Choice flow in Mule

  Choice flow in Mule

The Choice router dynamically routes messages through a flow according to a set of DataWeave expressions that evaluate message content. Each expression is associated with a different routing option. The effect is to add conditional processing to a flow, similar to an if/then/else code block in most programming languages.


Choice Router XML Reference :

A Choice flow control component contains these elements:

A single root element <choice>

A <when> child element for each routing option, each with an expression to match

Optionally, an <otherwise> child element of Choice that handles all cases where none of the expressions on the <when> elements evaluate to true

Components that are conditionally executed under each of the choices are defined as child elements of the when and otherwise elements

Here we are using choice flow control in mule 3 in Anypoint studio 6.2

choice flow control routes the payload according to given condition in choice flow control, if condition is not met then it routes to default section.

Here we are routing payload according to 3 conditions :


1) if age is less than 18
2) if age is greater than 18
3) if age is equals to 18



Below is the basic flow of choice flow control





HTTP Listener Configuration :



path : /testchoice



We need to give condition in choice to route the payload shown below :





url : http://localhost:8085/api/testchoice

method : POST



 input:



output :



XML project code :

<?xml version="1.0" encoding="UTF-8"?>
<mule xmlns:json="http://www.mulesoft.org/schema/mule/json" xmlns:http="http://www.mulesoft.org/schema/mule/http" xmlns:tracking="http://www.mulesoft.org/schema/mule/ee/tracking" xmlns="http://www.mulesoft.org/schema/mule/core" xmlns:doc="http://www.mulesoft.org/schema/mule/documentation"
xmlns:spring="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-current.xsd
http://www.mulesoft.org/schema/mule/core http://www.mulesoft.org/schema/mule/core/current/mule.xsd
http://www.mulesoft.org/schema/mule/http http://www.mulesoft.org/schema/mule/http/current/mule-http.xsd
http://www.mulesoft.org/schema/mule/ee/tracking http://www.mulesoft.org/schema/mule/ee/tracking/current/mule-tracking-ee.xsd
http://www.mulesoft.org/schema/mule/json http://www.mulesoft.org/schema/mule/json/current/mule-json.xsd">
    <http:listener-config name="HTTP_Listener_Configuration" host="0.0.0.0" port="8085" basePath="/api" doc:name="HTTP Listener Configuration"/>
    <flow name="testchoiceFlow">
        <http:listener config-ref="HTTP_Listener_Configuration" path="/testchoice" doc:name="HTTP"/>
        <byte-array-to-string-transformer doc:name="Byte Array to String"/>
        <json:json-to-object-transformer returnClass="java.util.Map" doc:name="JSON to Object"/>
        <choice doc:name="Choice">
            <when expression="#[payload.age &lt; 18]">
                <set-payload doc:name="Age is &lt; 18" value="Age is less than 18 years"/>
            </when>
            <when expression="#[payload.age &gt; 18]">
                <set-payload doc:name="Age is &gt; 18" value="Age is greater than 18 years"/>
            </when>
            <otherwise>
                <set-payload doc:name="Age == 18" value="Age is equal to 18 years"/>
            </otherwise>
        </choice>
    </flow>
</mule>