[[dozer-component]]
== Dozer Component

*Available as of Camel version 2.15*

The *dozer:* component provides the ability to map between Java beans
using the http://camel.apache.org/dozer-type-conversion.html[Dozer]
mapping framework since *Camel 2.15.0*.  Camel also supports the ability
to trigger Dozer mappings
http://camel.apache.org/dozer-type-conversion.html[as a type converter].
 The primary differences between using a Dozer endpoint and a Dozer
converter are:

* The ability to manage Dozer mapping configuration on a per-endpoint
basis vs. global configuration via the converter registry.
* A Dozer endpoint can be configured to marshal/unmarshal input and
output data using Camel data formats to support a single, any-to-any
transformation endpoint
* The Dozer component allows for fine-grained integration and extension
of Dozer to support additional functionality (e.g. mapping literal
values, using expressions for mappings, etc.).

In order to use the Dozer component, Maven users will need to add the
following dependency to their `pom.xml`:

[source,xml]
------------------------------------------------------------
<dependency>
    <groupId>org.apache.camel</groupId>
    <artifactId>camel-dozer</artifactId>
    <version>x.x.x</version>
    <!-- use the same version as your Camel core version -->
</dependency>
------------------------------------------------------------

### URI format

The Dozer component only supports producer endpoints.

[source,java]
--------------------------
dozer:endpointId[?options]
--------------------------

Where *endpointId* is a name used to uniquely identify the Dozer
endpoint configuration. 

An example Dozer endpoint URI:

[source,java]
---------------------------------------------------------------------------------------
from("direct:orderInput").
  to("dozer:transformOrder?mappingFile=orderMapping.xml&targetModel=example.XYZOrder").
  to("direct:orderOutput");
---------------------------------------------------------------------------------------

### Options

// component options: START
The Dozer component has no options.
// component options: END

// endpoint options: START
The Dozer endpoint is configured using URI syntax:

----
dozer:name
----

with the following path and query parameters:

==== Path Parameters (1 parameters):


[width="100%",cols="2,5,^1,2",options="header"]
|===
| Name | Description | Default | Type
| *name* | *Required* A human readable name of the mapping. |  | String
|===


==== Query Parameters (7 parameters):


[width="100%",cols="2,5,^1,2",options="header"]
|===
| Name | Description | Default | Type
| *mappingConfiguration* (producer) | The name of a DozerBeanMapperConfiguration bean in the Camel registry which should be used for configuring the Dozer mapping. This is an alternative to the mappingFile option that can be used for fine-grained control over how Dozer is configured. Remember to use a # prefix in the value to indicate that the bean is in the Camel registry (e.g. #myDozerConfig). |  | DozerBeanMapper Configuration
| *mappingFile* (producer) | The location of a Dozer configuration file. The file is loaded from the classpath by default, but you can use file:, classpath:, or http: to load the configuration from a specific location. | dozerBeanMapping.xml | String
| *marshalId* (producer) | The id of a dataFormat defined within the Camel Context to use for marshalling the mapping output to a non-Java type. |  | String
| *sourceModel* (producer) | Fully-qualified class name for the source type used in the mapping. If specified, the input to the mapping is converted to the specified type before being mapped with Dozer. |  | String
| *targetModel* (producer) | *Required* Fully-qualified class name for the target type used in the mapping. |  | String
| *unmarshalId* (producer) | The id of a dataFormat defined within the Camel Context to use for unmarshalling the mapping input from a non-Java type. |  | String
| *synchronous* (advanced) | Sets whether synchronous processing should be strictly used, or Camel is allowed to use asynchronous processing (if supported). | false | boolean
|===
// endpoint options: END
// spring-boot-auto-configure options: START
=== Spring Boot Auto-Configuration

When using Spring Boot make sure to use the following Maven dependency to have support for auto configuration:

[source,xml]
----
<dependency>
  <groupId>org.apache.camel</groupId>
  <artifactId>camel-dozer-starter</artifactId>
  <version>x.x.x</version>
  <!-- use the same version as your Camel core version -->
</dependency>
----


The component supports 2 options, which are listed below.



[width="100%",cols="2,5,^1,2",options="header"]
|===
| Name | Description | Default | Type
| *camel.component.dozer.enabled* | Enable dozer component | true | Boolean
| *camel.component.dozer.resolve-property-placeholders* | Whether the component should resolve property placeholders on itself when starting. Only properties which are of String type can use property placeholders. | true | Boolean
|===
// spring-boot-auto-configure options: END


### Using Data Formats with Dozer

Dozer does not support non-Java sources and targets for mappings, so it
cannot, for example, map an XML document to a Java object on its own.
 Luckily, Camel has extensive support for marshalling between Java and a
wide variety of formats using
http://camel.apache.org/data-format.html[data formats].  The Dozer
component takes advantage of this support by allowing you to specify
that input and output data should be passed through a data format prior
to processing via Dozer.  You can always do this on your own outside the
call to Dozer, but supporting it directly in the Dozer component allows
you to use a single endpoints to configure any-to-any transformation
within Camel.

As an example, let's say you wanted to map between an XML data structure
and a JSON data structure using the Dozer component.  If you had the
following data formats defined in a Camel Context:

[source,xml]
-----------------------------------------------
<dataFormats>
  <json library="Jackson" id="myjson"/>
  <jaxb contextPath="org.example" id="myjaxb"/>
</dataFormats>
-----------------------------------------------

You could then configure a Dozer endpoint to unmarshal the input XML
using a JAXB data format and marshal the mapping output using Jackson.

