JQ

Since Camel 3.18

Camel supports JQ to allow using Expression or Predicate on JSON messages.

JQ Options

The JQ language supports 3 options, which are listed below.

Name Default Java Type Description

source (common)

String

Source to use, instead of message body. You can prefix with variable:, header:, or property: to specify kind of source. Otherwise, the source is assumed to be a variable. Use empty or null to use default source, which is the message body.

resultType (common)

String

Sets the class of the result type (type from output).

trim (advanced)

true

Boolean

Whether to trim the value to remove leading and trailing whitespaces and line breaks.

Examples

For example, you can use JQ in a Predicate with the Content-Based Router EIP.

from("queue:books.new")
  .choice()
    .when().jq(".store.book.price < 10)")
      .to("jms:queue:book.cheap")
    .when().jq(".store.book.price < 30)")
      .to("jms:queue:book.average")
    .otherwise()
      .to("jms:queue:book.expensive");

Message body types

Camel JQ leverages camel-jackson for type conversion. To enable camel-jackson POJO type conversion, refer to the Camel Jackson documentation.

Using header as input

By default, JQ uses the message body as the input source. However, you can also use a header as input by specifying the headerName option.

For example, to count the number of books from a JSON document that was stored in a header named books you can do:

from("direct:start")
    .setHeader("numberOfBooks")
        .jq(".store.books | length", int.class, "books")
    .to("mock:result");

Camel supplied JQ Functions

JQ comes with about a hundred built-in functions, and you can see many examples from JQ documentation.

The camel-jq adds the following functions:

  • header: allow accessing the Message header in a JQ expression.

  • property: allow accessing the Exchange property in a JQ expression.

  • constant: allow using a constant value as-is in a JQ expression.

For example, to set the property foo with the value from the Message header `MyHeader':

from("direct:start")
    .transform()
        .jq(".foo = header(\"MyHeader\")")
    .to("mock:result");

Or from the exchange property:

from("direct:start")
    .transform()
        .jq(".foo = property(\"MyProperty\")")
    .to("mock:result");

And using a constant value

from("direct:start")
    .transform()
        .jq(".foo = constant(\"Hello World\")")
    .to("mock:result");

Transforming a JSon message

For basic JSon transformation where you have a fixed structure, you can represent with a combination of using Camel simple and JQ language as:

{
  "company": "${jq(.customer.name)}",
  "location": "${jq(.customer.address.country)}",
  "gold": ${jq(.customer.orders[] | length > 5)}
}

Here we use the simple language to define the structure and use JQ as inlined functions via the ${jq(exp)} syntax.

This makes it possible to use simple as a template language to define a basic structure and then JQ to grab the data from an incoming JSon message. The output of the transformation is also JSon, but with simple you could also make it XML or plain text based:

<customer gold="${jq(.customer.orders[] | length > 5)}">
    <company>${jq(.customer.name)}</company>
    <location>${jq(.customer.address.country)}</location>
</customer>

Dependencies

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).

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

Spring Boot Auto-Configuration

When using jq 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-jq-starter</artifactId>
  <version>x.x.x</version>
  <!-- use the same version as your Camel core version -->
</dependency>

The component supports 3 options, which are listed below.

Name Description Default Type

camel.language.jq.enabled

Whether to enable auto configuration of the jq language. This is enabled by default.

Boolean

camel.language.jq.source

Source to use, instead of message body. You can prefix with variable:, header:, or property: to specify kind of source. Otherwise, the source is assumed to be a variable. Use empty or null to use default source, which is the message body.

String

camel.language.jq.trim

Whether to trim the value to remove leading and trailing whitespaces and line breaks.

true

Boolean
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