%dw 2.0
output application/json
---
{ "mathOperators" : [
{ "2 + 2" : (2 + 2) },
{ "2 - 2" : (2 - 2) },
{ "2 * 2" : (2 * 2) },
{ "2 / 2" : (2 / 2) },
{ "[1,2,3] - 1 + 4" : [1,2,3] - 1 + 4},
{ "{a:1, b:2, c:3} - 'a' " : {a:1, b:2, c:3} - "a"},
{ "|2021-03-02T10:39:59| - |P1D| + |PT3H|" : |2021-03-02T10:39:59| - |P1D| + |PT3H|}
]
}
DataWeave Operators
DataWeave version 2 supports several operators, including mathematical operators, equality operators, and operators such as prepend, append and update. Before you begin, note that DataWeave version 2 is for Mule 4 apps. For Mule 3 apps, refer to DataWeave Operators in the Mule 3.9 documentation. For other Mule versions, you can use the version selector for the Mule Runtime table of contents.
Mathematical Operators
DataWeave version 2 supports the most common mathematical operators:
Operator | Description |
---|---|
|
For addition. |
|
For subtraction. |
|
For multiplication. |
|
For division. |
In addition to operating with numbers, the (-)
and (+)
operators can also operate with complex data structures like arrays, objects, and dates.
The following example uses mathematical operators with different data types:
{
"mathOperators": [
{ "2 + 2": 4 },
{ "2 - 2": 0 },
{ "2 * 2": 4 },
{ "2 / 2": 1 },
{ "[1,2,3] - 1 + 4": [2,3,4] },
{ "{a:1, b:2, c:3} - 'a' ": {"b": 2, "c": 3} },
{ "|2021-03-02T10:39:59| - |P1D| + |PT3H|": "2021-03-01T13:39:59" }]
}
Equality and Relational Operators
DataWeave version 2 supports the following equality and relational operators:
Operator | Description |
---|---|
|
For less than. |
|
For greater than. |
|
For less than or equal to. |
|
For greater than or equal to. |
|
For equal to. |
|
Equality operator that tries to coerce one value to the type of the other when the types are different. |
Note that you can negate these operators by using the logical operator, not
.
The following example uses relational operators:
%dw 2.0
output application/json
---
{ "relational" : [
{ "1 < 1" : (1 < 1) },
{ "1 > 2" : (1 > 2) },
{ "1 <= 1" : (1 <= 1) },
{ "1 >= 1" : (1 >= 1) }
]
}
{ "relational": [
{ "(1 < 1)": false },
{ "(1 > 2)": false },
{ "(1 <= 1)": true },
{ "(1 >= 1)": true }
]
}
Note that if the operands of the relational operator belong to different types,
DataWeave coerces the right-side operand to the type of the left-side operand.
For example, in the expression "123" > 12
DataWeave coerces 12
(a Number type)
to "12"
(a String type) and compares each String value lexicographically.
In the expression 123 > "12"
, DataWeave coerces the String value "12"
to the Number value 12
and compares the numbers.
These examples use equality operators:
%dw 2.0
output application/dw
---
{ "equality" :
[
(1 == 1),
(1 == 2),
("true" == true),
("true" ~= true),
(['true'] ~= [true]),
('1' ~= 1)
]
}
{
equality: [ true, false, false, true, true, true ]
}
Logical Operators
DataWeave version 2 supports the following logical operators:
Operator | Description |
---|---|
|
Negates the result of the input. See also, |
|
Negates the result of the input. See also, |
|
Returns |
|
Returns |
Though the semantics of not and ! are the same, their precedence
differs. not true or true is executed as not (true or true) ,
so it returns false , whereas !true or true returns true because
the ! only applies to the first true . !(true or true) returns
false .
