Creating a promise with subscribe in Angular 2 using the http.post method

Question

Creating a promise with subscribe in Angular 2 using the http.post method

I am currently working on creating a function that returns a Promise in the code snippet below (someprovider.ts)

postToPaymentApi(url:string, data:string, options:RequestOptions, order:Order):Promise<any>{
let result =  this.http.post(url, data, options).map(res => res.json())
  .subscribe(data => {
    // all my logic here!
    });
  }, error => {
    console.log(error)
  })

  return new Promise((resolve)=>{
    resolve(result)
  })

}

The issue arises when I call this function and do not receive the expected data. This is because the post request takes some time to complete and the promise resolves before that.

this.postToPaymentApi(url, data, options, order).then(data => {
    console.log(data);
  })

Can anyone help me identify what mistake I am making?

javascript angular typescript ionic2

Answer 1

Answer №1

To successfully create a function that returns a promise, you should adhere to the following structure:

sendToAPI(url:string, data:string, params:RequestOptions, orderInfo:Order):Promise<any >{
   return new Promise((resolve, reject) => {
          this.http.post(url, data, params)
           .map(res => res.json())
           .subscribe(responseData => {
             resolve(responseData);
            }
           }, errorResponse => {
             console.log(errorResponse)
             reject({error: errorResponse});
           });
        });
}

Answer 2

To successfully create a function that returns a promise, you should adhere to the following structure:

sendToAPI(url:string, data:string, params:RequestOptions, orderInfo:Order):Promise<any >{
   return new Promise((resolve, reject) => {
          this.http.post(url, data, params)
           .map(res => res.json())
           .subscribe(responseData => {
             resolve(responseData);
            }
           }, errorResponse => {
             console.log(errorResponse)
             reject({error: errorResponse});
           });
        });
}

Answer 3

Answer №2

Andre, if you want to convert the observable returned by .map() into a promise, you should utilize the toPromise operator. Make sure to return the result of this operator.

return http.post(...).map(...).toPromise()

With the proper promise returned, the calling code can now handle it accordingly:

postToPaymentApi(...).then(
    data => console.log(data)
)

Answer 4

Andre, if you want to convert the observable returned by .map() into a promise, you should utilize the toPromise operator. Make sure to return the result of this operator.

return http.post(...).map(...).toPromise()

With the proper promise returned, the calling code can now handle it accordingly:

postToPaymentApi(...).then(
    data => console.log(data)
)

Creating a promise with subscribe in Angular 2 using the http.post method

Answer №1

Answer №2

Similar questions

I am encountering an issue where the threejs lighting effects, such as pointlight and ambientlight, are not functioning properly in version "three": "^0.164.1". What could be causing this problem

What causes variations in the values returned by outerWidth on different websites?

Using Node.js and Typescript to implement a chain of logical AND operations with an array of any length

Utilizing Google Geochart to map out urban areas within a designated region

Having issues with the ASP.NET Web Api and Angular Frontend integration

Issue Updating Angular 13 formGroup with API Response

Using Jquery Ajax to Send Data with ASP Core ActionResult

Initiating an AJAX request to communicate with a Node.js server

Combining JSON fields and searching based on the combined value within MarkLogic

Is there a way to simultaneously filter by two attributes using mat-select-filter in Angular?

Tips for invoking TypeScript code from Rust WebAssembly

How to Handle Overlapping Divs in HTML?

Invoking a Typescript function from the Highcharts load event

When Firebase authentication signs out users who were previously authenticated, it results in them facing permission denied errors

Creating a slider plugin with Right-to-Left (RTL) support

Critical section in Node.js - transferring data from frontend to JSON file

Tips for showcasing data in the autocomplete feature

Unexpected behavior of Ajax response from PHP

Data from graphql is not being received in Next.js

JavaScript validation code for verifying hostnames with a specified domain name