[source,xml]
----------------------------------------------------------------------------------------------------------
<endpoint uri="dozer:xml2json?marshalId=myjson&amp;unmarshalId=myjaxb&amp;targetModel=org.example.Order"/>
----------------------------------------------------------------------------------------------------------

### Configuring Dozer

All Dozer endpoints require a Dozer mapping configuration file which
defines mappings between source and target objects.  The component will
default to a location of META-INF/dozerBeanMapping.xml if the
mappingFile or mappingConfiguration options are not specified on an
endpoint.  If you need to supply multiple mapping configuration files
for a single endpoint or specify additional configuration options (e.g.
event listeners, custom converters, etc.), then you can use an instance
of `org.apache.camel.converter.dozer.DozerBeanMapperConfiguration`.

[source,xml]
------------------------------------------------------------------------------------------
<bean id="mapper" class="org.apache.camel.converter.dozer.DozerBeanMapperConfiguration">  
  <property name="mappingFiles">
    <list>
      <value>mapping1.xml</value>
      <value>mapping2.xml</value>
    </list>
  </property>
</bean>
------------------------------------------------------------------------------------------

### Mapping Extensions

The Dozer component implements a number of extensions to the Dozer
mapping framework as custom converters.  These converters implement
mapping functions that are not supported directly by Dozer itself.

#### Variable Mappings

Variable mappings allow you to map the value of a variable definition
within a Dozer configuration into a target field instead of using the
value of a source field.  This is equivalent to constant mapping in
other mapping frameworks, where can you assign a literal value to a
target field.  To use a variable mapping, simply define a variable
within your mapping configuration and then map from the VariableMapper
class into your target field of choice:

[source,xml]
--------------------------------------------------------------------------------------------------------
<mappings xmlns="http://dozermapper.github.io/schema/bean-mapping"
          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
          xsi:schemaLocation="http://dozermapper.github.io/schema/bean-mapping http://dozermapper.github.io/schema/bean-mapping.xsd">
  <configuration>
    <variables>
      <variable name="CUST_ID">ACME-SALES</variable>
    </variables>
  </configuration>
  <mapping>
    <class-a>org.apache.camel.component.dozer.VariableMapper</class-a>
    <class-b>org.example.Order</class-b>
    <field custom-converter-id="_variableMapping" custom-converter-param="${CUST_ID}">
      <a>literal</a>
      <b>custId</b>
    </field>
  </mapping>
</mappings>
--------------------------------------------------------------------------------------------------------

#### Custom Mappings

Custom mappings allow you to define your own logic for how a source
field is mapped to a target field.  They are similar in function to
Dozer customer converters, with two notable differences:

* You can have multiple converter methods in a single class with custom
mappings.
* There is no requirement to implement a Dozer-specific interface with
custom mappings.

A custom mapping is declared by using the built-in '_customMapping'
converter in your mapping configuration.  The parameter to this
converter has the following syntax:

[source,shell]
--------------------------
[class-name][,method-name]
--------------------------

Method name is optional - the Dozer component will search for a method
that matches the input and output types required for a mapping.  An
example custom mapping and configuration are provided below.

[source,java]
--------------------------------------------------
public class CustomMapper {
    // All customer ids must be wrapped in "[ ]"
    public Object mapCustomer(String customerId) {
        return "[" + customerId + "]";
    }
} 
--------------------------------------------------

[source,xml]
--------------------------------------------------------------------------------------------------------
<mappings xmlns="http://dozermapper.github.io/schema/bean-mapping"
          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
          xsi:schemaLocation="http://dozermapper.github.io/schema/bean-mapping http://dozermapper.github.io/schema/bean-mapping.xsd">
  <mapping>
    <class-a>org.example.A</class-a>
    <class-b>org.example.B</class-b>
    <field custom-converter-id="_customMapping" 
        custom-converter-param="org.example.CustomMapper,mapCustomer">
      <a>header.customerNum</a>
      <b>custId</b>
    </field>
  </mapping>
</mappings>
--------------------------------------------------------------------------------------------------------

#### Expression Mappings

Expression mappings allow you to use the powerful
http://camel.apache.org/languages.html[language] capabilities of Camel
to evaluate an expression and assign the result to a target field in a
mapping.  Any language that Camel supports can be used in an expression
mapping.  Basic examples of expressions include the ability to map a
Camel message header or exchange property to a target field or to
concatenate multiple source fields into a target field.  The syntax of a
mapping expression is:

[source,shell]
----------------------- 
[language]:[expression]
-----------------------

An example of mapping a message header into a target field:

[source,xml]
--------------------------------------------------------------------------------------------------------------
<mappings xmlns="http://dozermapper.github.io/schema/bean-mapping"
          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
          xsi:schemaLocation="http://dozermapper.github.io/schema/bean-mapping http://dozermapper.github.io/schema/bean-mapping.xsd">
  <mapping>
    <class-a>org.apache.camel.component.dozer.ExpressionMapper</class-a>
    <class-b>org.example.B</class-b>
    <field custom-converter-id="_expressionMapping" custom-converter-param="simple:\${header.customerNumber}">
      <a>expression</a>
      <b>custId</b>
    </field>
  </mapping>
</mappings>
--------------------------------------------------------------------------------------------------------------

Note that any properties within your expression must be escaped with "\"
to prevent an error when Dozer attempts to resolve variable values
defined using the EL.