|
The following examples use logical operators:
%dw 2.0
var myArray = [1,2,3,4,5]
var myMap = myArray map not (($ mod 2) == 0)
output application/json
---
{
"not" : [
"notTrue" : not true,
"notFalse" : not false,
"myMapWithNot" : myMap
],
"and" : [
"andTrueFalse" : true and false,
"andIsTrue" : (1 + 1 == 2) and (2 + 2 == 4),
"andIsFalse" : (1 + 1 == 2) and (2 + 2 == 2)
],
"or" : [
"orTrueFalse" : true or false,
"orIsTrue" : (1 + 1 == 2) or (2 + 2 == 2),
"orIsFalse" : (1 + 1 == 1) or (2 + 2 == 2)
],
"!-vs-not" : [
"example-!" : (! true or true),
"example-not" : (not true or true)
]
}
Note that myMap
iterates through the items in a list (myArray
) and
determines whether the modulo (mod
) expression does not evaluate to 0
when
applied to each given item.
{
"not": [
{ "notTrue": false },
{ "notFalse": true },
{ "myMapWithNot": [ true, false, true, false, true ] }
],
"and": [
{ "andTrueFalse": false },
{ "andIsTrue": true },
{ "andIsFalse": false }
],
"or": [
{ "orTrueFalse": true },
{ "orIsTrue": true },
{ "orIsFalse": false }
],
"!-vs-not": [
{ "example-!": true },
{ "example-not": false }
]
}
Note that not
works in expressions such as not (true)
, but not(true)
(without the space) does not work.
You can use logical operators together. The following example uses:
-
or not
as defined in theorNot
expression. -
and not
inandNot
. -
not
andand not
innotWithAndNot
.
%dw 2.0
var orNot = if (1 + 1 == 4 or not 1 == 2) {"answer": "orNot - Condition met"}
else {"answer": "nope"}
var andNot = if (1 + 1 == 2 and not 1 == 2) {"answer": "andNot - Condition met"}
else {"answer": "nope"}
var notWithAndNot = if (not (1 + 1 == 2 and not 1 == 1)) {"answer": "notWithAndNot - Condition met"}
else {"answer": "nope"}
output application/json
---
{ "answers" :
[
orNot,
andNot,
notWithAndNot
]
}
{
"answers": [
{ "answer": "orNot - Condition met" },
{ "answer": "andNot - Condition met" },
{ "answer": "notWithAndNot - Condition met" }
]
}
DataWeave executes the code inside each if
block because all conditional expressions in the example evaluate to true
.
Prepend, Append, and Remove Operators for Arrays
DataWeave version 2 supports operators for appending and prepending items within an array:
Operator | Description |
---|---|
|
Prepends data on the left-hand side of the operator to items in the
array on the right-hand side. For example, |
|
Appends data on the right-hand side of the operator to items in the
array on the left-hand side. For example, |
|
Appends data on the right-hand side of the operator to items in the
array on the left-hand side. For example, |
|
Removes a specified element of any supported type from an array. |
The following examples show uses of prepend, append, and remove operators on arrays:
%dw 2.0
output application/json
---
{
"prepend-append" : [
// Array on right side when prepending.
{ "prepend" : 1 >> [2] },
{ "prepend-number" : 1 >> [1] },
{ "prepend-string" : "a" >> [1] },
{ "prepend-object" : { "a" : "b"} >> [1] },
{ "prepend-array" : [1] >> [2, 3] },
{ "prepend-binary" : (1 as Binary) >> [1] },
{ "prepend-date-time" : |23:57:59Z| >> [ |2017-10-01| ] },
// Array is on left side when appending.
