I know that with express http request you can add middleware to specific endpoints like so:
function someFunc(req, res, next) {
// some stuff
next()
}
app.get('/users', someFunc, (req, res) => { res.send('data stuff')})
I want to achieve something similar with SocketIO as all I found is using the socket.use(fn) function but this applies to all requests. I would like something like:
function someFunc(data, next) {
// some stuff
next()
}
socket.on('users', someFunc, data => {/*do something*/})
Any way to achieve this? Or something similar?
As far as i know there is not a way to do this but maybe you can just pass your data to that function with callback and use it like that?
function someFunc(data, callback) {
let passed = false;
// do your stuff here with data.
if (passed) {
// passed data again to your callback or edited callback
callback(data);
}
}
socket.on("users", data => someFunc(data, callback));
socket.on("other", data => someFunc(data, callback));
...
socket.on("another", data => someFunc(data, (editedData) => {
console.log(editedData);
}));
Maybe something like this you could use?
Related
I'm making a request to a 3rd party API via NestJS's built in HttpService. I'm trying to simulate a scenario where the initial call to one of this api's endpoints might return an empty array on the first try. I'd like to use RxJS's retryWhen to hit the api again after a delay of 1 second. I'm currently unable to get the unit test to mock the second response however:
it('Retries view account status if needed', (done) => {
jest.spyOn(httpService, 'post')
.mockReturnValueOnce(of(failView)) // mock gets stuck on returning this value
.mockReturnValueOnce(of(successfulView));
const accountId = '0812081208';
const batchNo = '39cba402-bfa9-424c-b265-1c98204df7ea';
const response =client.viewAccountStatus(accountId, batchNo);
response.subscribe(
data => {
expect(data[0].accountNo)
.toBe('0812081208');
expect(data[0].companyName)
.toBe('Some company name');
done();
},
)
});
My implementation is:
viewAccountStatus(accountId: string, batchNo: string): Observable<any> {
const verificationRequest = new VerificationRequest();
verificationRequest.accountNo = accountId;
verificationRequest.batchNo = batchNo;
this.logger.debug(`Calling 3rd party service with batchNo: ${batchNo}`);
const config = {
headers: {
'Content-Type': 'application/json',
},
};
const response = this.httpService.post(url, verificationRequest, config)
.pipe(
map(res => {
console.log(res.data); // always empty
if (res.status >= 400) {
throw new HttpException(res.statusText, res.status);
}
if (!res.data.length) {
this.logger.debug('Response was empty');
throw new HttpException('Account not found', 404);
}
return res.data;
}),
retryWhen(errors => {
this.logger.debug(`Retrying accountId: ${accountId}`);
// It's entirely possible the first call will return an empty array
// So we retry with a backoff
return errors.pipe(
delayWhen(() => timer(1000)),
take(1),
);
}),
);
return response;
}
When logging from inside the initial map, I can see that the array is always empty. It's as if the second mocked value never happens. Perhaps I also have a solid misunderstanding of how observables work and I should somehow be trying to assert against the SECOND value that gets emitted? Regardless, when the observable retries, we should be seeing that second mocked value, right?
I'm also getting
: Timeout - Async callback was not invoked within the 5000ms timeout specified by jest.setTimeout.Timeout - Async callback was not invoked within the 5000ms timeout specified by jest.setTimeout.Error:
On each run... so I'm guessing I'm not calling done() in the right place.
I think the problem is that retryWhen(notifier) will resubscribe to the same source when its notifier emits.
Meaning that if you have
new Observable(s => {
s.next(1);
s.next(2);
s.error(new Error('err!'));
}).pipe(
retryWhen(/* ... */)
)
The callback will be invoked every time the source is re-subscribed. In your example, it will call the logic which is responsible for sending the request, but it won't call the post method again.
The source could be thought of as the Observable's callback: s => { ... }.
What I think you'll have to do is to conditionally choose the source, based on whether the error took place or not.
Maybe you could use mockImplementation:
let hasErr = false;
jest.spyOn(httpService, 'post')
.mockImplementation(
() => hasErr ? of(successView) : (hasErr = true, of(failView))
)
Edit
I think the above does not do anything different, where's what I think mockImplementation should look like:
let err = false;
mockImplementation(
() => new Observable(s => {
if (err) {
s.next(success)
}
else {
err = true;
s.next(fail)
}
})
)
I have a Controller method: DbController.create to create database entries. This is the following format:
create: function (req, res) {
var params = req.body;
Db.create({
...
There is a route for this Controller method:
'POST /createData': 'DbController.create'
I can use CURL to this URL with no problems (curl -X POST --data 'userId="testuser1"' http://localhost:1337/createData), and from my UI code I can call this using sails-io.js and io.socket.post(....).
