Embedding Foreign Characters In Your Content-Disposition Filename Header
Since English is my primary language, I sometimes don't realize that aspects of my web applications don't play nicely with non-US ASCII characters. Such is the case with the "Content-Disposition" header. I've been using it for years; but, only found out last week that the "filename" portion of the Content-Disposition header doesn't naturally handle non-US ASCII characters. Luckily, modern browsers support an extension to the Content-Disposition header that allows for UTF-8 encoded characters.
With some Googling, I came across this page, which has a ton of test cases for the Content-Disposition header. Among the tests, it suggests that you can use a special notation that allows for the standard filename plus a UTF-8 filename with URL-encoded characters.
- <!---
- Query for the files in the directory.
- --
- NOTE: I am doing this so I don't have to embed high-ascii characters
- in the code - I don't think my blog has the proper support for UTF-8
- encoding? Not sure.
- --->
- <cfset files = directoryList( expandPath( "./" ), false, "name", "Data*" ) />
-
- <!--- Isolate the file with foreign characters. --->
- <cfset fileName = files[ 1 ] />
- <cfset filePath = expandPath( fileName ) />
-
- <!---
- By default, the filename portion of the Content-Disposition header
- only allows for US-ASCII values. In order to account for foreign /
- exnteded ASCII values, we have to jump through some funky notation.
-
- In this case, we are attempting to provide fallbacks. The first
- instance of "filename" is for browsers that do not support the RFC
- 5987 encoding (they ignore the filename*= after the filename).
- Then, for browsers that DO support the encoding, they will pick
- up the UTF-8 encoding.
-
- Notice that the UTF-encoded value doesn't need to be quoted since
- the embeded spaces are url-encoded.
- --->
- <cfheader
- name="content-disposition"
- value="attachment; filename=""#fileName#""; filename*=UTF-8''#urlEncodedFormat( fileName )#"
- />
-
- <cfcontent
- type="text/plain; charset=utf-8"
- file="#filePath#"
- />
In this case, the "filename*=UTF-8''" notation will be honored by modern browsers and ignored by older browsers, which will use the "filename" value as the fallback.
When I run the above code, I am prompted for a file download:
| | | | ||
| |  | | ||
| | | |
Notice that the foreign characters (French) are present. This seems to work on all my modern browsers, including the latest releases of IE.
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