Dataweave Flashcards
(33 cards)
What is dataweave ?
Dataweave is a mulesoft expression language for accessing and transforming data that travels through a mule application.
Define and call a variable ?
%dw 2.0
var myJson = {"Hello" : "World"}
var cr=10
output application/json
---
{
myObjectVar : myJson,
price: cr*3
}
Output:
{
myObjectVar: {"Hello" : "World"},
price: 30
}
Use a dataweave function in a dataweave variable ?
%dw 2.0
var myJson = {
a: avg([1, 1000]),
b: avg([1, 2, 3])
}
output application/json
---
myJson
Output:
{
“a”: 500.5,
“b”: 2.0
}
Read, Transform and select content from an input
%dw 2.0
var myRead = read("red", "application/xml")
output application/json
---
{
mySelection : myRead.car
}
Output:
{
"mySelection": {
"color": "red"
}
}
What are the sections/parts in Dataweave script?
Header and Body
Concatenate Two Strings into a Single String
%dw 2.0
output application/json
—
{ myString: (“hello” ++ “World”) }
Output:
{
“myString”: “helloWorld”
}
What does the header contains?
Dataweave declaration : %dw 2.0 .. . . . . .
What is this declaration called ?
output application/json
Output directive
Read File Contents with a DataWeave Function
1. Create a file src/main/resources/myjson.json
{
"hello": "world"
}
2. Dataweave script
%dw 2.0
output application/json
---
readUrl("classpath://myJson.json", "application/json")
- Output:
{
“hello”: “world”
}
Extract only values from key value pairs in json
Use the pluck function
%dw 2.0
output application/json
---
{
"0": "a",
"1": "b",
"2": "c"
} pluck ((value) -> value)
Output: [ "a", "b", "c" ]
What does $$ indicate in map operator
Index of the array
What does $ indicate in map operator
The value/data at an index in the array
Filter an array with condition value >2
Input:
[9,2,3,4,5]
[9,2,3,4,5] filter (value,index) -> (value > 2)
[9,2,3,4,5] filter ($ >2)
Output:
[9,3,4,5]
Filter an array with condition index > 2
Input:
[9,2,3,4,5]
[9,2,3,4,5] filter (value,index -> (index > 2)
[9,2,3,4,5] filter ($$ >2)
Output:
[4,5]
Filter an array with condition index > 1 and value <5
Input:
[9,2,3,4,5]
[9,2,3,4,5] filter (($$ > 1) and ($ < 5))
Output:
[3,4]
What are these called ?
$$ and $
Anonymous parameters.
These are used in place of named parameters in anonymous function
How do you define date and time ?
Enclosed in pipes.
myDate: |2018-12-07|,
myTime: |11:55:56|,
myDateTime: |2018-10-01T23:57:59-03:00|,
Object with condition field ?
myObjectWithConditionalField: { a : { b : 1, ( c : 2 ) if true, (d : 4) if false } },
Define string as binary
myBinary: “abcd1234123” as Binary
What is pluck function and how to use it ?
Pluck function iterates over a json object and can be used to output values into an array.
%dw 2.0
output application/json
---
{
"0": "a",
"1": "b",
"2": "c"
} pluck ((value) -> value)
Output: [ "a", "b", "c" ]
Conditional check on a payload
ContainsRequestedItem: myInput.root.order.items contains “3”
Get current time ?
currTime: now()
Define and call a function ?
fun toUser(obj) = {
firstName: obj.field1,
lastName: obj.field2
}
What is the default output directive ?
application/java
