How to use Callback function on successful HTTP request in Angular2?

Question

am getting the details from a service and assigning it to an loginDetailsArray array. now i need to call the functions() only after getting the data successful. i just tried to call functions() directly, but it is reading that function before getting the data. i was thinking about using call back function here. but as am new to this, i have no idea of how to get it. Thanks in advance.

loadLoginDetails() {

  this.customerService.getLoginDetails().subscribe(res => {

    this.loginDetailsArray = res.json();
  });
}


functions() {

    var minLength = this.loginDetailsArray.rules.username.minlength;
    var maxLength = this.loginDetailsArray.rules.username.maxlength;
    var pattern = this.loginDetailsArray.rules.username.pattern;
    }

TanguyB · Accepted Answer · 2017-09-15 07:00:43Z

1

When consuming your service, you get 3 responses, 1 for the data, 1 for the error & 1 for when the call is completed.

loadLoginDetails() {
    this.customerService.getLoginDetails().subscribe(
        res => {
            //Code if your response has data.
        },
        error => {
            //Code if your response has error.
        },
        () => {
            //Code when your request is finished.
        }
    );
}

You can either call your functions from the

res => {}

if you want it to run only if you had a successful response, if you want to run it regardless of your response, run it from

() => {}

Regards!

answered Sep 15, 2017 at 7:00

TanguyB

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Comments

Robin-Hoodie · Accepted Answer · 2017-09-15 06:51:54Z

1

This should just work?

loadLoginDetails() {

  this.customerService.getLoginDetails().subscribe(res => {
    this.loginDetailsArray = res.json();
    this.functions();
  });
}

answered Sep 15, 2017 at 6:51

Robin-Hoodie

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1 Comment

Nandha Kumar Over a year ago

yes. but if i pass that loadLoginDetails() function in ngOnInit, and try to get the data,it is showing undefined or it is empty. because as it is asynchronous before getting the data ir is calling functions()

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