{ "append-number" : [1] << 2 },
{ "append-string" : [1] << "a" },
{ "append-object" : [1] << { "a" : "b"} },
{ "append-array" : [1,2] << [1, 2, 3] },
{ "append-binary" : [1] << (1 as Binary) },
{ "append-date-time" : [ |2017-10-01| ] << |23:57:59Z| },
{ "append-object-to-array" : [1,2] << {"a" : "b"} },
{ "append-array-to-array1" : ["a","b"] << ["c","d"] },
{ "append-array-to-array2" : [["a","b"],["c","d"]] << ["e","f"] },
// + always appends within the array
{ "append-with-+" : [1] + 2 },
{ "append-with-+" : [2] + 1 },
{ "removeNumberFromArray" : ( [1,2,3] - 2 ) },
{ "removeObjectFromArray" : ( [ {a : "b"}, {c : "d"} , { e : "f"} ] - { c : "d"} ) }
]
}
{
"prepend-append": [
{ "prepend": [ 1, 2 ] },
{ "prepend-number": [ 1, 1 ] },
{ "prepend-string": [ "a", 1 ] },
{ "prepend-array": [ [ 1 ], 2, 3 ] },
{ "prepend-object": [ { "a": "b" }, 1 ] },
{ "prepend-binary": [ "\u0001", 1 ] },
{ "prepend-date-time": [ "23:57:59Z", "2017-10-01" ] },
{ "append-number": [ 1, 2 ] },
{ "append-string": [ 1, "a" ] },
{ "append-object": [ 1, { "a": "b" } ] },
{ "append-array": [ 1, 2, [ 1, 2, 3 ] ] },
{ "append-binary": [ 1, "\u0001" ] },
{ "append-date-time": [ "2017-10-01", "23:57:59Z" ] },
{ "append-object-to-array": [ 1, 2, { "a": "b" } ] },
{ "append-array-to-array1": [ "a", "b", ["c","d"] ] },
{ "append-array-to-array2": [ ["a","b"], ["c","d"], ["e","f"] ] },
{ "append-with-+": [ 1, 2] },
{ "append-with-+": [ 2, 1] },
{ "removeNumberFromArray": [ 1, 3 ] },
{ "removeObjectFromArray": [ { "a": "b" }, { "e": "f" } ] }
]
}
Scope and Flow Control Operators
DataWeave version 2 supports operators that control the flow and scope of expressions:
Operator | Description |
---|---|
|
Creates a scope in which new variables, functions, annotations, or namespaces can be declared and used. The syntax is similar to a mapping in that it is composed of a header and body separated by |
|
Replaced by |
Operator | Description |
---|---|
|
An |
|
An |
Update Operator
DataWeave supports the update
operator, which enables you to update specified fields of a data structure with new values.
Introduced in DataWeave 2.3.0. Supported by Mule 4.3 and later.
Versions prior to Mule 4.3 require the following syntax to increase the age
value in myInput
by one without recreating the entire object:
%dw 2.0
var myInput = {
"name": "Ken",
"lastName":"Shokida",
"age": 30
}
output application/json
---
myInput mapObject ((value,key) ->
if(key as String == "age")
{(key): value as Number + 1}
else
{(key): value} )
In Mule 4.3, the update
operator simplifies the syntax:
%dw 2.0
var myInput = {
"name": "Ken",
"lastName":"Shokida",
"age": 30
}
output application/json
---
myInput update {
case age at .age -> age + 1
}
Both DataWeave scripts return the same result:
{
"name": "Ken",
"lastName": "Shokida",
"age": 31
}
With update
, casting or iterating through all the key-value pairs is not necessary.
The update
syntax is as follows:
<value_to_update> update {
case <variable_name> at <update_expression>[!]? [if(<conditional_expression>)]? -> <new value>
...
}
-
value_to_update
represents the original value to update. -
update_expression
is the selector expression that matches a value invalue_to_update
. -
variable_name
is the name of the variable to bind to the matchedupdate_expression
value. -
new_value
is the expression with the new value. -
[if(<conditional_expression>)]?
Ifconditional_expression
returnstrue
, the script updates the value. Use of a conditional expression is optional. -
[!]
marks the selector as an upsert. If the expression doesn’t find a match, the!
makes theupdate
operator create all the required elements and insert the new value. -
update_expression
supports multiplecase
expressions.
The update operator doesn’t mutate the existing value. Instead, the operator creates a new value with the updated expressions.
|
Selector Expressions
Use selector expressions with the update
operator to specify the fields to update.
Value Selector
This matching selector can check for matches to any value within an object.
