Getting_started_with_Objective Caml

Getting started with OCaml and the CouchDB API

For making the HTTP calls required by the RESTful API, it's hard to beat Gerd Stolpmann's Http_client.Convenience module (see http://docs.camlcity.org/docs/godipkg/3.11/godi-ocamlnet/doc/godi-ocamlnet/html/Http_client.Convenience.html ), shipped with the ocamlnet-2 library (see http://docs.camlcity.org/docs/godipkg/3.11/godi-ocamlnet ). The examples below assume your database is running on the localhost, port 5984--and that your database is named "mydatabase". Naturally, you're encouraged to change these to fit your specific needs.

Creating a Database

let result = 
  let server_url = "http://localhost:5984" in 
    let db_name = "mydatabase" in 
      Http_client.Convenience.http_put (server_url ^ "/" ^ db_name) "";;

print_endline result

Deleting a Database

let result = 
  let server_url = "http://localhost:5984" in 
    let db_name = "mydatabase" in 
      Http_client.Convenience.http_delete (server_url ^ "/" ^ db_name);;

print_endline result

Creating a Document

let result = 
  let url_doc = "http://localhost:5984/mydatabase/newdoc" in 
    let my_doc_json = "{ \"subject\":\"Plankton\", \"author\":\"Rusty\"," ^
                      "\"body\":\"I decided today I like plankton and OCaml equally well.\" }" in
      Http_client.Convenience.http_put url_doc my_doc_json;;

print_endline result

Retrieving a Document

The example below shows a bit more sophistication, illustrating how to use the json-wheel library (located at http://martin.jambon.free.fr/json-wheel.html).

type json doc = < subject:string; author:string; body:string > 
let url_doc = "http://localhost:5984/mydatabase/newdoc"
let get url =
  doc_of_json
    (Json_io.json_of_string
       (Http_client.Convenience.http_get (url)))

let my_doc = (get url_doc)
let _= print_string ("Author: "  ^ my_doc#author  ^ "\n" ^ 
                     "Subject: " ^ my_doc#subject ^ "\n" ^ 
                     "Body: "    ^ my_doc#body    ^ "\n")


$ ./retrieve_doc

Author: Rusty
Subject: Plankton
Body: I decided today I like plankton and OCaml equally well.

Note: These examples can be compiled with the following:

ocamlfind ocamlopt -o dest-file -linkpkg -package json-static,netclient -syntax camlp4o source-file.ml