= DataSonnet Language
:doctitle: DataSonnet
:shortname: datasonnet
:artifactid: camel-datasonnet
:description: To use DataSonnet scripts for message transformations.
:since: 3.7
:supportlevel: Stable
//Manually maintained attributes
:camel-spring-boot-name: datasonnet

*Since Camel {since}*

Camel supports https://datasonnet.com/[DataSonnet] transformations to allow an
xref:manual::expression.adoc[Expression] or xref:manual::predicate.adoc[Predicate] to be
used in the xref:manual::dsl.adoc[DSL].

For example, you could use DataSonnet to create a
Predicate in a xref:eips:filter-eip.adoc[Message
Filter] or as an Expression for a
xref:eips:recipientList-eip.adoc[Recipient List].

To use a DataSonnet expression use the following Java code:

[source,java]
---------------------------------------
datasonnet("someDSExpression")
---------------------------------------

== DataSonnet Options

// language options: START
include::partial$language-options.adoc[]
// language options: END

== Example

Here is a simple example using a DataSonnet expression as a predicate in a Message Filter:

[source,java]
------------------------------------------------------------------------------------------------
// lets route if a line item is over $100
from("queue:foo")
    .filter(datasonnet("ds.arrays.firstWith(body.lineItems, function(item) item > 100) != null"))
    .to("queue:bar")
------------------------------------------------------------------------------------------------

And the XML DSL:

[source,xml]
-----------------------------------------------------------------------------
<route>
    <from uri="queue:foo"/>
    <filter>
        <datasonnet>ds.arrays.firstWith(body.lineItems, function(item) item > 100) != null</datasonnet>
        <to uri="queue:bar"/>
    </filter>
</route>
-----------------------------------------------------------------------------

Here is an example of a simple DataSonnet expression as a transformation EIP. This example will transform an XML body with
`lineItems` into JSON while filtering out lines that are under 100.

[source,java]
------------------------------------------------------------------------------------------------
from("queue:foo")
    .transform(datasonnet("ds.filter(body.lineItems, function(item) item > 100)", String.class)
        .bodyMediaType("application/xml").outputMediaType("application/json")
    )
    .to("queue:bar")
------------------------------------------------------------------------------------------------

And the XML DSL:

[source,xml]
-----------------------------------------------------------------------------
<route>
    <from uri="queue:foo"/>
    <filter>
        <datasonnet bodyMediaType="application/xml" outputMediaType="application/json" resultTypeName="java.lang.String" >
            ds.filter(body.lineItems, function(item) item > 100)
        </datasonnet>
        <to uri="queue:bar"/>
    </filter>
</route>
-----------------------------------------------------------------------------

== Setting result type

The xref:datasonnet-language.adoc[DataSonnet] expression will return a `com.datasonnet.document.Document` by default. The
document preserves the content type metadata along with the contents of the result of the transformation. In predicates,
however, the Document will be automatically unwrapped and the boolean content will be returned. Similarly any times you
want the content in a specific result type like a String. To do this you have to instruct the
xref:datasonnet-language.adoc[DataSonnet] which result type to return.

In Java DSL:

[source,java]
----
datasonnet("body.foo", String.class)
----

In XML DSL you use the *resultType* attribute to provide a fully
qualified classname:

[source,xml]
----
<datasonnet resultType="java.lang.String">body.foo</datasonnet>
----

If the expression results in an array, or an object, you can instruct the expression to return you `List.class`
or `Map.class`, respectively. However, you must also set the output media type to `application/x-java-object`.

NOTE: The default `Document` object is useful in situations where there are intermediate transformation steps, and so
retaining the content metadata through a route execution is valuable.

== Specifying Media Types

Traditionally the input and output media types are specified through the
https://datasonnet.s3-us-west-2.amazonaws.com/docs-ci/primary/master/datasonnet/1.0-SNAPSHOT/headers.html[DataSonnet Header]
The xref:datasonnet-language.adoc[DataSonnet] expression provides convenience options for specifying the body and output
media types without the need for a Header, this is useful if the transformation is a one-liner, for example.

The DataSonnet expression will look for a body media type in the following order:

1. If the body is a `Document` it will use the metadata in the object
2. If the convenience bodyMediaType method was used, it will use its value
3. A "CamelDatasonnetBodyMediaType" exchange property
4. A "Content-Type" message header
5. The DataSonnet Header payload media type directive
6. `application/x-java-object`

And for output media type:

1. If the convenience outputMediaType method was used, it will use its value
2. A "CamelDatasonnetOutputMediaType" exchange property
3. A "CamelDatasonnetOutputMediaType" message header
4. The DataSonnet Header output media type directive
5. `application/x-java-object`

== Functions

Camel adds the following DataSonnet functions that can be used to access the
exchange:

[width="100%",cols="10%,10%,10%,70%",options="header",]
|===
|Function |Argument |Type |Description

|cml.properties |key for property |String |To lookup a property using the
xref:ROOT:properties-component.adoc[Properties] component (property placeholders).

|cml.header |the header name |String |Will return the message header.

|cml.exchangeProperty |key for property |String |Will return the exchange property.
|===

Here's an example showing some of these functions in use:

[source,java]
------------------------------------------------------------------------------------------------
from("direct:in")
    .setBody(datasonnet("'hello, ' + cml.properties('toGreet')", String.class))
    .to("mock:camel");
------------------------------------------------------------------------------------------------

And the XML DSL:

[source,xml]
-----------------------------------------------------------------------------
<route>
    <from uri="direct:in"/>
    <setBody>
        <datasonnet resultTypeName="java.lang.String">'hello, ' + cml.properties('toGreet')</datasonnet>
    </setBody>
    <to uri="mock:camel"/>
</route>
-----------------------------------------------------------------------------

== Loading script from external resource

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:

[source,java]
-------------------------------------------------------------------
.setHeader("myHeader").datasonnet("resource:classpath:mydatasonnet.ds")
-------------------------------------------------------------------

== Dependencies

To use scripting languages in your camel routes you need to add a
dependency on *camel-datasonnet*.

If you use Maven you could just add the following to your `pom.xml`,
substituting the version number for the latest and greatest release (see
the download page for the latest versions).

[source,xml]
---------------------------------------
<dependency>
  <groupId>org.apache.camel</groupId>
  <artifactId>camel-datasonnet</artifactId>
  <version>x.x.x</version>
</dependency>
---------------------------------------


include::spring-boot:partial$starter.adoc[]
