Скачать или смотреть Effortlessly Downloading PDF in Rails 7 from a Binary String

Discover a modern approach to download PDFs in Rails 7 directly from binary strings using the `send_data` method and handle files efficiently without server storage.
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Effortlessly Downloading PDF in Rails 7 from a Binary String

When developing a Rails 7 application that generates PDFs using an external service, you might find yourself in a situation where you receive a binary string representing the PDF. The challenge lies in downloading this PDF directly to the user's device without the need to save the file on your server. In this article, we will guide you through how to achieve this using the send_data method along with a simple adjustment to your controller.

Understanding the Problem

You are likely attempting to provide a seamless user experience by allowing downloadable files generated on-the-fly. However, if your efforts result in the warning message: "No template found for PaymentsController# pdf_download, rendering head :no_content", you know that something is missing in your implementation. This issue arises particularly because Rails expects a view to be rendered if no explicit response is provided.

Solution Overview

To solve this problem, you simply need to implement a few changes in your PaymentsController to ensure that you send the data back to the user correctly. Below, we'll break down the steps required to make this happen.

Step-by-Step Implementation

Update Your Controller Method

In your PaymentsController, modify the pdf_download method to use the send_data function, which will allow you to send the binary data directly to the user’s browser. Here's how you can do it:

[[See Video to Reveal this Text or Code Snippet]]

Key Additions:

Using send_data allows you to send the PDF binary directly.

The disposition option set to 'attachment' prompts the user’s browser to download the file.

Ensure that the PdfGenerator's call method returns the file content.

Return the PDF Content

Ensure that your PdfGenerator class is adjusted to return the binary content instead of saving it to a file. You can refactor it as follows:

[[See Video to Reveal this Text or Code Snippet]]

Make a Link to Trigger the Download

In your view, ensure you have a link that triggers this controller method. For example:

[[See Video to Reveal this Text or Code Snippet]]

This creates a link that sends a POST request to your pdf_download action.

Potential Issues and Considerations

File Overwriting: Beware of the Global Interpreter Lock (GIL) when using a single file name such as invoice.pdf. As your application grows, you might encounter race conditions if multiple requests attempt to create or read the same file. To mitigate this, consider using unique filenames or implement a strategy to generate temp files for each request.

Async Processing: If you plan to introduce asynchronous processing in your app, it is advisable to adapt your handling of file generation to ensure that each invoice file remains distinct and does not clash with others.

Conclusion

By following these steps, you can easily facilitate the downloading of PDFs created from binary strings in your Rails 7 application. Utilizing Rails' built-in send_data method, you avoid unnecessary file storage and provide a smooth user experience.

If you encounter any issues, ensure that your method returns data explicitly and test your implementation thoroughly. Happy coding!