[[freemarker-component]]
= Freemarker Component
:page-source: components/camel-freemarker/src/main/docs/freemarker-component.adoc

*Available as of Camel version 2.10*


The *freemarker:* component allows for processing a message using a
http://freemarker.org/[FreeMarker] template. This can be ideal when
using Templating to generate responses for
requests.

Maven users will need to add the following dependency to their `pom.xml`
for this component:

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

== URI format

[source,java]
---------------------------------
freemarker:templateName[?options]
---------------------------------

Where *templateName* is the classpath-local URI of the template to
invoke; or the complete URL of the remote template (eg:
`\file://folder/myfile.ftl`).

You can append query options to the URI in the following format,
`?option=value&option=value&...`

== Options




// component options: START
The Freemarker component supports 4 options, which are listed below.



[width="100%",cols="2,5,^1,2",options="header"]
|===
| Name | Description | Default | Type
| *configuration* (advanced) | To use an existing freemarker.template.Configuration instance as the configuration. |  | Configuration
| *allowTemplateFrom Header* (producer) | Whether to allow to use resource template from header or not (default false). Enabling this allows to specify dynamic templates via message header. However this can be seen as a potential security vulnerability if the header is coming from a malicious user, so use this with care. | false | boolean
| *allowContextMapAll* (producer) | Sets whether the context map should allow access to all details. By default only the message body and headers can be accessed. This option can be enabled for full access to the current Exchange and CamelContext. Doing so impose a potential security risk as this opens access to the full power of CamelContext API. | false | boolean
| *resolveProperty Placeholders* (advanced) | Whether the component should resolve property placeholders on itself when starting. Only properties which are of String type can use property placeholders. | true | boolean
|===
// component options: END





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

----
freemarker:resourceUri
----

with the following path and query parameters:

=== Path Parameters (1 parameters):


[width="100%",cols="2,5,^1,2",options="header"]
|===
| Name | Description | Default | Type
| *resourceUri* | *Required* Path to the resource. You can prefix with: classpath, file, http, ref, or bean. classpath, file and http loads the resource using these protocols (classpath is default). ref will lookup the resource in the registry. bean will call a method on a bean to be used as the resource. For bean you can specify the method name after dot, eg bean:myBean.myMethod. |  | String
|===


=== Query Parameters (7 parameters):


[width="100%",cols="2,5,^1,2",options="header"]
|===
| Name | Description | Default | Type
| *allowContextMapAll* (producer) | Sets whether the context map should allow access to all details. By default only the message body and headers can be accessed. This option can be enabled for full access to the current Exchange and CamelContext. Doing so impose a potential security risk as this opens access to the full power of CamelContext API. | false | boolean
| *allowTemplateFromHeader* (producer) | Whether to allow to use resource template from header or not (default false). Enabling this allows to specify dynamic templates via message header. However this can be seen as a potential security vulnerability if the header is coming from a malicious user, so use this with care. | false | boolean
| *configuration* (producer) | Sets the Freemarker configuration to use |  | Configuration
| *contentCache* (producer) | Sets whether to use resource content cache or not | false | boolean
| *encoding* (producer) | Sets the encoding to be used for loading the template file. |  | String
| *templateUpdateDelay* (producer) | Number of seconds the loaded template resource will remain in the cache. |  | int
| *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-freemarker-starter</artifactId>
  <version>x.x.x</version>
  <!-- use the same version as your Camel core version -->
</dependency>
----


The component supports 5 options, which are listed below.



[width="100%",cols="2,5,^1,2",options="header"]
|===
| Name | Description | Default | Type
| *camel.component.freemarker.allow-context-map-all* | Sets whether the context map should allow access to all details. By default only the message body and headers can be accessed. This option can be enabled for full access to the current Exchange and CamelContext. Doing so impose a potential security risk as this opens access to the full power of CamelContext API. | false | Boolean
| *camel.component.freemarker.allow-template-from-header* | Whether to allow to use resource template from header or not (default false). Enabling this allows to specify dynamic templates via message header. However this can be seen as a potential security vulnerability if the header is coming from a malicious user, so use this with care. | false | Boolean
| *camel.component.freemarker.configuration* | To use an existing freemarker.template.Configuration instance as the configuration. The option is a freemarker.template.Configuration type. |  | String
| *camel.component.freemarker.enabled* | Enable freemarker component | true | Boolean
| *camel.component.freemarker.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




== Headers

Headers set during the FreeMarker evaluation are returned to the message
and added as headers. This provides a mechanism for the FreeMarker
component to return values to the Message.

