Set Cookies Before Returning File

Oct 13, 2025 by wbrum.org 93 views

Introduction

When working with web applications, cookies play a crucial role in storing user data and preferences. However, when dealing with file responses, setting multiple cookies can be a challenge. In this article, we will explore the issue of setting multiple cookies when the response is a file, specifically in the context of the Elysia framework.

Understanding the Issue

The problem arises when trying to set multiple cookies in a file response. As seen in the provided code snippet, only the first cookie is set, while the subsequent ones are ignored. This behavior is not expected, as multiple Set-Cookie headers should be sent in the response.

The Code Snippet

import { Elysia } from 'elysia';

new Elysia()
  .get('/', ({ cookie: { foo, baz }, set }) => {
    foo.value = 'foo';
    baz.value = 'baz';

    // also doesn't work
    // set.cookie = {
    //   foo: {
    //     value: 'foo',
    //   },
    //   baz: {
    //     value: 'baz',
    //   },
    // };

    return Bun.file('./package.json');
  })
  .listen(3000);

Expected Behavior

The expected behavior is to see multiple Set-Cookie headers in the response, each representing a different cookie. However, in this case, only one Set-Cookie header is present.

Actual Behavior

The actual behavior is that only one Set-Cookie header is sent in the response, ignoring the subsequent cookie settings.

Additional Information

Bun Version

Bun version: 1.2.4

Elysia Version

Elysia version: 1.2.25

Platform

No response provided

Steps to Reproduce

Create a new Elysia application.
Define a route that returns a file response.
Attempt to set multiple cookies in the response.
Observe that only the first cookie is set.

Possible Causes

File Response: The issue might be related to the file response itself, which could be interfering with the cookie settings.
Cookie Settings: The cookie settings might be incorrect or incomplete, leading to the issue.
Elysia Framework: The Elysia framework might have a limitation or bug that prevents setting multiple cookies in a file response.

Workarounds

Set Cookies Before Returning File: Set the cookies before returning the file response.
Use a Different Response Type: Use a different response type, such as a JSON response, to avoid the issue.
Upgrade Elysia Framework: Upgrade the Elysia framework to the latest version to see if the issue is resolved.

Conclusion

Introduction

In our previous article, we explored the issue of setting multiple cookies when the response is a file in the Elysia framework. We discussed the problem, the code snippet, and the expected and actual behavior. In this article, we will provide a Q&A section to address common questions and concerns related to this issue.

Q: What is the cause of this issue?

A: The cause of this issue is likely related to the file response itself, which could be interfering with the cookie settings. Additionally, the cookie settings might be incorrect or incomplete, leading to the issue.

Q: How can I set multiple cookies when the response is a file?

A: Unfortunately, setting multiple cookies when the response is a file is not currently supported in the Elysia framework. However, you can try setting the cookies before returning the file response or use a different response type, such as a JSON response.

Q: Is this issue specific to the Elysia framework?

A: No, this issue is not specific to the Elysia framework. It is a general issue that can occur in any framework or application that returns a file response.

Q: Can I upgrade the Elysia framework to resolve this issue?

A: Yes, you can try upgrading the Elysia framework to the latest version to see if the issue is resolved. However, this may not necessarily fix the issue, and you may need to explore other workarounds.

Q: What are some alternative solutions to setting multiple cookies when the response is a file?

A: Some alternative solutions include:

Setting the cookies before returning the file response
Using a different response type, such as a JSON response
Storing the cookies in a different location, such as a database or a separate cookie store

Q: How can I troubleshoot this issue?

A: To troubleshoot this issue, you can try the following:

Check the Elysia framework documentation to see if there are any known issues or workarounds
Review the code snippet to ensure that the cookie settings are correct and complete
Use a debugger or logging statements to inspect the cookie settings and the file response

Q: Is there a known fix for this issue?

A: Unfortunately, there is no known fix for this issue in the Elysia framework. However, you can try the workarounds mentioned above or explore other solutions.

Conclusion

Setting multiple cookies when the response is a file can be a challenging issue in the Elysia framework. By understanding the cause of the issue, exploring alternative solutions, and troubleshooting the problem, developers can overcome this limitation and ensure that their web applications function as expected.

Additional Resources

Elysia framework documentation: https://elysia.app/docs/
Elysia framework issues: https://github.com/elysia-app/elysia/issues
Cookie settings documentation: https://developer.mozilla.org/en-US/docs/Web/HTTP/Cookies