I am currently facing challenges retrieving data from a post request in my Angular/Typescript frontend application connected to an ASP.NET backend

Question

I am currently facing challenges retrieving data from a post request in my Angular/Typescript frontend application connected to an ASP.NET backend

I am currently working on a web application that relies on backend processing. To communicate between my Angular(v14)/Typescript front end and an ASP.NET backend, I am sending a post request.

Backend Code

[HttpPost]
public async Task<string> ProcessExcelFile(IFormFile fileData, IFormCollection data)
{
      string guid = await processor.ProcessFile(fileData, data) //Not important for the question.
    
      return guid;
}

Frontend Code

var guid: string = "";
this.http.post<string>('/api', formData).subscribe(result => {guid = result;});

After debugging, I have confirmed that the backend is being reached successfully and returning the correct data.

However, even though the backend processing may take a few seconds, the frontend "guid" remains empty after the post request is made. What could be causing this issue?

Is the delay in backend processing causing the problem? How can I address this issue?

c#asp.net angular typescript http-post

Answer 1

Answer №1

If the response you're dealing with is in JSON format, you can handle it in the following way:

// Handling Backend Response

{
  "guid": "uniqueId456"
}

let guidValue: string;
this.http.post<any>('/api', formData).subscribe(responseData => {
    guidValue = responseData.guid;
});

If the response isn't in JSON format, could you please provide an example of how it looks?

In case the response consists of plain text:

let guidValue: string;
this.http.post<string>('/api', formData,{ responseType:'text'}).subscribe(responseData => {
    guidValue = responseData;
});

Answer 2

If the response you're dealing with is in JSON format, you can handle it in the following way:

// Handling Backend Response

{
  "guid": "uniqueId456"
}

let guidValue: string;
this.http.post<any>('/api', formData).subscribe(responseData => {
    guidValue = responseData.guid;
});

If the response isn't in JSON format, could you please provide an example of how it looks?

In case the response consists of plain text:

let guidValue: string;
this.http.post<string>('/api', formData,{ responseType:'text'}).subscribe(responseData => {
    guidValue = responseData;
});

Answer 3

Answer №2

Upon reviewing the code snippets, one noticeable aspect is the absence of returning an IActionResult. To potentially address this issue, you might want to try adding this and see if it resolves the problem

[HttpPost]
public async Task<IActionResult> ProcessExcelFile(IFormFile fileData, IFormCollection data)
{
  string guid = await 
  processor.ProcessFile(fileData, data) //Note: not crucial for the question.

  return ok(guid);
}

In essence, this action sends a successful API response with the assigned GUID as the content

Answer 4

Upon reviewing the code snippets, one noticeable aspect is the absence of returning an IActionResult. To potentially address this issue, you might want to try adding this and see if it resolves the problem

[HttpPost]
public async Task<IActionResult> ProcessExcelFile(IFormFile fileData, IFormCollection data)
{
  string guid = await 
  processor.ProcessFile(fileData, data) //Note: not crucial for the question.

  return ok(guid);
}

In essence, this action sends a successful API response with the assigned GUID as the content

Answer 5

Answer №3

Upon closer inspection, it seems that the post request was waiting for the function triggered by a button click on the webpage to complete before finalizing.

To address this issue, I opted to declare the guid variable as a global variable instead of within the same function as the post request. As a result, I am now able to retrieve the accurate data in the guid variable, albeit only after the completion of the button press function.

this.http.post<string>('/api', formData).subscribe(result => {this.guid = result;});

Answer 6

Upon closer inspection, it seems that the post request was waiting for the function triggered by a button click on the webpage to complete before finalizing.

To address this issue, I opted to declare the guid variable as a global variable instead of within the same function as the post request. As a result, I am now able to retrieve the accurate data in the guid variable, albeit only after the completion of the button press function.

this.http.post<string>('/api', formData).subscribe(result => {this.guid = result;});

I am currently facing challenges retrieving data from a post request in my Angular/Typescript frontend application connected to an ASP.NET backend

Answer №1

Answer №2

Answer №3

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