Predicate Filter Action

Provided by: "Apache Software Foundation"

Support Level for this Kamelet is: "Stable"

Filter based on a JsonPath Expression. Since this is a filter, the expression will be a negation, this means that if the foo field of the example is equals to John, the message will go ahead, otherwise it will be filtered out.

Configuration Options

The following table summarizes the configuration options available for the predicate-filter-action Kamelet:

Property	Name	Description	Type	Default	Example
expression	Expression	Required The JsonPath Expression to evaluate, without the external parenthesis. Since this is a filter, the expression will be a negation, this means that if the foo field of the example is equals to John, the message will go ahead, otherwise it will be filtered out.	string		@.foo =~ /.*John/

Property

Name

Description

Type

Default

Example

expression

Expression

Required The JsonPath Expression to evaluate, without the external parenthesis. Since this is a filter, the expression will be a negation, this means that if the foo field of the example is equals to John, the message will go ahead, otherwise it will be filtered out.

string

@.foo =~ /.*John/

Dependencies

At runtime, the predicate-filter-action Kamelet relies upon the presence of the following dependencies:

camel:core
camel:kamelet
camel:jsonpath

Camel JBang usage

Prerequisites

You’ve installed JBang.
You have executed the following command:

jbang app install camel@apache/camel

Supposing you have a file named route.yaml with this content:

- route:
    from:
      uri: "kamelet:timer-source"
      parameters:
        period: 10000
        message: 'test'
      steps:
        - to:
            uri: "kamelet:log-sink"

You can now run it directly through the following command

camel run route.yaml

Camel K Environment Usage

This section describes how you can use the predicate-filter-action.

Knative action

You can use the predicate-filter-action Kamelet as an intermediate step in a Knative binding.

predicate-filter-action-binding.yaml

apiVersion: camel.apache.org/v1
kind: KameletBinding
metadata:
  name: predicate-filter-action-binding
spec:
  source:
    ref:
      kind: Kamelet
      apiVersion: camel.apache.org/v1
      name: kafka-source
      properties:
        bootstrapServers: localhost:9092
        topic: mytopic
        user: kafka
        password: kafka123!
  steps:
    - ref:
        kind: Kamelet
        apiVersion: camel.apache.org/v1
        name: predicate-filter-action
      properties:
        expression: "@.foo =~ /.*John/"
  sink:
    ref:
      kind: Channel
      apiVersion: messaging.knative.dev/v1
      name: mychannel

Prerequisite

You have Camel K installed on the cluster.

Procedure for using the cluster CLI

Save the predicate-filter-action-binding.yaml file to your local drive, and then edit it as needed for your configuration.

Run the action by using the following command:

kubectl apply -f predicate-filter-action-binding.yaml

Procedure for using the Kamel CLI

Configure and run the action by using the following command:

kamel bind channel:mychannel -p "step-0.expression=@.foo =~ /.*John/" predicate-filter-action

This command creates the KameletBinding in the current namespace on the cluster.

Kafka action

You can use the predicate-filter-action Kamelet as an intermediate step in a Kafka binding.