How to Successfully Download Files from Your WebApi/MVC App in Angular2 ?

Effective File Downloading with Angular2

In your Angular2 application, you've encountered difficulties saving downloaded files from your WebApi / MVC app. Let's delve into your issue and provide a solution.

Your component's code, as provided, utilizes the Blob() constructor to create a file from the received data. However, you face challenges with the URL.createObjectURL function, which is not available in the current ECMAScript specifications.

The solution stems from the nature of observables within Angular2 . The observable used for downloading the file executes in a different context, resulting in the issue you encounter. To address this, we need to modify the code to subscribe to the observable and execute the file creation and saving logic within that subscription.

One effective approach is to refactor your downloadfile() method to subscribe to the observable as follows:

downloadfile(type: string){
  this.pservice.downloadfile(this.rundata.name, type)
    .subscribe(data => {
      this.downloadFile(data); // Call a separate function to handle file creation and saving
    },
    error => console.log("Error downloading the file."),
    () => console.log('Completed file download.'));
}

In this updated method, we introduce a new downloadFile() function that is responsible for creating the file and initiating the download.

downloadFile(data: Response) {
  const blob = new Blob([data], { type: "application/octet-stream" });
  const url = window.URL.createObjectURL(blob);
  window.open(url);
}

By subscribing to the observable and defining the downloadFile() function, we ensure that the file creation and saving take place within the correct context, allowing you to successfully save and open the downloaded file.

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