Setting up RefTeX Tab completion in emacs

Question

I am trying to make Tab completion work with RefTeX. When typing C-c [ and selecting the type of reference I have then a prompt in the minibuffer. When I know the beginning of the bib key I want to enter, say for instance Campbell2006, I would like to type Camp Tab and get Campbell2006 [sole completion].

I have managed to set it up for some documents but I do not understand exactly why it works for them and not for others. I have noticed that for the documents that have proper Tab> completion, the following line is added to the file name_of_tex_file.el created in a auto subfolder:

(TeX-add-style-hook "name_of_tex_file"
(lambda ()
(LaTeX-add-bibliographies
"absolute_path_to_bib")))

I think I obtained this results by adding %%% reftex-default-bibliography: absolute_path_to_bib at the end of my files but this is kind of a nuisance, especially when editing the same file on several computers.

Note that RefTeX is working because when I type C-c [ Camp Ret, I get a list (sometime a bit odd) with the Campbell2006 entry.

I have tried to set the %BIBINPUTS% environment variables with no success. Adding (setq reftex-bibpath-environment-variables '("c:/path_to_bib_file/")) seemed necessary for the C-c [ Camp Ret method to work. It has somehow the same defects as adding a %%% reftex-default-bibliography: to the end of the file and did not provided the Tab completion.

I have tried various combinations of /, //, \\ and \ as file separators when specifying files but I do not know exact which I should use (I'm using emacs in a windows environment). The issue might be as simple as that but as there are lots of parameters to try I fail do determine where is the problem.

What is the step-by-step method to make RefTeX work smoothly with bibliography, including the Tab completion?

EDIT: Completion is possible according to the Reftex manual entry about the command reftex-citation:

The regular expression uses an expanded syntax: &&' is interpreted as and. Thus,aaaa&&bbb' matches entries which contain both aaaa' andbbb'. While entering the regexp, completion on knows [sic] citation keys is possible. `=' is a good regular expression to match all entries in all files.

it does not provide precise guidance on how to make it work though.

Kindahero suggests setting a list of the bib entries and use the completing-read command. This sounds sensible, however I would like to generate this list automatically and it seems feasible because it works with some of my documents.

Answer 1

The documentation of reftex-citation is a bit confusing. It promises completion on known citation keys but I believe "known" refers to keys that have been used previously in this session rather than all keys in the appropriate bibliography. You can use the LaTeX-add-all-bibitems-from-bibtex command defined below to load all keys in your bibliography:

(defun get-bibtex-keys (file)
  (with-current-buffer (find-file-noselect file)
    (mapcar 'car (bibtex-parse-keys))))

(defun LaTeX-add-all-bibitems-from-bibtex ()
  (interactive)
  (mapc 'LaTeX-add-bibitems
        (apply 'append
               (mapcar 'get-bibtex-keys (reftex-get-bibfile-list)))))

Suggestions on appropriate hooks to make this happen automatically are welcome.