Deep into Dataweave - Mule 4

1) Use vars as an ArrayList:

  Define the variable as an Array List using the below blank array (Use Set Variable activity):

      

   %dw 2.0

   output application/java

   ---

   []

 Add values to the existing variable Array List (Use another Set Variable activity):

    %dw 2.0

   output application/java

   ---

   vars.varList + payload

Lookup values from the variable ArrayList using the index:

    

      vars.varList[2]

Full flow mule xml:

<flow name="varsAsArrayList" doc:id="ad2a593a-e7cb-4cd6-a46a-3e87d30f95f8" >

             <set-payload value='#[%dw 2.0

output application/java

---

["First","Second","Third"]]' doc:name="Set Payload" doc:id="3ec00784-0453-44ce-baa9-71dc20ebbe1d" />

             <set-variable value="#[%dw 2.0

output application/java

---

[]]" doc:name="varList" doc:id="497a414b-b53c-4523-8b9a-9c4d5eeeda80" variableName="varList" />

             <foreach doc:name="For Each" doc:id="a8ea8c36-8055-4a98-bd98-db62d7f4697d" collection="#[payload]" >

                   <set-variable value="#[%dw 2.0

output application/java

---

vars.varList + payload]" doc:name="varList" doc:id="83ce95be-d6eb-4472-9edf-41f5f0aa510f" variableName="varList"/>

             </foreach>

             <logger level="INFO" doc:name="Logger" doc:id="bf81f0ac-e630-48a0-b00c-adf3cdb8bb9d" message="OP - #[vars.varList[2]]" />

</flow>

2) Use vars as a Map:

  Define the variable as a Map using the below expression (Use Set Variable activity):

   %dw 2.0

   output application/java

   ---

   {}

 Add values to the existing variable Map (Use another Set Variable activity):

  

   %dw 2.0

   import mergeWith from dw::core::Objects

   output application/java

   ---

   vars.varMap mergeWith { ('key'): payload }

  OR

   %dw 2.0

   output application/java

   ---

   vars.varMap ++ { ('key'): payload }

Lookup values from the variable Map using the key:

     syntax :  #[vars.varMap['key']]
     e.g:        #[vars.varMap['2']]      (2 is the key here)

Full flow mule xml:

<flow name="varsAsMap">

             <set-payload value='#[%dw 2.0

output application/java

---

["First","Second","Third"]]' doc:name="Set Payload" doc:id="ff22bb3b-bb0c-4336-9081-7db5aac860e1" />

             <set-variable value="#[%dw 2.0

output application/java

---

{}]" doc:name="varMap" doc:id="db60044d-f6e4-4efa-b10d-e3992592e2d3" variableName="varMap"/>

             <foreach doc:name="For Each" doc:id="73a42901-31bd-42ef-b338-44fa815e5cd1" collection="#[payload]">

                   <set-variable value="#[%dw 2.0

import mergeWith from dw::core::Objects

output application/java

---

vars.varMap mergeWith { (vars.counter): payload }]" doc:name="varMap" doc:id="24338e8d-1f3b-4caa-a6ba-5b98bb4c7bac" variableName="varMap" />

             </foreach>

             <logger level="INFO" doc:name="Logger" doc:id="99688a40-b3e3-4a10-a6dd-d773f79d28bb" message="OP - #[vars.varMap['2']]"/>

</flow>

3) dw cheat codes:

    a) Replace all special chars in a string:

         "Hello how are you!##"  replace /[^A-Za-z0-9]/ with "_"

4) Multiple Namespaces using DataWeave:

Expected Output -

 

<?xml version='1.0' encoding='UTF-8'?>
<pp:Root xmlns:pp="http://www.abc.org" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.abc.org/data/Sample1.0.0.xsd">
  <pp:Header>
    <pp:Element>Hello NameSpace</pp:Element>
  </pp:Header>
</pp:Root>

output application/xml

ns pp http://www.abc.org

var xmlnsxsi = "http://www.w3.org/2001/XMLSchema-instance"

var xsiSchemaLocation = "http://www.abc.org/data/Sample1.0.0.xsd"

---

{

       pp#Root @("xmlns:xsi": xmlnsxsi, "xsi:schemaLocation": xsiSchemaLocation): {

             pp#Header: {

                    pp#Element: "Hello NameSpace"

             }

       }

}