Dataweave 1.0 in Mule | Variables | Functions | Data Types




Dataweave 1.0 in Mule

Defining variable in dataweave : 

%dw 1.0
%var rate=5
%output application/json
---
{
variable value : rate
currency: payload.price * rate
}

Defining function in dataweave : 

%dw 1.0
%output application/json
%function name(user){firstName: payload.name}
---
{
 user: name(payload)
}

Data types in mule : 

Simple values can be of the following types:

String : Double quoted ("Hello") or Single quoted ('Hello')

Boolean : Literals true or false

Number : Decimal and Integer values are supported (ex: 2.0)

Date : IS0-8601 enclosed by "|" (ex:|2003-10-01T23:57:59Z|)

Regex : Regex expression enclosed by "/" (ex:/(\d+)-(\d+)/)


Adding data to an existing input payload : 

input : 

{
"id" : 1
}

%dw 1.0
%output application/json

---
{
"id" : payload.id + 3
}


Flow Control Expressions :

1)When Otherwise

The keyword when conditionally evaluates a part of your DataWeave code, depending on if an expression evaluates to true or to false. You can make a single line conditional, or enclose a whole section in curly brackets. In case the when expression evaluates to false, its corresponding part of the code is ignored, and the code that corresponds to the otherwise expression is executed.

%dw 1.0
%output application/json

---
{
"id" : payload when payload.id > 2 otherwise null
}

2) Unless Otherwise

The keyword unless conditionally evaluates a part of your DataWeave code, depending on if an expression evaluates to true or to false. You can make a single line conditional, or enclose a whole section in curly brackets. In case the unless expression evaluates to true, its corresponding part of the code is ignored, and the code that corresponds to the otherwise expression is executed.

%dw 1.0
%output application/json

---
{
"id" : payload unless payload.id > 2 otherwise null
}

3) Default

Assigns a default value in case no value is found in the input field.

%dw 1.0
%output application/json

---
{
"id" : payload.id default 2
}

Matching Patterns in Mule 

1) Expression Pattern

Matches when running a certain expression over the evaluated value returns true.

Transform
%dw 1.0
%output application/json
---
{
  a: payload.string match {
    str when str == "Mariano" -> str ++ " de Achaval",
    str when str == "Emiliano" -> str ++ " Lesende"
  },
  b: payload.number match {
    n when n < 3 -> "lower",
    n when n > 3 -> "higher"
  }
}

Input: JSON
Input
{
  "string": "Emiliano",
  "number": 3.14
}
Output: JSON
Output
{
  "a": "Emiliano Lesende",
  "b": "higher"
}

2) Match Type
Matches when the evaluated value is of the specified type

Transform
%dw 1.0
%output application/json
---
{
  a: payload.a match {
    :object -> "OBJECT",
    :string -> "STRING",
    :number -> "NUMBER",
    :boolean -> "BOOLEAN",
    :array -> "ARRAY",
    :null -> "NULL"
  },
  b: payload.b match {
    y is :object -> { type: "OBJECT", y: y },
    y is :string -> { type: "STRING", y: y },
    y is :number -> { type: "NUMBER", y: y },
    y is :boolean -> { type: "BOOLEAN", y: y },
    y is :array -> { type: "ARRAY", y: y },
    y is :null -> { type: "NULL", y: y }
  }
}
Input: JSON
Input
{
  "a": "Emiliano",
  "b": 3.14
}
Output: JSON
Output
{
  "a": "STRING",
  "b": {
    "type": "NUMBER",
    "y": 3.14
  }
}

3) Match Regex
Matches when the evaluated value fits a given regular expression

Transform
%dw 1.0
%output application/json
---
{
  a: payload.phones map ($ match {
     /\+(\d+)\s\((\d+)\)\s(\d+\-\d+)/ -> { country: $[0], area: $[1], number: $[2] },
     /\((\d+)\)\s(\d+\-\d+)/ -> { area: $[1], number: $[2] }
   }),
 b: payload.phones map ($ match {
   phone: /\+(\d+)\s\((\d+)\)\s(\d+\-\d+)/ -> { country: phone[0], area: phone[1], number: phone[2] },
   phone: /\((\d+)\)\s(\d+\-\d+)/ -> { area: phone[1], number: phone[2] }
 })
}
Input: JSON
Input
{
  "phones": [
    "+1 (415) 229-2009",
    "(647) 456-7008"
  ]
}
Output: JSON
Output
{
  "a": [
    {
      "country": "+1 (415) 229-2009",
      "area": "1",
      "number": "415"
    },
    {
      "area": "647",
      "number": "456-7008"
    }
  ],
  "b": [
    {
      "country": "+1 (415) 229-2009",
      "area": "1",
      "number": "415"
    },
    {
      "area": "647",
      "number": "456-7008"
    }
  ]
}

System Values in Mule

1) Now
Returns the present moment in (:datetime) type.

Transform
%dw 1.0
%output application/json
---
{
  a: now,
  b: now.day,
  c: now.minutes
}

2) Random
Returns a random number of type (:number) between 0 and 1

Transform
%dw 1.0
%output application/json
---
{
  price: random * 1000
}


3) Log
(prefix :string,value :any)
Returns the specified value and also logs the value in the DataWeave representation with the specified prefix.

Transform
%dw 1.0
%output application/json
---
{
  result: log("Logging the array",[1,2,3,4])
}
Output
{
  "result": [1,2,3,4]
}
Logger output :

Logging the array [1,2,3,4]


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