Chapter 235. MVEL Language
Available as of Camel version 2.0
Camel allows Mvel to be used as an Expression or Predicate the DSL or Xml Configuration.
You could use Mvel to create an Predicate in a Message Filter or as an Expression for a Recipient List
You can use Mvel dot notation to invoke operations. If you for instance have a body that contains a POJO that has a getFamiliyName method then you can construct the syntax as follows:
"request.body.familyName" // or "getRequest().getBody().getFamilyName()"
235.1. Mvel Options
The MVEL language supports 1 options, which are listed below.
| Name | Default | Java Type | Description |
|---|---|---|---|
| trim |
|
| Whether to trim the value to remove leading and trailing whitespaces and line breaks |
235.2. Spring Boot Auto-Configuration
The component supports 4 options, which are listed below.
| Name | Description | Default | Type |
|---|---|---|---|
| camel.component.mvel.enabled | Enable mvel component | true | Boolean |
| camel.component.mvel.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 |
| camel.language.mvel.enabled | Enable mvel language | true | Boolean |
| camel.language.mvel.trim | Whether to trim the value to remove leading and trailing whitespaces and line breaks | true | Boolean |
235.3. Variables
| Variable | Type | Description |
|---|---|---|
| this | Exchange | the Exchange is the root object |
| exchange | Exchange | the Exchange object |
| exception | Throwable | the Exchange exception (if any) |
| exchangeId | String | the exchange id |
| fault | Message | the Fault message (if any) |
| request | Message | the exchange.in message |
| response | Message | the exchange.out message (if any) |
| properties | Map | the exchange properties |
| property(name) | Object | the property by the given name |
| property(name, type) | Type | the property by the given name as the given type |
235.4. Samples
For example you could use Mvel inside a Message Filter in XML
<route>
<from uri="seda:foo"/>
<filter>
<mvel>request.headers.foo == 'bar'</mvel>
<to uri="seda:bar"/>
</filter>
</route>And the sample using Java DSL:
from("seda:foo").filter().mvel("request.headers.foo == 'bar'").to("seda:bar");235.5. Loading script from external resource
Available as of Camel 2.11
You can externalize the script and have Camel load it from a resource such as "classpath:", "file:", or "http:".
This is done using the following syntax: "resource:scheme:location", eg to refer to a file on the classpath you can do:
.setHeader("myHeader").mvel("resource:classpath:script.mvel")235.6. Dependencies
To use Mvel in your camel routes you need to add the a dependency on camel-mvel which implements the Mvel language.
If you use maven you could just add the following to your pom.xml, substituting the version number for the latest & greatest release (see the download page for the latest versions).
<dependency> <groupId>org.apache.camel</groupId> <artifactId>camel-mvel</artifactId> <version>x.x.x</version> </dependency>
