Feature request: Allow user to define function for PDF file name when downloading automatically from the web

[nonducor]

I suggest to extend doi-utils with a functionality that allows the user to specify a function to return the PDF file name when downloading it from the internet (in functions doi-utils-async-download-pdf and doi-utils-get-bibtex-entry-pdf).

Today this is hardcoded to be the entry's key (which happen not to work with my workflow, that uses the title).

The changes would be:

1. Adding a new defcustom for this function (with a default for the current behaviour):

(defcustom doi-utils-get-downloaded-pdf-name
  '(lambda () (cdr (assoc "=key=" (bibtex-parse-entry))))
  "The function to create the pdf file name from the bibtex entry.
Defaults to using the `key' value as the file name."
  :type 'function
  :group 'doi-utils)

2. Change in doi-utils-async-download-pdf to use it:

@@ -665,7 +673,7 @@ too. "
           (doi (replace-regexp-in-string
                 "https?://\\(dx.\\)?.doi.org/" ""
                 (bibtex-autokey-get-field "doi")))
-          (key (cdr (assoc "=key=" (bibtex-parse-entry))))
+          (base-name (funcall doi-utils-get-downloaded-pdf-name))
           (pdf-url)
           (pdf-file))
 
@@ -677,7 +685,7 @@ too. "
                      (car bibtex-completion-library-path))
                     (t
                      (completing-read "Dir: " bibtex-completion-library-path)))
-                   key ".pdf"))
+                   base-name ".pdf"))
 
       (unless doi (error "No DOI found to get a pdf for"))

3. Do the same change in doi-utils-get-bibtex-entry-pdf:

@@ -737,7 +745,7 @@ checked."
           (doi (replace-regexp-in-string
                 "https?://\\(dx.\\)?.doi.org/" ""
                 (bibtex-autokey-get-field "doi")))
-          (key (cdr (assoc "=key=" (bibtex-parse-entry))))
+          (base-name (funcall doi-utils-get-downloaded-pdf-name))
           (pdf-url)
           (pdf-file))
 
@@ -749,7 +757,7 @@ checked."
                      (car bibtex-completion-library-path))
                     (t
                      (completing-read "Dir: " bibtex-completion-library-path)))
-                   key ".pdf"))
+                   base-name ".pdf"))
       ;; now get file if needed.
       (unless (file-exists-p pdf-file)
        (cond

I can submit a pull request if this proposal is acceptable, or change the defcustom/variable names to make it more adequate.

[jkitchin]

This seems reasonable. Make sure the current behavior remains the default behavior. I think you may need to modify something in how bibtex-completion finds the pdf on your end, or store that file name as a file field in the bibtex entry.