PayloadCMS: Inconsistent URL Storage In Upload Collections

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PayloadCMS: Inconsistent URL Storage in Upload Collections

Hey guys! Today, we're diving into a rather intriguing issue in PayloadCMS that has to do with how URL and thumbnailURL fields are stored (or, more accurately, not stored) in the database when dealing with upload collections. It's a bit of a rabbit hole, but stick with me, and we'll get to the bottom of it. So let's begin our guide.

The Bug: A Deep Dive

What's Happening?

So, here's the deal: when you're creating a new document in a PayloadCMS collection that's set up for uploads (think uploading files, images, etc.), the url and thumbnailURL fields aren't initially saved in the database. It's like they're playing hide-and-seek! These fields only decide to stick around after you save the document a second time. For example, this might happen when you update the alt text for an image. Weird, right?

This isn't picky about storage adapters either; it happens whether you're not using one at all or if you've got one all set up. Even the url fields for different image sizes get caught up in this mess.

Why Does This Happen?

Now, the why is the juicy part. If you peek into Payload’s source code (specifically, the getBaseFields.ts file), you'll notice that the default url field, along with thumbnailURL and those url fields for image sizes, get an afterRead hook attached automatically. This hook calls a function called generateURL. So, what does this mean?

Well, it explains why the url only gets stored after the first update. During the read operation from the database, this generateURL function kicks in and creates the URL based on the filename. This generated URL then becomes part of the document and gets saved upon the next update.

The Heart of the Matter

In a nutshell, the inconsistency arises because the URL isn't being stored right away. It's generated on the fly when the document is read, which leads to this delayed persistence.

Expected vs. Actual Behavior

What We Want

Ideally, the url fields should behave consistently. There are two ways this could go:

  1. Virtual Fields: The url fields could be virtual, meaning they're never stored in the database but always generated on the fly.
  2. Consistent Storage: The url fields should always be stored in the database right from the get-go.

What We Get

Instead, what's happening is a bit of a mix-up. The url fields aren't stored initially upon upload, but they do get saved after the first update. This inconsistency can lead to some unpredictable behavior, as we'll see.

The Suggested Fix: Making URLs Virtual

Why Virtual Fields Might Be the Answer

One potential solution floating around is to make these url fields virtual by adding virtual: true in Payload's configuration. This means the URLs would always be generated dynamically and never stored in the database. Sounds neat, but why is this a good idea?

Well, consider a scenario where someone enables disablePayloadAccessControl after there are already images in the database. If the URLs are stored, they might incorrectly point to /api/media instead of the actual file source. Making them virtual ensures they're always generated correctly, avoiding this pitfall.

Real-World Impact: The adminThumbnail Function

The Problem

This issue isn't just theoretical; it can cause headaches in real-world scenarios. One user noticed this when their custom adminThumbnail function sometimes received the originalDoc with a url field set and sometimes not. This inconsistency was a direct result of the URL field not being stored initially.

A Practical Example

Imagine you have a function that generates thumbnails for images in your admin panel. If this function relies on the url field, it'll work fine after the first update, but it might stumble upon initial upload. This can lead to broken thumbnails or other unexpected behavior, which isn't a great user experience.

How to Reproduce the Bug

Step-by-Step Guide

Want to see this bug in action? Here’s how you can reproduce it:

  1. Set up a Payload App: Grab the reproduction repository linked in the original bug report. It’s a blank template, so you'll start fresh.
  2. Run the App: Fire up the Payload app.
  3. Create a Media Document: Upload a file to create a new media document.
  4. Inspect the Database: Check the URL field in your database. Notice it's missing? Spooky!
  5. Update the Document: Make a small change, like updating the alt text.
  6. Inspect the Database Again: Now, check the URL field. Voila! It’s there. Magic!

Visual Aid

If you're more of a visual learner, there’s even a reproduction video available that walks you through these steps. It’s always helpful to see it in action.

Affected Areas

Core Issues

This bug primarily affects the core functionality of PayloadCMS, specifically the way it handles uploads and stores related data. It’s not limited to a specific storage adapter or configuration, making it a pretty widespread issue.

Environment Details

The Tech Stack

To give you a clearer picture, here’s the environment info from the original bug report:

  • Node: 24.3.0
  • npm: 11.4.2
  • Payload: 3.63.0
  • Next.js: 15.4.7
  • MongoDB: As the database
  • React: 19.1.0

This setup gives you an idea of the versions and packages involved, which can be crucial for debugging and fixing the issue.

Conclusion: Wrapping Up the Mystery

So, guys, we've journeyed through the curious case of the missing URL fields in PayloadCMS upload collections. We've seen how the url and thumbnailURL fields aren't consistently stored in the database, leading to potential issues with thumbnail generation and other functionalities. The suggested fix of making these fields virtual seems promising, but it’s something that needs careful consideration and testing.

Understanding these nuances is crucial for building robust and reliable applications with PayloadCMS. Keep an eye on this issue, and hopefully, we'll see a fix in future releases. Until then, happy coding, and may your URLs always be where you expect them to be!