Generating random numbers in mule dataweave

Question

I have to concatenate randomly generated number with the field from request in dataweave.

NUMBR: "AA" ++ $.Load.Reference.*Reference ++ RandomNumber

How to achieve this in Mule Dataweave

Answer 1

Not sure what you can do in Datawevae to do this, but you can you set a Random number in a flowVariable and invoke it from your Dataweave script like so:

<set-variable variableName="random"
    value="#[new java.util.Random().nextInt(100)]" doc:name="Variable" />

<dw:transform-message doc:name="Transform Message">
    <dw:input-variable doc:sample="unknown.dwl" variableName="random" />
    <dw:set-payload>
    <![CDATA[%dw 1.0
        %output application/dw
        ---
        {
            "data": ("22" as :number + flowVars.random)
        } ]]>
    </dw:set-payload>
</dw:transform-message>

Answer 2

You can also use Expression Component to assign it to Payload or variables and then concatenate

<flow name="random-numbersFlow">
    <http:listener config-ref="HTTP_Listener_Configuration" path="/random" allowedMethods="GET" doc:name="HTTP"/>
    <expression-component doc:name="Expression"><![CDATA[payload = new java.util.Random().nextInt(100)]]></expression-component>
    <dw:transform-message doc:name="Transform Message">
        <dw:set-payload><![CDATA[%dw 1.0
%output application/java
---
{
    data: payload
}]]></dw:set-payload>
    </dw:transform-message>
    <logger message="#[payload]" level="INFO" doc:name="Logger"/>
</flow>

Answer 3

You can't do this in pure DataWeave but you could use two methods to generate the number elsewhere in the application:

1. You could call a global MEL function from DataWeave: https://docs.mulesoft.com/mule-user-guide/v/3.7/dataweave-reference-documentation#global-mel-functions
2. You could call a flow that returns the value: https://docs.mulesoft.com/mule-user-guide/v/3.7/dataweave-reference-documentation#expressions-that-call-external-flows

Answer 4

Just set a random value generated by Java into a Flow Variable

<set-variable variableName="Random_Variable" value="#[java.util.Random().nextInt(10)]" doc:name="Random Variable"/>

Then Use that Flow Variable in your Dataweave Transform.

<dw:transform-message doc:name="Transform Message" metadata:id="8098b24c-30c1-4e9e-a3ce-9e8aaaec7bd1">
            <dw:input-variable mimeType="application/java" variableName="Random_Variable"/>
            <dw:set-payload><![CDATA[%dw 2.0
%output application/json
---
{
    NUMBR: "AA" ++ $.Load.Reference.*Reference ++ flowVars.Random_Variable
}]]></dw:set-payload>
</dw:transform-message>

Answer 5

In Mule 4 Dataweave 2 function radom()

Returns a pseudo-random number greater than or equal to 0.0 and less than 1.0

MULE 4 DOC: https://docs.mulesoft.com/mule-runtime/4.3/dw-core-functions-random

Example: %dw 2.0 output application/json

{ price: random() * 1000 }