How to handle multiple file upload in hunchentoot?

Question

I know how to handle a single file upload in hunchentoot using hunchentoot:post-parameter, but when I add a property multiple, i.e., <input name="file" type="file" multiple="multiple"/>. I got (hunchentoot:post-parameter "file") only for one of them. Is there (and what is ) the mechanism for receiving all files, chosen by user?

Answer 1

The Hunchentoot API does not directly give you access to multiple uploaded files, but you can use (hunchentoot:post-parameters *request*) to retrieve the list of all POST parameters (which includes the uploaded files). This will be an alist, and you can get a list of all uploaded files using standard alist techniques (e.g. (remove "file" (hunchentoot:post-parameters hunchentoot:*request*) :test (complement #'equal) :key #'car)).

Answer 2

This is a rather straight-forward task in hunchentoot. Assuming you have a html <input> element with name="files" and multi="true", you could access all the files associated with the the "files" input like this:

(loop for post-parameter in (hunchentoot:post-parameters*)
            if (equal (car post-parameter) "files")
            collect post-parameter))

This will give you a list whose length should match the number of uploaded files associated with the name "files". Each of the elements will be a list that looks like this:

("files" #P"/temporary/file1" "name of file" "file type")

More information can be found in the very well-documented reference.