gistfile1.clj

;; My two attempts. The first is to make create-database ignore the error return
;; with chain-or. I can't get anything to compile here. Have tried with/without
;; stevedore/script, with/without ~(apply...). 

;; Second attempt: ensure-database-exists function. Uses a defscript. This will
;; output the if statement desired, but at a seemingly random place earlier in the
;; script unrelated to the conditional. It will also not escape as-user or db-name,
;; although it will escape the (format ...). 

(defn create-database
  "Create a database if it does not exist.

   You can specify database parameters by including a keyed parameter called
   :db-parameters, which indicates a vector of strings or keywords that will get
   translated in order to the options to the create database command. Passes on
   key/value arguments it does not understand to postgresql-script.

   Example: (create-database \"my-database\" :db-parameters [:encoding \"'LATIN1'\"])"
  [request db-name & rest]
  (let [{:keys [db-parameters] :as options} rest
	db-parameters-str (str/join " " (map as-str db-parameters))]
    (stevedore/script (chain-or ~(apply postgresql-script
					request
					(format "CREATE DATABASE %s %s;" db-name db-parameters-str)
					rest)
				true))))

(defscript database-exists? [as-user db-name])
(stevedore/defimpl database-exists? :default [as-user db-name]
  (sudo "-u" ~as-user psql "-t -c"
	~(format "\"select count(1) from pg_database where datname='%s'\""
		 db-name)))

(defn ensure-database-exists
  [request db-name & rest]
  (let [{:keys [as-user] :or {as-user "postgres"}} rest]
    (-> request
	(resource-when/resource-when
	 (= @(database-exists? as-user db-name) "0")
	 (apply-> create-database db-name rest)))))