The following example updates a field at the root level and a field in a nested level using the value selector:
%dw 2.0
var myInput = {
"name": "Ken",
"lastName":"Shokida",
"age": 30,
"address": {
"street": "Amenabar",
"zipCode": "AB1234"
}
}
output application/json
---
myInput update {
case age at .age -> age + 1
case s at .address.street -> "First Street"
}
{
"name": "Ken",
"lastName": "Shokida",
"age": 31,
"address": {
"street": "First Street",
"zipCode": "AB1234"
}
}
Index Selector
This matching selector enables you to match any array by its index.
The following example updates an element that is at the first location of the array:
{
"name": "Ken",
"lastName":"Shokida",
"age": 30,
"addresses": [{
"street": "Amenabar",
"zipCode": "AB1234"
}]
}
%dw 2.0
output application/json
---
payload update {
case s at .addresses[0] -> {
"street": "Second Street",
"zipCode": "ZZ123"
}
}
{
"name": "Ken",
"lastName": "Shokida",
"age": 30,
"addresses": [
{
"street": "Second Street",
"zipCode": "ZZ123"
}
]
}
Attribute Selector
This matching selector enables you to match any attribute value.
The following example updates an attribute value and changes it to upper case:
<user name="leandro"/>
%dw 2.0
output application/xml
---
payload update {
case name at .user.@name -> upper(name)
}
<?xml version='1.0' encoding='UTF-8'?>
<user name="LEANDRO"/>
Dynamic Selector
Any selector can incorporate an expression to make the selection dynamic.
The following example dynamically selects and updates the value of a field that is not hardcoded. Such a field can change at runtime. The example uses the variable theFieldName
to obtain the field with key name
, and it changes the value of that field to Shoki
.
{
"name": "Ken",
"lastName":"Shokida"
}
%dw 2.0
var theFieldName = "name"
output application/json
---
payload update {
case s at ."$(theFieldName)" -> "Shoki"
}
{
"name": "Shoki",
"lastName": "Shokida"
}
Conditional Update
The update
operator has syntax for writing a conditional update if you want to modify a field under a given condition.
The following example updates the category based on the name of the user:
[{"name": "Ken", "age": 30}, {"name": "Tomo", "age": 70}, {"name": "Kajika", "age": 10}]
%dw 2.0
output application/json
---
payload map ((user) ->
user update {
case name at .name if(name == "Ken") -> name ++ " (Leandro)"
case name at .name if(name == "Tomo") -> name ++ " (Christian)"
}
)
[
{
"name": "Ken (Leandro)",
"age": 30
},
{
"name": "Tomo (Christian)",
"age": 70
},
{
"name": "Kajika",
"age": 10
}
]
Upserting
The update
operator enables you to insert a field that is not present already by using the !
symbol at the end of the selector expression. When the field is not present, the operator binds a null
value to the variable.
The following example updates each object in the array myInput
. If the field name
is present in the object, the example applies the upper
function to the value of name
. If the field name
is not present in the object, the example appends the key-value pair "name": "JOHN"
to the object.
%dw 2.0
var myInput = [{"lastName": "Doe"}, {"lastName": "Parker", "name": "Peter" }]
output application/json
---
myInput map ((value) ->
value update {
case name at .name! -> if(name == null) "JOHN" else upper(name)
}
)
[
{
"lastName": "Doe",
"name": "JOHN"
},
{
"lastName": "Parker",
"name": "PETER"
}
]
Sugar Syntax
The update
operator accepts a default variable named $
in place of the longer <variable_name> at
syntax.
The following example binds the value of the expression .age
to the default variable name $
, which is used to express the new value. The longer equivalent is shown in comments.
{
"name": "Ken",
"lastName":"Shokida",
"age": 30,
"address": {
"street": "Amenabar",
"zipCode": "AB1234"
}
}
%dw 2.0
output application/json
---
payload update {
//equivalent expression:
//case age at .age -> age + 1
case .age -> $ + 1
case .address.street -> "First Street"
}
{
"name": "Ken",
"lastName": "Shokida",
"age": 31,
"address": {
"street": "First Street",
"zipCode": "AB1234"
}
}