JSON accessor functions for PostgreSQL

Extension provides stored functions for accessing JSON fields by keys and converting JSON arrays.

This project contains PostgreSQL extension json_accessors with stored functions. Extension is native and writen in C on top of modified cJSON library (very old version).

Extension supports PostgreSQL 9.1 through 17.

PostgreSQL have had no JSON support until version 9.2, which introduced some support. These 9.2 functions won't help with indexing JSON data.

JSON parsing functions may be written using PL/V8 module, this article has an example of PL/V8 usage. This project provides accessor functions for JSON without using PL/V8.

Usage

Please consult with doc/json_accessors.md for a function and operator reference.

On PGXN please click on extension from Extensions section to view reference.

Installing extension

To use an extension one must be built, installed into PostgreSQL directory and registered in a database.

Building extension

Using PGXN network

The easisest method to get and install an extension from PGXN network. PGXN client downloads and builds the extension.

pgxn --pg_config <postgresql_install_dir>/bin/pg_config install json_accessors

PGXN client itself is available at github and can be installed with your favourite method, i.e. easy_install pgxnclient.

Using PGXS makefiles

C extension are best built and installed using PGXS. PGXS ensures that make is performed with needed compiler and flags. You only need GNU make and a compiler to build an extension on an almost any UNIX platform (Linux, Solaris, OS X).

Compilation:

gmake PG_CONFIG=<postgresql_install_dir>/bin/pg_config

Installation (as superuser):

gmake PG_CONFIG=<postgresql_install_dir>/bin/pg_config install

PostgreSQL server must be restarted.

To uninstall extension completely you may use this command (as superuser):

gmake PG_CONFIG=<postgresql_install_dir>/bin/pg_config uninstall

Project contains SQL tests that can be launched on PostgreSQL with installed extension. Tests are performed on a dynamically created database with a specified user (with the appropriated permissions - create database, for example):

gmake PG_CONFIG=<postgresql_install_dir>/bin/pg_config install
gmake PG_CONFIG=<postgresql_install_dir>/bin/pg_config PGUSER=postgres installcheck

Manually

Use this method if you have a precompiled extension and do not want to install this with help of PGXS. Or maybe you just do not have GNU make on a production server. Or if you use Windows (use MSVC 2008 for Postgres 9.1 and MSVC 2010 for Postgres 9.2).

Copy library to the PostgreSQL library directory:

cp json_accessors.so `<postgresql_install_dir>/bin/pg_config --pkglibdir` 

Copy control file to the extension directory:

cp json_accessors.control `<postgresql_install_dir>/bin/pg_config --sharedir`/extension

Copy SQL prototypes file to the extension directory:

cp json_accessors--<version>.sql `<postgresql_install_dir>/bin/pg_config --sharedir`/extension

To uninstall extension just remove files you copied before.

Creating extension in a database

Extension must be previously installed to a PostgreSQL directory.

Extension is created in a particular database (as superuser):

create extension json_accessors;

It creates all the functions, operators and other stuff from extension. Note that you must restart a server if a previous library was already installed at the same place. In other words, always restart to be sure.

To drop an extension use:

drop extension json_accessors cascade;

License information

You can use any code from this project under the terms of PostgreSQL License.

Please consult with the COPYING for license information.