Invoke a fresh constructor within a $get method in Angular's provider

Question

Invoke a fresh constructor within a $get method in Angular's provider

I'm encountering an issue where I am attempting to utilize a function as a constructor inside the `.provider`, but I'm unable to instantiate a new constructor when it's within the `$get`.

Here is my provider setup -

 this.$get = $get;
    $get.$inject = ['checkUrl', '$log', '$location'];

    function $get(checkUrl, $log, $location) {
        return {

            moduleCon: function(name, cb) {
                    //my constructor function
                }

            }

When I try to inject and call it like this

   new  myProvider.$get().moduleCon("name", "cb");

I encounter an injector error.

However, if I move it outside of the $get, it works as follows:

   (inside the provider above the $get)
    this.moduleCon = function(name, cb) {
                    //my constructor function
                }

I need to use `this.`, but then I can successfully call

   new myProvider.moduleCon("name","cb");

And it works correctly. Is there any way to expose it in the $get as a constructor as I am doing here? Thank you!

javascript angularjs

Answer 1

Answer №1

The code you currently have is being interpreted as:

(new myProvider.$get()).moduleCon("name", "cb");

This isn't achieving the desired result. To achieve what you want, you need to write it like this:

new (myProvider.$get().moduleCon)("name", "cb"); // or
new (myProvider.$get()).moduleCon("name", "cb");

It's recommended to avoid creating constructor functions dynamically.

Answer 2

The code you currently have is being interpreted as:

(new myProvider.$get()).moduleCon("name", "cb");

This isn't achieving the desired result. To achieve what you want, you need to write it like this:

new (myProvider.$get().moduleCon)("name", "cb"); // or
new (myProvider.$get()).moduleCon("name", "cb");

It's recommended to avoid creating constructor functions dynamically.

Answer 3

Answer №2

When you invoke myProvider, what you are really invoking is the $get function associated with it. In essence, there is a line of code that triggers the injector's invoke method:

instanceInjector.invoke(provider.$get, provider, undefined, serviceName);

While there are many intricate details at play, the crux of the matter is that the value returned from the $get function is essentially what myProvider represents. If you were attempting something specific, it would be realized by structuring it in this manner:

app.controller('MainCtrl', function($scope, myProvider) {
  myProvider.$get();
});

app.provider('myProvider', function() {
  this.$get = function(){
    return {
      $get: function(){console.log('something isn\'t right here...')}
    }
  };
});

Though this example may seem nonsensical, it serves as a learning experience to grasp the inner workings of this concept better. Remember, the $get function plays a crucial role in retrieving whatever the provider offers. Essentially, a factory mirrors a provider, but with its $get method being the function passed to the app.factory method:

function factory(name, factoryFn) {
    return provider(name, { $get: factoryFn });
}

Answer 4

When you invoke myProvider, what you are really invoking is the $get function associated with it. In essence, there is a line of code that triggers the injector's invoke method:

instanceInjector.invoke(provider.$get, provider, undefined, serviceName);

While there are many intricate details at play, the crux of the matter is that the value returned from the $get function is essentially what myProvider represents. If you were attempting something specific, it would be realized by structuring it in this manner:

app.controller('MainCtrl', function($scope, myProvider) {
  myProvider.$get();
});

app.provider('myProvider', function() {
  this.$get = function(){
    return {
      $get: function(){console.log('something isn\'t right here...')}
    }
  };
});

Though this example may seem nonsensical, it serves as a learning experience to grasp the inner workings of this concept better. Remember, the $get function plays a crucial role in retrieving whatever the provider offers. Essentially, a factory mirrors a provider, but with its $get method being the function passed to the app.factory method:

function factory(name, factoryFn) {
    return provider(name, { $get: factoryFn });
}

Invoke a fresh constructor within a $get method in Angular's provider

Answer №1

Answer №2

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