String Template

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

The String Template component supports 4 options, which are listed below.

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
lazyStartProducer (producer)	Whether the producer should be started lazy (on the first message). By starting lazy you can use this to allow CamelContext and routes to startup in situations where a producer may otherwise fail during starting and cause the route to fail being started. By deferring this startup to be lazy then the startup failure can be handled during routing messages via Camel’s routing error handlers. Beware that when the first message is processed then creating and starting the producer may take a little time and prolong the total processing time of the processing.	false	boolean
autowiredEnabled (advanced)	Whether autowiring is enabled. This is used for automatic autowiring options (the option must be marked as autowired) by looking up in the registry to find if there is a single instance of matching type, which then gets configured on the component. This can be used for automatic configuring JDBC data sources, JMS connection factories, AWS Clients, etc.	true	boolean

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

lazyStartProducer (producer)

Whether the producer should be started lazy (on the first message). By starting lazy you can use this to allow CamelContext and routes to startup in situations where a producer may otherwise fail during starting and cause the route to fail being started. By deferring this startup to be lazy then the startup failure can be handled during routing messages via Camel’s routing error handlers. Beware that when the first message is processed then creating and starting the producer may take a little time and prolong the total processing time of the processing.

false

boolean

autowiredEnabled (advanced)

Whether autowiring is enabled. This is used for automatic autowiring options (the option must be marked as autowired) by looking up in the registry to find if there is a single instance of matching type, which then gets configured on the component. This can be used for automatic configuring JDBC data sources, JMS connection factories, AWS Clients, etc.

true

boolean

The String Template endpoint is configured using URI syntax:

string-template:resourceUri

with the following path and query parameters:

Path Parameters (1 parameters):

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

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 (6 parameters):

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
contentCache (producer)	Sets whether to use resource content cache or not	false	boolean
delimiterStart (producer)	The variable start delimiter	<	char
delimiterStop (producer)	The variable end delimiter	>	char
lazyStartProducer (producer)	Whether the producer should be started lazy (on the first message). By starting lazy you can use this to allow CamelContext and routes to startup in situations where a producer may otherwise fail during starting and cause the route to fail being started. By deferring this startup to be lazy then the startup failure can be handled during routing messages via Camel’s routing error handlers. Beware that when the first message is processed then creating and starting the producer may take a little time and prolong the total processing time of the processing.	false	boolean

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

contentCache (producer)

Sets whether to use resource content cache or not

false

boolean

delimiterStart (producer)

The variable start delimiter

<

char

delimiterStop (producer)

The variable end delimiter

>

char

lazyStartProducer (producer)

Whether the producer should be started lazy (on the first message). By starting lazy you can use this to allow CamelContext and routes to startup in situations where a producer may otherwise fail during starting and cause the route to fail being started. By deferring this startup to be lazy then the startup failure can be handled during routing messages via Camel’s routing error handlers. Beware that when the first message is processed then creating and starting the producer may take a little time and prolong the total processing time of the processing.

false

boolean

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 loads the resource only once and hot-reloading is not possible. This scenario can be used in production when the resource never changes.

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.

Header	Type	Description
CamelStringTemplateResourceUri	String	A URI for the template resource to use instead of the endpoint configured.
CamelStringTemplateTemplate	String	The template to use instead of the endpoint configured.

Header

Type

Description

CamelStringTemplateResourceUri

String

A URI for the template resource to use instead of the endpoint configured.

CamelStringTemplateTemplate

String

The template to use instead of the endpoint configured.

StringTemplate Attributes

You can define the custom context map by setting the message header "CamelStringTemplateVariableMap" just like the below code.

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:

Dear <headers.lastName>, <headers.firstName>

Thanks for the order of <headers.item>.

Regards Camel Riders Bookstore
<body>

And the java code is as follows:

Spring Boot Auto-Configuration

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

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

Name	Description	Default	Type
camel.component.string-template.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.string-template.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.string-template.autowired-enabled	Whether autowiring is enabled. This is used for automatic autowiring options (the option must be marked as autowired) by looking up in the registry to find if there is a single instance of matching type, which then gets configured on the component. This can be used for automatic configuring JDBC data sources, JMS connection factories, AWS Clients, etc.	true	Boolean
camel.component.string-template.enabled	Whether to enable auto configuration of the string-template component. This is enabled by default.		Boolean
camel.component.string-template.lazy-start-producer	Whether the producer should be started lazy (on the first message). By starting lazy you can use this to allow CamelContext and routes to startup in situations where a producer may otherwise fail during starting and cause the route to fail being started. By deferring this startup to be lazy then the startup failure can be handled during routing messages via Camel’s routing error handlers. Beware that when the first message is processed then creating and starting the producer may take a little time and prolong the total processing time of the processing.	false	Boolean

Name

Description

Default

Type

camel.component.string-template.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.string-template.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.string-template.autowired-enabled

Whether autowiring is enabled. This is used for automatic autowiring options (the option must be marked as autowired) by looking up in the registry to find if there is a single instance of matching type, which then gets configured on the component. This can be used for automatic configuring JDBC data sources, JMS connection factories, AWS Clients, etc.

true

Boolean

camel.component.string-template.enabled

Whether to enable auto configuration of the string-template component. This is enabled by default.

Boolean

camel.component.string-template.lazy-start-producer

Whether the producer should be started lazy (on the first message). By starting lazy you can use this to allow CamelContext and routes to startup in situations where a producer may otherwise fail during starting and cause the route to fail being started. By deferring this startup to be lazy then the startup failure can be handled during routing messages via Camel’s routing error handlers. Beware that when the first message is processed then creating and starting the producer may take a little time and prolong the total processing time of the processing.

false

Boolean