An example: Set the header value of `fruit` in the FreeMarker template:

[source,java]
--------------------------------------
${request.setHeader('fruit', 'Apple')}
--------------------------------------

The header, `fruit`, is now accessible from the `message.out.headers`.

== FreeMarker Context

Camel will provide exchange information in the FreeMarker context (just
a `Map`). The `Exchange` is transferred as:

[width="100%",cols="50%,50%",options="header",]
|=======================================================================
|key |value

|`exchange` |The `Exchange` itself.

|`exchange.properties` |The `Exchange` properties.

|`headers` |The headers of the In message.

|`camelContext` |The Camel Context.

|`request` |The In message.

|`body` |The In message body.

|`response` |The Out message (only for InOut message exchange pattern).
|=======================================================================

From Camel 2.14, you can setup your custom FreeMarker context in the
message header with the key "*CamelFreemarkerDataModel*" just like this

[source,java]
--------------------------------------------------------------------
Map<String, Object> variableMap = new HashMap<String, Object>();
variableMap.put("headers", headersMap);
variableMap.put("body", "Monday");
variableMap.put("exchange", exchange);
exchange.getIn().setHeader("CamelFreemarkerDataModel", variableMap);
--------------------------------------------------------------------

== Hot reloading

The FreeMarker template resource is by default *not* hot reloadable for
both file and classpath resources (expanded jar). If you set
`contentCache=false`, then Camel will not cache the resource and hot
reloading is thus enabled. This scenario can be used in development.

== Dynamic templates

Camel provides two headers by which you can define a different resource
location for a template or the template content itself. If any of these
headers is set then Camel uses this over the endpoint configured
resource. This allows you to provide a dynamic template at runtime.

[width="100%",cols="10%,10%,10%,70%",options="header",]
|=======================================================================
|Header |Type |Description |Support Version

|FreemarkerConstants.FREEMARKER_RESOURCE |org.springframework.core.io.Resource |The template resource | <= 2.1

|FreemarkerConstants.FREEMARKER_RESOURCE_URI |String |A URI for the template resource to use instead of the endpoint
configured. | >= 2.1

|FreemarkerConstants.FREEMARKER_TEMPLATE |String |The template to use instead of the endpoint configured. | >= 2.1
|=======================================================================

== Samples

For example you could use something like:

[source,java]
-------------------------------------------
from("activemq:My.Queue").
  to("freemarker:com/acme/MyResponse.ftl");
-------------------------------------------

To use a FreeMarker template to formulate a response for a message for
InOut message exchanges (where there is a `JMSReplyTo` header).

If you want to use InOnly and consume the message and send it to another
destination you could use:

[source,java]
-------------------------------------------
from("activemq:My.Queue").
  to("freemarker:com/acme/MyResponse.ftl").
  to("activemq:Another.Queue");
-------------------------------------------

And to disable the content cache, e.g. for development usage where the
`.ftl` template should be hot reloaded:

[source,java]
--------------------------------------------------------------
from("activemq:My.Queue").
  to("freemarker:com/acme/MyResponse.ftl?contentCache=false").
  to("activemq:Another.Queue");
--------------------------------------------------------------

And a file-based resource:

[source,java]
---------------------------------------------------------------------
from("activemq:My.Queue").
  to("freemarker:file://myfolder/MyResponse.ftl?contentCache=false").
  to("activemq:Another.Queue");
---------------------------------------------------------------------

In *Camel 2.1* it's possible to specify what template the component
should use dynamically via a header, so for example:

[source,java]
---------------------------------------------------------------------------------------------
from("direct:in").
  setHeader(FreemarkerConstants.FREEMARKER_RESOURCE_URI).constant("path/to/my/template.ftl").
  to("freemarker:dummy");
---------------------------------------------------------------------------------------------

== The Email Sample

In this sample we want to use FreeMarker templating for an order
confirmation email. The email template is laid out in FreeMarker as:

[source,java]
----------------------------------------------
Dear ${headers.lastName}, ${headers.firstName}

Thanks for the order of ${headers.item}.

Regards Camel Riders Bookstore
${body}
----------------------------------------------

And the java code:
