datafly

Datafly is a lightweight database library for Common Lisp.

Quickstart

Datafly provides 3 functions which wrap CL-DBI — retrieve-one, retrieve-all and execute.

They take a SxQL statement.

(use-package :sxql)

(connect-toplevel :sqlite3 :database-name #P"myapp.db")

(retrieve-one
  (select :*
    (from :user)
    (where (:= :name "nitro_idiot"))))
;=> (:ID 1 :NAME "nitro_idiot" :EMAIL "nitro_idiot@example.com" :REGISTERED-AT "2014-04-14T19:20:13")

(retrieve-all
  (select :*
    (from :user)))
;=> ((:ID 1 :NAME "nitro_idiot" :EMAIL "nitro_idiot@example.com" :REGISTERED-AT "2014-04-14T19:20:13")
;    (:ID 2 :NAME "m2ym" :EMAIL "m2ym@example.com" :REGISTERED-AT "2014-04-15T01:03:42"))

(execute
 (insert-into :tweet
   (set= :id 1
         :user_id 1
         :body "Hi."
         :created_at (princ-to-string *now*))))

If you specify :as option with a class name to retrieval functions, they create instances of the class for each rows.

(defstruct user
  id
  name
  email
  registered-at)

(retrieve-one
  (select :*
    (from :user)
    (where (:= :name "nitro_idiot")))
  :as 'user)
;=> #S(USER :ID 1 :NAME "nitro_idiot" :EMAIL "nitro_idiot@example.com" :REGISTERED-AT "2014-04-14T19:20:13")

(retrieve-all
  (select :*
    (from :user))
  :as 'user)
;=> (#S(USER :ID 1 :NAME "nitro_idiot" :EMAIL "nitro_idiot@example.com" :REGISTERED-AT "2014-04-14T19:20:13")
;    #S(USER :ID 2 :NAME "m2ym" :EMAIL "m2ym@example.com" :REGISTERED-AT "2014-04-15T01:03:42"))

The structure doesn't require having slots same as an existing table's in a database. It is acceptable even if the names are different. This might be convenient when you'd like to treat a JOINed table result as a structure object.

Model Definitions

Datafly provides a macro defmodel which defines a flavored structure class.

(defmodel (user (:inflate registered-at #'datetime-to-timestamp))
  id
  name
  email
  registered-at)


;; Same as the above.
(syntax:use-syntax :annot)

@model
(defstruct (user (:inflate registered-at #'datetime-to-timestamp))
  id
  name
  email
  registered-at)

(:inflate <columns> <inflation-function>) options mean inflation-function will be applied to each <columns> when creating an instance.

(defvar *user*
  (retrieve-one
    (select :*
      (from :user)
      (where (:= :name "nitro_idiot")))
    :as 'user))

;; Returns a local-time:timestamp.
(user-registered-at *user*)
;=> @2014-04-15T04:20:13.000000+09:00

defmodel also allows :has-a and :has-many options.

(use-package :sxql)

(defmodel (user (:inflate registered-at #'datetime-to-timestamp)
                (:has-a config (where (:= :user_id id)))
                (:has-many (tweets tweet)
                 (select :*
                   (from :tweet)
                   (where (:= :user_id id))
                   (order-by (:desc :created_at)))))
  id
  name
  email
  registered-at)

(defvar *user*
  (retrieve-one
    (select :*
      (from :user)
      (where (:= :name "nitro_idiot")))
    :as 'user))

(user-config *user*)
;=> #S(CONFIG :ID 4 :USER-ID 1 :TIMEZONE "JST" :COUNTRY "jp" :LANGUAGE "ja")

(user-tweets *user*)
;=> (#S(TWEET :ID 2 :USER-ID 1 :BODY "Is it working?" :CREATED-AT @2014-04-16T11:02:31.000000+09:00)
;    #S(TWEET :ID 1 :USER-ID 1 :BODY "Hi." :CREATED-AT @2014-04-15T18:58:20.000000+09:00))

Provided inflation functions

• tinyint-to-boolean
• datetime-to-timestamp
• unixtime-to-timestamp
• string-to-keyword
• octet-vector-to-string

Tips: Getting Association List or Hash Table for each rows

retrieve-one and retrieve-all return row(s) as a property list or a list of property lists by default.

If you'd like they were other types, for example "Association List" or "Hash Table", you can do it by passing :as parameter.

(retrieve-one
  (select :*
    (from :user)
    (where (:= :name "nitro_idiot")))
  :as 'trivial-types:association-list)
;=> ((:ID . 1) (:NAME . "nitro_idiot") (:EMAIL . "nitro_idiot@example.com") (:REGISTERED-AT . "2014-04-14T19:20:13"))

(retrieve-one
  (select :*
    (from :user)
    (where (:= :name "nitro_idiot")))
  :as 'hash-table)
;=> #<HASH-TABLE :TEST EQL :COUNT 4 {1007AE3CD3}>

If no :as parameter is specified, *default-row-type* will be used.

(let ((*default-row-type* 'hash-table))
  (retrieve-all
    (select :*
      (from :user))))
;=> (#<HASH-TABLE :TEST EQL :COUNT 4 {100815FA03}> #<HASH-TABLE :TEST EQL :COUNT 4 {100815FE43}>)

See Also

• SxQL
• CL-DBI
• cl-annot, CL-SYNTAX
• function-cache

Author

• Eitaro Fukamachi (e.arrows@gmail.com)

Copyright

Copyright (c) 2014 Eitaro Fukamachi (e.arrows@gmail.com)

License

Licensed under the BSD 3-Clause License.