Rails7 Active Storage: Why Does the alt Attribute Show a Numeric Identifier in Production?

The difference you’re seeing is likely due to how the file’s metadata is stored and processed between your development and production setups. In development (using the local disk service) the original filename is preserved and returned as expected. In production (often using a cloud service with Active Storage), the original filename may be replaced with a unique key or identifier (for caching, processing, or security reasons) when the file is uploaded or transformed.

Here are a few points to consider:

• Active Storage Behavior:
  Active Storage attaches metadata—including the filename—to each blob. However, when files go through transformations or are cached in production (for example, when generating variant URLs), the stored filename may change to a generated identifier rather than the original uploaded name.

• Service Differences:
  In development you’re likely using the disk service which keeps the original filename, whereas production usually uses a service like Amazon S3. This can affect how the metadata (including the filename) is stored and retrieved.

• Explicit Alt Text:
  Because the default behavior of Rails (for example, in the image_tag helper) is to show the file’s filename if no alt text is provided, you might see a number or key (like “1000043.jpg”) in production. To ensure consistency and clarity in your alt text, consider explicitly providing the alt text instead of relying on the default filename.

For example, you could store the intended display name separately or convert the filename to a string explicitly (if not already doing so):

ERBCopied
<img class="card-img-top" alt="<%= store.main_image.blob.filename.to_s %>" draggable="false" src="<%= my_store_url(store) %>" />

Ultimately, if you need to show the original file’s name consistently across environments, you might need to either:

• Ensure the file’s original metadata is preserved on upload, or
• Store the original filename in another attribute for use in your views.

This behavior is a result of how Active Storage manages file uploads and transformations, and it’s common to see such differences between development and production setups.