File upload: how and why we rename the files?
When files are uploaded to a system, they are often renamed to ensure compatibility with the file system and to avoid any technical issues such as bugs or errors like the 404 not found error. The renaming process involves:
Removing Forbidden Characters: Certain characters are not allowed in URLs because they can cause confusion with URL syntax. For instance, `#` can be mistaken for a fragment identifier, and `?` can be confused with a query string. The regular expression provided (`^[A-Za-z0-9\._~:/?#\[\]@!$&'()*+,;=%€\\©]+$`) indicates a set of characters that are considered safe and won't be removed. Any character not matching this pattern will be deleted.
Replacing Accents with Plain ASCII Characters: Accented characters like `à` or `ü` are replaced with their closest ASCII equivalent (`a` and `u`, respectively) to prevent any encoding issues across different systems that may not handle Unicode or other character encodings well. This is particularly important for maintaining compatibility and preventing errors when files are accessed on different platforms or through various protocols.
The specifics of what is deleted and what is replaced are tailored to the requirements of the system and are designed to prevent any issues that might arise from characters that are either reserved for special functions within URLs or are prone to misinterpretation due to varying character encoding standards. This ensures a smoother, more reliable user experience and lessens the risk of encountering technical issues when handling file uploads.