add support for custom columns

It would be nice to have suppport for custom columns, with the ability to

create new columns
set the column value
show the columns in calibredb-show-mode

I am guessing that the columns are an additional table in the sql database? So they would be custom sql queries. This is what I am currently using to manage a "read" column to track read status, but it is slow because it calls the cli.

(defun calibredb-args (&key quotes &rest args)
  (apply #'format `(,(s-repeat (length args) (if quotes "'%s' " "%s "))
                    ,@args)))

(defun calibredb-add-column (label name datatype)
  (calibredb-command
   :command "add_custom_column"
   :library (calibredb-arg-library 'local)
   :input (calibredb-args label name datatype)))

(defun calibredb-arg-library (&optional use-local)
  (format "--library-path %s"
          (if-let (url (and (null use-local)
                            (calibredb-check-server)))
              url
            (calibredb-root-dir-quote))))

(defun calibredb-add-read-column ()
  (let* ((columns (calibredb-command
                   :command "custom_columns"
                   :library (calibredb-arg-library 'local)))
         (cols (split-string columns "\n")))
    (unless (stringp (catch 'match
                       (mapc (lambda (x) (and (string-prefix-p "read_status" x)
                                         (throw 'match x))) cols)))
      (calibredb-add-column "read_status" "Read Status" "bool"))))

(defun calibredb-check-server ()
  (and (bound-and-true-p calibredb-server-host)
       (bound-and-true-p calibredb-server-port)
       (processp (ignore-errors (open-network-stream "" nil calibredb-server-host calibredb-server-port)))
       (concat "http://" calibredb-server-host ":" calibredb-server-port)))

(defun calibredb-set-custom (column id value)
  (calibredb-command
   :library (calibredb-arg-library 'local)
   :command "set_custom"
   :input (calibredb-args :key nil column id value)))

(defun calibredb-candidate-key (key &optional candidate)
  (car (alist-get :id
                  (caar (or candidate
                            (calibredb-find-candidate-at-point))))))

(defun calibredb-set-read (&optional candidate)
  (calibredb-set-custom "read_status"
                        (calibredb-candidate-key :id)
                        "true"))

(defun calibredb-set-custom-at-point (col val)
  (interactive "sColumn: \nsValue: ")
  (calibredb-set-custom col
                        (calibredb-candidate-key :id)
                        val))

;; keybinding for doom
(map! :map calibredb-show-mode-map
      :nv "C" #'calibredb-set-custom-at-point)

chenyanming / calibredb.el

add support for custom columns #48