StringTemplate

String Template

The string-template: component allows you to process a message using a String 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:

xml

<dependency> <groupId>org.apache.camel</groupId> <artifactId>camel-stringtemplate</artifactId> <version>x.x.x</version>  </dependency>

URI Format

string-template:templateName[?options]

Where templateName is the classpath-local URI of the template to invoke; or the complete URL of the remote template.

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

Options

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Option	Default	Description
`contentCache`	`false`	Cache for the resource content when its loaded. Note: as of Camel 2.9 cached resource content can be cleared via JMX using the endpoint's `clearContentCache` operation.
`delimiterStart`	`null`	From Camel 2.11.1: configuring the variable start delimiter
`delimiterStop`	`null`	From Camel 2.11.1: configuring the variable end delimiter

Headers

Camel will store a reference to the resource in the message header with key, org.apache.camel.stringtemplate.resource. The Resource is an org.springframework.core.io.Resource object.

Hot-Reloading

The string template resource is by default hot-reloadable for both file and classpath resources (expanded jar). If you set contentCache=true, Camel will load the resource just once, disabling hot-reloading. This scenario can be used in production when the resource never changes.

StringTemplate Attributes

Camel will provide exchange information as attributes (just a java.util.Map) to the string template. The Exchange is transferred as:

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Key	Value
`exchange`	The Exchange itself.
`headers`	The headers of the `IN` message.
`camelContext`	The Camel Context.
`request`	The `IN` message.
`in`	The `IN` message.
`body`	The `IN` message body.
`out`	The `OUT` message (only for `InOut` message exchange pattern).
`response`	The `OUT` message (only for `InOut` message exchange pattern).

From Camel 2.14: you can define the custom context map by setting the message header CamelStringTemplateVariableMap, as shown below:

java

Map<String, Object> variableMap = new HashMap<String, Object>(); Map<String, Object> headersMap = new HashMap<String, Object>(); headersMap.put("name", "Willem"); variableMap.put("headers", headersMap); variableMap.put("body", "Monday"); variableMap.put("exchange", exchange); exchange.getIn().setHeader("CamelStringTemplateVariableMap", variableMap);

Samples

For example you could use a string template as follows in order to formulate a response to a message:

from("activemq:My.Queue") .to("string-template:com/acme/MyResponse.tm");

The Email Sample

In this sample we want to use a string template to send an order confirmation email. The email template is laid out in StringTemplate as:
This example works for camel 2.11.0. If your camel version is less than 2.11.0, the variables should be started and ended with $.

Dear <headers.lastName>, <headers.firstName> Thanks for the order of <headers.item>. Regards Camel Riders Bookstore <body>

And the java code is as follows:{snippet:id=e1|lang=java|url=camel/trunk/components/camel-stringtemplate/src/test/java/org/apache/camel/component/stringtemplate/StringTemplateLetterTest.java}Endpoint See Also

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