Working with AngularJS's $q promise and socket.io

Question

Working with AngularJS's $q promise and socket.io

I am interested in creating an angularJS promise that can work seamlessly with socket.io. Currently, I have a callback function set up to handle the response like this:

function request(event, data, callback) {
    socket.emit(event, data);
    socket.on(event, function(d) {
        socket.off(event);
        callback(d);
    });
}

As a result, my code looks something like this:

request('myEvent', 'Hello World !', function(data) {
    ...
});

I am curious if it's possible to implement a promise instead (using the $q service from angular) like so:

request('myEvent', 'Hello World !').then(function(data) {

});

Any insights on how to achieve this would be greatly appreciated! Thank you!

javascript angularjs socket.io

Answer 1

Answer №1

If you're looking to implement a similar solution, consider the following:

function sendRequest(eventType, payload) {
    let promise = new Promise((resolve, reject) => {
        socket.emit(eventType, payload);
        socket.on(eventType, (response) => {
            socket.off(eventType);
            resolve(response);
        });
    });
    
    return promise;
}

Then, you can make use of it like this:

sendRequest('customEvent', 'Hello Universe !').then((responseData) => {

});

Answer 2

If you're looking to implement a similar solution, consider the following:

function sendRequest(eventType, payload) {
    let promise = new Promise((resolve, reject) => {
        socket.emit(eventType, payload);
        socket.on(eventType, (response) => {
            socket.off(eventType);
            resolve(response);
        });
    });
    
    return promise;
}

Then, you can make use of it like this:

sendRequest('customEvent', 'Hello Universe !').then((responseData) => {

});

Answer 3

Answer №2

const sendRequest = (event, payload) => {
  return new Promise((resolve, reject) => {
    socket.emit(event, payload);
      socket.on(event, (response) => {
        socket.off(event);
          resolve(response);
      });
  });
}

Answer 4

const sendRequest = (event, payload) => {
  return new Promise((resolve, reject) => {
    socket.emit(event, payload);
      socket.on(event, (response) => {
        socket.off(event);
          resolve(response);
      });
  });
}

Answer 5

Answer №3

So, when it comes to promises, they can only fulfill or reject once. If the event happens more than once, does it matter to you?

If you're fine with the event firing only once, then go ahead and promise it.

function sendRequest(event, data, callback) {
    socket.emit(event, data);
    socket.on(event, function(responseData) {
        socket.off(event);
        callback(responseData);
    });
}

The updated version is as follows:

function sendPromise(event, data) {
    return $q(function(resolve, reject) {
       socket.emit(event, data);
       socket.on(event, function(responseData) {
           socket.off(event);
           resolve(responseData)
       });
    });
}

Here's how you can use it:

sendPromise('event', data).then(....)

Answer 6

So, when it comes to promises, they can only fulfill or reject once. If the event happens more than once, does it matter to you?

If you're fine with the event firing only once, then go ahead and promise it.

function sendRequest(event, data, callback) {
    socket.emit(event, data);
    socket.on(event, function(responseData) {
        socket.off(event);
        callback(responseData);
    });
}

The updated version is as follows:

function sendPromise(event, data) {
    return $q(function(resolve, reject) {
       socket.emit(event, data);
       socket.on(event, function(responseData) {
           socket.off(event);
           resolve(responseData)
       });
    });
}

Here's how you can use it:

sendPromise('event', data).then(....)

Answer 7

Answer №4

Encountered an issue where wrapping socket.on(event) in a function and calling it multiple times resulted in opening multiple instances. This caused the specific socket event to be called multiple times by the backend. Resolved this by using $rootScope.$on, which ensures only one instance is created.

this.search = (query) => {

    var deferred = $q.defer();

    socket.emit('search', {query: query}) // send data to backend

    $rootScope.$on('search', function(event,data){

        deferred.resolve(data);

    });

    return deferred.promise;
}

//get data back from backend
socket.on('search',(data) => {

    $rootScope.$emit('search',data);

});

The above code snippet is enclosed within an Angularjs service. To retrieve data from socket.on('search'), you can utilize the following:

SocketioService.search('Some query').then( (data) => {
  //do something with the data from the backend
})

This solution may not be optimal, but it effectively resolves the issue :)

Answer 8

Encountered an issue where wrapping socket.on(event) in a function and calling it multiple times resulted in opening multiple instances. This caused the specific socket event to be called multiple times by the backend. Resolved this by using $rootScope.$on, which ensures only one instance is created.

this.search = (query) => {

    var deferred = $q.defer();

    socket.emit('search', {query: query}) // send data to backend

    $rootScope.$on('search', function(event,data){

        deferred.resolve(data);

    });

    return deferred.promise;
}

//get data back from backend
socket.on('search',(data) => {

    $rootScope.$emit('search',data);

});

The above code snippet is enclosed within an Angularjs service. To retrieve data from socket.on('search'), you can utilize the following:

SocketioService.search('Some query').then( (data) => {
  //do something with the data from the backend
})

This solution may not be optimal, but it effectively resolves the issue :)

Working with AngularJS's $q promise and socket.io

Answer №1

Answer №2

Answer №3

Answer №4

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