Adding a custom has: field for my paper notes

[danielnemenyi]

As well as Org mode notes, I keep paper notes of texts I read (well, I draw maps of them), so I wanted citar to be able to show only items with an associated map (ie, be able to use has:map), as well as to display their physical location. Thought I would share in case anyone else out there might be wanting something similar.

In my BiBLaTeX file I've added my own field notelocation where I store the location of the map. For example

@Book{innis-1986-empir-civil,
  author = 	 {Innis, Harold A.},
  title = 	 {Empire \& Communications},
  year = 	 1986,
  editor = 	 {Godfrey, David},
  publisher = {Press Porcépic},
  notelocation = {map:germany/book2017},
  file = {~/Ebooks/Philosophy/Innis-Harold/harold-i-innis-empire-and-communications-1.pdf},
  location =  {Victoria \& Toronto}}

Now I need to process this into citar. I basically just copied and customized the symbols related to importing links from citar.el.

(defcustom citar-map-fields '((notelocation . "%s"))
  "Bibliography fields to parse into map.

Association list whose keys are symbols naming bibliography
fields and values are URL strings. In each URL, \"%s\" is
replaced by the contents of the corresponding field."
  :group 'citar
  :type '(alist :key-type symbol :value-type string))

(defun citar-has-maps ()
  "Return predicate testing whether entry has map.

Return a function that takes CITEKEY and returns non-nil when the
corresponding bibliography entry has associated map. Map's
existence is sought by presence of notelocation field. See the
documentation of `citar-has-files' and `citar-has-notes', which
have similar usage."
  (let ((notelocationfields (mapcar (lambda (field) (symbol-name (car field))) citar-map-fields)))
    (citar--has-resources
     (apply-partially #'citar-get-field-with-value notelocationfields))))

(defvar citar-indicator-map
   (citar-indicator-create
    :symbol "M"
    :function #'citar-has-maps
    :tag "has:maps"))

Now for the icons:

(setq citar-indicators
  (list citar-indicator-files-icons
	citar-indicator-links-icons
        citar-indicator-notes-icons
	citar-indicator-maps-icons))

(defvar citar-indicator-maps-icons
  (citar-indicator-create
   :symbol (all-the-icons-faicon
            "share-alt"
            :face 'all-the-icons-pink
	    :height 0.6
	    :v-adjust 0.2)
   :function #'citar-has-maps
   :padding " "
   :tag "has:maps"))

And finally, just add the notelocation field to my citar-tempaltes

(setq citar-templates
  '((main . "${author editor:30%sn} ${origdate:4} ${date year issued:4} ${title:48} ${subtitle:48} ${notelocation:22}")
    (suffix . " ${=key= id:15}  ${=type=:8}  ${tags keywords:10}")
    (preview . "${author editor:%etal} (${year issued date}) ${title}, ${journal journaltitle publisher container-title collection-title}.\n")
    (note . "Notes on ${author editor:%etal}, ${title}")))

Now I can run citar and filter by has:maps.

And there we go, now I know that my map exists and where to find it:

[bdarcus]

Very cool!

Feel free to add it to the wiki.

[danielnemenyi]

Thank you! Done: https://github.com/emacs-citar/citar/wiki/Custom-has:-filter