Bad response");
}
// Let's also check the headers to make sure that the server "reckons" its serving
//up json
if (!res.headers.get("content-type").includes("application/json")) {
throw new TypeError("Response not JSON");
}
return res.json();
})
// Fulfilling these conditions lets return the data. But how do we get it out of the promise?
.then(data => {
// Using the function we passed to our original function silly! Since we've error
// handled above, we're ready to pass the response data as a callback.
callback(data);
})
// Fetch's promise will throw an error by default if the webserver returns a 500
// response (as notified by the response code in the HTTP header).
.catch(err => console.error(err));
};
Now we've written our GetCache method, lets see what it looks like to update a React component's state as an example...
Some React Component.jsx
// Make sure you import GetCache from GetCache.js!
resolveData() {
const { mySelection, date } = this.state; // We could also use props or pass to the function to acquire our selection and date.
const setData = data => {
this.setState({
data: data,
loading: false
// We could set loading to true and display a wee spinner
// while waiting for our response data,
// or rely on the local state of data being null.
});
};
GetCache("mySelelection", date, setData);
}
Ultimately, you don't "return" data as such, I mean you can but it's more idiomatic to change your way of thinking... Now we are sending data to asynchronous methods.
Happy Coding!
axiosTest() needs to return axios.get, which in turn returns a Promise.
From there, then can be used to execute a function when said Promise resolves.
See Promise for more info.
Alternatively, await can be used from within the scope of some async function.
// Dummy Url.
const url = 'https://jsonplaceholder.typicode.com/posts/1'
// Axios Test.
const axiosTest = axios.get
// Axios Test Data.
axiosTest(url).then(function(axiosTestResult) {
console.log('response.JSON:', {
message: 'Request received',
data: axiosTestResult.data
})
})
<script src="https://cdnjs.cloudflare.com/ajax/libs/axios/0.18.0/axios.js"></script>
IMO extremely important rule of thumb for your client side js code is to keep separated the data handling and ui building logic into different funcs, which is also valid for axios data fetching ... in this way your control flow and error handlings will be much more simple and easier to manage, as it could be seen from this
ok fetch
and this
NOK fetch
<script src="https://unpkg.com/axios/dist/axios.min.js"></script>
<script>
function getUrlParams (){
var url_params = new URLSearchParams();
if( window.location.toString().indexOf("?") != -1) {
var href_part = window.location.search.split('?')[1]
href_part.replace(/([^=&]+)=([^&]*)/g,
function(m, key, value) {
var attr = decodeURIComponent(key)
var val = decodeURIComponent(value)
url_params.append(attr,val);
});
}
// for(var pair of url_params.entries()) { consolas.log(pair[0]+ '->'+ pair[1]); }
return url_params ;
}
function getServerData (url, urlParams ){
if ( typeof url_params == "undefined" ) { urlParams = getUrlParams() }
return axios.get(url , { params: urlParams } )
.then(response => {
return response ;
})
.catch(function(error) {
console.error ( error )
return error.response;
})
}
// Action !!!
getServerData(url , url_params)
.then( response => {
if ( response.status === 204 ) {
var warningMsg = response.statusText
console.warn ( warningMsg )
return
} else if ( response.status === 404 || response.status === 400) {
var errorMsg = response.statusText // + ": " + response.data.msg // this is my api
console.error( errorMsg )
return ;
} else {
var data = response.data
var dataType = (typeof data)
if ( dataType === 'undefined' ) {
var msg = 'unexpected error occurred while fetching data !!!'
// pass here to the ui change method the msg aka
// showMyMsg ( msg , "error")
} else {
var items = data.dat // obs this is my api aka "dat" attribute - that is whatever happens to be your json key to get the data from
// call here the ui building method
// BuildList ( items )
}
return
}
})
</script>
After 6 hours of fluttering, I realized it was a one-line problem. If you are interfering with the axios life-cycle, you may have forgotten this line:
componentDidMount() {
this.requestInterceptor = axios.interceptors.request.use((request) => {
this.updateApiCallFor(request.url, true);
return request;
});
this.responseInterceptor = axios.interceptors.response.use((response) => {
this.updateApiCallFor(response.config.url, false);
return response; // THIS LINE IS IMPORTANT !