The problem is that I want to use this from my Service now (DbService). I'm not sure how I can go about this, because simply using DbController.create requires a req and res parameter to be passed, but all I have is the data/params/body.
Thanks
The best way would be to move the create logic in some service method so that it can be used from anywhere in project. Once this is done, then invoke that method with necessary parameters from DbController.create as well as from some other service.
Sample:
// DBService:
createData: (params, callback) => {
Db.create(params)...
}
// DBController:
create: (req, res) => {
const params = req.body;
DBService.createData(params, (err, results) => {
if (err) {
return res.serverError(err);
}
return res.json(results);
});
}
// SomeOtherService:
someMethod: (params, callback) => {
DBService.createData(params, callback);
}
Another way (which will unnecessary make http request) is to make a HTTP call from service to the API endpoint of DbController.create from the service.
Hi I cannot return the value from the function. It's returns undefined. And I don't know why. Below is the code.
function getData() {
axios.get('/task')
.then(response => {
return response.data.tasks;
});
}
//calls the function
getData();
But when i call the function getTaskData, it returns only undefined.
Please help. Thanks.
You're dealing with Promises in this case. They do not behave like a typical function in JavaScript. I would recommend starting with some basics:
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise
As to your question, getData does not return anything, nor is there a getTaskData in the code you've provided.
As said in the previews response you’re dealing with promise,
You need to wait finishing you’re Ajax request and then you deal with response,
In your code you can do like this
async function getData() {
const response = await axios.get('/task')
return response
}
Call function with callback for the success and failure cases of the Promise
getData()
.then(response => {
console.log(response.data.tasks)
})
.catch(error => {
console.log("ERROR")
})
I have a problem with redux trying to load initial data with an asynchronous call to my backend API that returns a JSON. Right now, I'm trying to load a bunch of different articles, but I have no idea how to load it asynchronously. Since it is an initial set of data, should I load it synchronously? If yes, then how would I acheive a synchronous call to my API? If not, how would I go about solving this problem asynchronously?
Right now, I have static json data, data/articles.js that creates a default state in store.js.
Thanks
You should use a redux-thunk middleware, which allows you to dispatch async actions and a fetch library (for example) for downloading your initial data.
So:
1) create an action which fetch your data, example:
export function fetchData() {
const options = {
method: 'GET',
headers: {
'Authorization': 'Client-ID xx' // if theres any needed
}
}
return (dispatch) => {
return fetch('yourUrl.json', options)
.then(response => response.json())
.then(data => dispatch(receiveYourData(data)))
.catch(err => console.log(err));
}
}
receiveYourData is a action which will place your data in your state, example:
export function receiveYourData (payload = []) {
return {
type: RECEIVE_DATA,
payload: payload
}
}
Of course you have to write action handler, which after dispatching an action, will place your data in your state.
If you have your setup (similar to above), you should dispatch fetchData in your componentDidMount lifecycle method (its one of the option of course :) ).
If you dont know how to do particular parts, you can refer to this Example.
Also official async example may be helpful :)
I also had this problem. It turned out that you have to add a lot of code for this simple task. So I simplified this process and created a package for async loading of initial state in redux - redux-async-initial-state.
You can check out examples and in your case in the end your store creator will look like this:
// Load initial state function
const loadStore = () => {
return Promise(resolve => {
fetch('/data/articles.js')
.then(response => response.json())
.then(resolve);
});
}
const storeCreator = applyMiddleware(asyncInitialState.middleware(loadStore));
const store = storeCreator(reducer);
I am using NodeJS. One of my function (lets call it funcOne) receives some input which I pass to another function (lets call it funcTwo) which produces some output.
Before I pass the input to funcTwo I need to make an Ajax call to an endpoint passing the input and then I must pass the output produced by the AJAX call to funcTwo. funcTwo should be called only when the AJAX call is successful.
How can I achieve this in NodeJS. I wonder if Q Library can be utilized in this case
Using request
function funcOne(input) {
var request = require('request');
request.post(someUrl, {json: true, body: input}, function(err, res, body) {
if (!err && res.statusCode === 200) {
funcTwo(body, function(err, output) {
console.log(err, output);
});
}
});
}
function funcTwo(input, callback) {
// process input
callback(null, input);
}
Edit: Since request is now deprecated you can find alternatives here
Since request is deprecated. I recommend working with axios.
npm install axios#0.16.2
const axios = require('axios');
axios.get('https://api.nasa.gov/planetary/apod?api_key=DEMO_KEY')
.then(response => {
console.log(response.data.url);
console.log(response.data.explanation);
})
.catch(error => {
console.log(error);
});
Using the standard http library to make requests will require more effort to parse/get data. For someone who was used to making AJAX request purely in Java/JavaScript I found axios to be easy to pick up.
https://www.twilio.com/blog/2017/08/http-requests-in-node-js.html