Chapter 42. Predicate Filter Action
Filter based on a JsonPath Expression
42.1. Configuration Options
The following table summarizes the configuration options available for the predicate-filter-action
Kamelet:
Property | Name | Description | Type | Default | Example |
---|---|---|---|---|---|
expression * | Expression | 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 |
|
Fields marked with an asterisk (*) are mandatory.
42.2. Dependencies
At runtime, the predicate-filter-action
Kamelet relies upon the presence of the following dependencies:
- camel:core
- camel:kamelet
- camel:jsonpath
42.3. Usage
This section describes how you can use the predicate-filter-action
.
42.3.1. 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/v1alpha1 kind: KameletBinding metadata: name: predicate-filter-action-binding spec: source: ref: kind: Kamelet apiVersion: camel.apache.org/v1alpha1 name: timer-source properties: message: "Hello" steps: - ref: kind: Kamelet apiVersion: camel.apache.org/v1alpha1 name: predicate-filter-action properties: expression: "@.foo =~ /.*John/" sink: ref: kind: Channel apiVersion: messaging.knative.dev/v1 name: mychannel
42.3.1.1. Prerequisite
Make sure you have "Red Hat Integration - Camel K" installed into the OpenShift cluster you’re connected to.
42.3.1.2. 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:
oc apply -f predicate-filter-action-binding.yaml
42.3.1.3. Procedure for using the Kamel CLI
Configure and run the action by using the following command:
kamel bind timer-source?message=Hello --step predicate-filter-action -p "step-0.expression=@.foo =~ /.*John/" channel:mychannel
This command creates the KameletBinding in the current namespace on the cluster.
42.3.2. Kafka Action
You can use the predicate-filter-action
Kamelet as an intermediate step in a Kafka binding.
predicate-filter-action-binding.yaml
apiVersion: camel.apache.org/v1alpha1 kind: KameletBinding metadata: name: predicate-filter-action-binding spec: source: ref: kind: Kamelet apiVersion: camel.apache.org/v1alpha1 name: timer-source properties: message: "Hello" steps: - ref: kind: Kamelet apiVersion: camel.apache.org/v1alpha1 name: predicate-filter-action properties: expression: "@.foo =~ /.*John/" sink: ref: kind: KafkaTopic apiVersion: kafka.strimzi.io/v1beta1 name: my-topic
42.3.2.1. Prerequisites
Ensure that you’ve installed the AMQ Streams operator in your OpenShift cluster and created a topic named my-topic
in the current namespace. Make also sure you have "Red Hat Integration - Camel K" installed into the OpenShift cluster you’re connected to.
42.3.2.2. 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:
oc apply -f predicate-filter-action-binding.yaml
42.3.2.3. Procedure for using the Kamel CLI
Configure and run the action by using the following command:
kamel bind timer-source?message=Hello --step predicate-filter-action -p "step-0.expression=@.foo =~ /.*John/" kafka.strimzi.io/v1beta1:KafkaTopic:my-topic
This command creates the KameletBinding in the current namespace on the cluster.