}, (error) => {
this.updateApiCallFor(error.config.url, false);
throw error;
});
async makes a function return a Promise
await makes a function wait for a Promise
code async/await
// https://www.npmjs.com/package/axios
const axios = require('axios')
/* --- */
async function axiosTest() {
let promiseAxios = axios.get( 'https://example.com' )
/* --- */
console.log( await promiseAxios )
}
/* --- */
axiosTest()
replit.com Stackoverflow - Returning data from Axios API
replit.com Stackoverflow - How to return values from async
code async/await with return
// https://www.npmjs.com/package/axios
const axios = require('axios')
/* --- */
async function axiosTest() {
console.log( await promiseAxios() )
}
/* --- */
axiosTest()
/* --- */
// create function for promise axios and return it
function promiseAxios() {
return axios.get( 'https://example.com' )
}
replit.com Stackoverflow - Returning data from Axios API - return
replit.com Stackoverflow - How to return values from async - return
Try this,
function axiosTest() {
axios.get(url)
.then(response => response.data)
.catch(error => error);
}
async function getResponse () {
const response = await axiosTest();
console.log(response);
}
getResponse()
It works, but each function where you want to get the response needs to be an async function or use an additional .then() callback.
function axiosTest() {
axios.get(url)
.then(response => response.data)
.catch(error => error);
}
async function getResponse () {
axiosTest().then(response => {
console.log(response)
});
}
getResponse()
If anyone knows a way to avoid this please do tell.
Also checkout Katsiaryna (Kate) Lupachova's article on Dev.to. I think it will help.
async handleResponse(){
const result = await this.axiosTest();
}
async axiosTest () {
return await axios.get(url)
.then(function (response) {
console.log(response.data);
return response.data;})
.catch(function (error) {
console.log(error);
});
}
You can find check https://flaviocopes.com/axios/#post-requests url and find some relevant information in the GET section of this post.
You can use Async - Await:
async function axiosTest() {
const response = await axios.get(url);
const data = await response.json();
}
I appreciate that there are many questions on this but I can't seem to find a relevant answer.
I am using a Meteor call with a callback to a method on the server that shrinks an URL via bitly, but although this runs on the server, I am getting a undefined response back on the client.
Any ideas here is the code?
Client
Meteor.call('bitlyShrink','http://test.com', function(error, response) {
console.log(error);
console.log(response);
})
Server
Meteor.methods({
bitlyShrink(longurl) {
check (longurl, String);
const BitlyClient = require('bitly'),
bitly = BitlyClient('token');
bitly.shorten( longurl )
.then( function ( response ) {
console.log(response);
return response;
})
.catch( (error ) => {
return error;
});
}
});
That's a common mistake made while using Promises in Meteor methods.
To make Meteor resolve a Promise and return result to a client you should return the Promise at the end of this method:
Meteor.methods({
bitlyShrink(longurl) {
check (longurl, String);
const BitlyClient = require('bitly'),
bitly = BitlyClient('token');
const bitlyPromise = bitly.shorten(longurl);
// do something else, if needed
return bitlyPromise;
}
});
You should not add .catch(), it will be added by Meteor automatically.
Useful article to read: Using Promises and async/await in Meteor.
Similar issues have been posted, but none quite match what I've run into. I'm doing a simple POST to an internal server to get back product data. The call is successful and I see the JSON data correctly logging to my terminal when I do a console.log on the server side. The issue arises on the client side, when in the callback, the result and error both are undefined.
Server:
Meteor.methods({
ProductSearch: function(searchTerm) {
var method = 'POST';
var url = 'server';
var options = {
headers:{"content-type":"application/json"},
data: {
query:"trees"
}
};
return HTTP.call(method, url, options, function (error, result) {
if (error) {
console.log("ERROR: ", result.statusCode, result.content);
} else {
var txt = JSON.parse(result.content);
console.log("SUCCESS: Found "+txt.totalResults+" products");
}
});
}
});
Client:
Meteor.call('ProductSearch', searchTerm, function (error, result) {
if (error) {
console.log("error occured on receiving data on server. ", error );
} else {
var respJson = JSON.parse(result.content);
Session.set("productSearchResults", respJson);
}
});
When I log the values of error, and result on callback, they are both undefined, and I get the following error: Exception in delivering result of invoking 'ProductSearch': TypeError: Cannot read property 'content' of undefined
In your server-side method, you're not correctly returning the result of the HTTP.call, since you're using the asynchronous version, HTTP.call will return undefined and the result will only be accessible in the callback.
Use the synchronous version of HTTP.call instead and you'll be fine.
try{
var result = HTTP.call(method, url, options);
return JSON.parse(result.content);
}
catch(exception){
console.log(exception);
}
See the corresponding docs for HTTP.call for additional information.
asyncCallback Function
Optional callback. If passed, the method runs
asynchronously, instead of synchronously, and calls asyncCallback. On
the client, this callback is required.
https://docs.meteor.com/#/full/http_call