content/documentation/extensions/mod_hjson.adoc

:jbake-type: page
:jbake-status: published

= Apache Tamaya - Extension: HJSON Format

toc::[]


[[HJSON]]
== Tamaya HJSON (Extension Module)
Tamaya _HJSON_ is an extension module. Refer also to the link:../extensions.html[extensions documentation] for further details.

=== What functionality does this module provide?

Tamaya _HJSON_ provides support for reading configuration in HJSON, a JSP similar format better
suited for humans:

[source, hjson]
-----------------------------------------------
{
  a : A
  b : {
    o : O
    p : P
  }
  c : C
}
-----------------------------------------------

Hereby the hierarchical structure of the JSON document will be mapped to a
corresponding `PropertyValue` tree structure. This structure can be mapped
to flat key-value pairs of type `String`, e.g. the above will be mapped to

[source, properties]
-----------------------------------------------
a=A
b.o=O
b.p=P
c=C
-----------------------------------------------

This extension implements the SPI defined by the +tamaya.formats+ extension module.


=== Compatibility

The module is based on Java 8.


=== Installation

To use the HJSON extension module you only must add the corresponding dependency to your project:

[source, xml, subs=attributes+]
-----------------------------------------------
<dependency>
  <groupId>org.apache.tamaya.ext</groupId>
  <artifactId>tamaya-hjson</artifactId>
  <version>{tamaya_version}</version>
</dependency>
-----------------------------------------------

This extension also transitively requires the +tamaya.formats+ module.


=== Reading configuration in HJSON

For reading HJSON based configuration most easily a +HJSONFormat+ can be
used:

[source, java]
-----------------------------------------------
ConfigurationData dataRead = ConfigurationFormats.getInstance().readConfig(
    getClassLoader().getResource("myFileConfig.json"), new HJSONFormat()));
-----------------------------------------------

Or, if you are fine with the _default_ mapping you can directly create a
+PropertySource+ using the _formats_ API (this works since this module
registers the _json_ format automatically using the `ServiceContext`):

[source, java]
-----------------------------------------------
PropertySource ps = ConfigurationFormats.getInstance().createPropertySource(
    getClassLoader().getResource("myFileConfig.hjson"));
-----------------------------------------------