Jackson API Config

Jackson provides many ways to work with JSON/POJO objects converting to/from them.

whinstone-couchdb use Jackson API library to save the JSON format into couchdb database and convert the JSON values to POJO objects.

Sample of src/main/resources/repository-config.xml file:

<repository name="users">
  <description>My couchdb database</description>
  <jndi-data-source>jdbc/dsUsers</jndi-data-source>
  <properties>
    <property name="jackson.WRITE_DATES_AS_TIMESTAMPS" value="true"/>
  </properties>
</repository>

All properties started with jackson.* will be configured to work with singleton instance of ObjectMapper.

<repository name="users">
  ...
  <properties>
    <property name="jackson.module.ParameterNamesModule" value="true"/>
    <property name="jackson.module.Jdk8Module" value="true"/>
    <property name="jackson.module.JavaTimeModule" value="true"/>
  </properties>
</repository>

Design Documents

Views

In CouchDB, design documents provide the main interface for building a CouchDB application. The design document defines the views used to extract information from CouchDB through one or more views.

Automatically whinstone-couchdb update the views to database when a new instance of Repository is created. That feature helps keep the view update accordingly the deployed version of application. Default behavior is false if you want keep the views updated define the property to true:

<property name="jkniv.couchdb.update_views" value="true"/>

The viewer code is kept together with the SQL code into XML file under a specific prefix package name _design. So this views code will be update into CouchDB.

<package name="_design/docs">
  <select id="map#natio-combo">
    <description>generate unique values of nationality</description>
    function (doc) {
      if(doc.nationality) {
        emit(doc.nationality, 1);
      }
    }
  </select>
  <select id="reduce#natio-combo">
  <description>Count total of nationalities</description>
    function(keys, values) {
      return sum(values);
    }
  </select>
</package>

There are 2 types of function on CouchDB to map it for whinstone use the prefixes map# and reduce#:

• For map function the select name must start with map#
• For reduce function the select name must start with reduce#

Indexes

Mango is a declarative JSON querying language for CouchDB databases. Mango wraps several index types, starting with the Primary Index out-of-the-box. Mango indexes, with index type json, are built using MapReduce Views.

Automatically whinstone-couchdb drop and create the indexes to database when a new instance of Repository is created. That feature helps keep the indesx update accordingly the deployed version of application. Default behavior is false if you want keep the indexes updated define the property to true:

<property name="jkniv.couchdb.update_indexes" value="true"/>

Example:

<package name="_design/indexes">
  <select id="index#auto-create-foo-index">
  {
     "index": {
        "fields": [
           "foo"
        ]
     },
     "type": "json",
     "name": "auto-create-foo-index",
     "ddoc": "auto-create-foo-index"
  }
  </select>
</package>

Start a package name with _design is mandatory to separate the indexes from Mango Queries and the id must start with index#

The ddoc value must have the same suffix name from id property (this example is auto-create-foo-index ). This way whinstone-couchdb can drop the actual index and create a new index.