This document was presented in Vancouver Canada MuleSoft Meetup held on 19th Nov 2020.

1. Vancouver Canada
19th Nov 2020
Reviewing a Complex DataWeave Transformation
Use-case

2. Presenters,Organizers and You
Vishal Aggarwal Yashwant Palkar Alexandra Martinez

3. Alexandra Martinez
Reviewing a Complex DataWeave
Transformation Use-case

4. 4
● Functions (fun)
○ Parameters using types
○ Calling functions with 2 parameters
● Variables (var)
● do statement to create scopes (local variables)
● Object manipulation using object destructor {( )}
● If/else
● Selectors:
○ Index (array[0])
○ Range (1 to 10)
● Setting default values
● Core functions/operators
○ isEmpty, reduce, map, groupBy, flatten
○ Remove (-), Sum (+), Concatenation (++), Prepend (>>)
Solution will make use of the following:

5. Requirement

6. 6
Input JSON structure to Output JSON structure
Requirement

7. 7
● Logic:
1. For each object from the
FlightOptions array, create one
output object inside the output array.
Requirement
7

8. 8
● Logic:
1. For each object from the
FlightOptions array, create one
output object inside the output array.
2. The AppliedTaxCode will contain the
value from the last Connection
object.
Requirement
8

9. 9
● Logic:
1. For each object from the
FlightOptions array, create one
output object inside the output array.
2. The AppliedTaxCode will contain the
value from the last Connection
object.
3. If the EndOfConnection field is true,
create a separate output object.
Requirement
9

10. 10
● Logic:
1. For each object from the
FlightOptions array, create one
output object inside the output array.
2. The AppliedTaxCode will contain the
value from the last Connection
object.
3. If the EndOfConnection field is true,
create a separate output object.
4. If there are EndOfConnection fields
that are true and this is not the last
object inside the Connections array,
create a new output object
containing all the false Connection
objects before this, and using this
last object’s TaxCode.
Requirement
10

11. 11
● Logic:
1. For each object from the
FlightOptions array, create one
output object inside the output array.
2. The AppliedTaxCode will contain the
value from the last Connection
object.
3. If the EndOfConnection field is true,
create a separate output object.
4. If there are EndOfConnection fields
that are true and this is not the last
object inside the Connections array,
create a new output object
containing all the false Connection
objects before this, and using this
last object’s TaxCode.
5. Each AppliedConnections object in
the output must have:
1. A hardcoded Type value
“Connection”.
Requirement
11

12. Building the Solution

13. 13
● DW Playground: https://dwl.mule.club/
● Input payload:
{"FlightOptions":[{"Connections":[{"ReferenceID":111,"TaxCode":"ABC","EndOfConnection":false},{"ReferenceID":222,"TaxCode":"DEF","EndOfConnection":true}]},{"
Connections":[{"ReferenceID":333,"TaxCode":"GHI","EndOfConnection":true},{"ReferenceID":444,"TaxCode":"JKL","EndOfConnection":true}]},{"Connections":[{"Ref
erenceID":555,"TaxCode":"MNO","EndOfConnection":false},{"ReferenceID":666,"TaxCode":"PQR","EndOfConnection":false},{"ReferenceID":777,"TaxCode":"STU","
EndOfConnection":false}]},{"Connections":[{"ReferenceID":888,"TaxCode":"VWX","EndOfConnection":false}]},{"Connections":[{"ReferenceID":999,"TaxCode":"MNO"
,"EndOfConnection":false},{"ReferenceID":101,"TaxCode":"PQR","EndOfConnection":true},{"ReferenceID":102,"TaxCode":"STU","EndOfConnection":false}]}]}
● Expected output:
[{"AppliedTaxCode":"DEF","AppliedConnections":[{"Type":"Connection","IndexValue":1},{"Type":"Connection","IndexValue":2}]},{"AppliedTaxCode":"GHI","AppliedCo
nnections":[{"Type":"Connection","IndexValue":3}]},{"AppliedTaxCode":"JKL","AppliedConnections":[{"Type":"Connection","IndexValue":4}]},{"AppliedTaxCode":"STU
","AppliedConnections":[{"Type":"Connection","IndexValue":5},{"Type":"Connection","IndexValue":6},{"Type":"Connection","IndexValue":7}]},{"AppliedTaxCode":"VW
X","AppliedConnections":[{"Type":"Connection","IndexValue":8}]},{"AppliedTaxCode":"PQR","AppliedConnections":[{"Type":"Connection","IndexValue":9},{"Type":"C
onnection","IndexValue":10}]},{"AppliedTaxCode":"STU","AppliedConnections":[{"Type":"Connection","IndexValue":11}]}]
● Format JSONs:
https://jsonformatter.curiousconcept.com/
Building the Solution

14. 14
1) Extract the Connections arrays.
Building the Solution

15. 15
2) Change all the EndOfConnection to true for the last Connection object from the Connections
array.
Building the Solution

16. 16
3) flatten the array of arrays to be just one array.
Building the Solution

17. 17
4) Add a new field to keep track of the object’s index, basing on the EndOfConnection field.
(For each EndOfConnection=true, stop incrementing the index.)
Building the Solution
Index 1
Index 2
Index 1
Index 1
Index 1
Index 3
Index 2

18. 18
5) Add a new field to keep track of the final AppliedConnections object’s (first) index where the
object in question will be added.
Note: This is calculated using the object’s index + 1 (to start at 1) and then minus the previously
added indexBasedOnEOC field.
Building the Solution
Index 0
Index 2
Index 3
Index 4

19. 19
6) Separate the objects based on the EndOfConnection value (true or false).
Building the Solution

20. 20
7) Take only the objects that are inside the “true” list.
Building the Solution

21. 21
8) Create the final output.
Building the Solution

22. Playing with the indexes

23. 23
Playing with the indexes
1
2
1
1
1
2
3
1
1
1
2
Index based on
EndOfConnection

24. 24
Playing with the indexes
Index based on
EndOfConnection index + 1
1
3
4
5
2 6
7
8
9
10
11
1
2
1
1
1
2
3
1
1
1
2

25. 25
Playing with the indexes
Index based on
EndOfConnection
1-1=0
3-1=2
4-1=3
5-1=4
2-2=0 6-2=4
7-3=4
8-1=7
9-1=8
10-2=8
11-1=10
1
2
1
1
1
2
3
1
1
1
2
AppliedConnections
Index
(index+1) - indexBasedOnEOC

26. 26
Playing with the indexes
Index based on
EndOfConnection
0
2
3
4
0 4
4
7
8
8
10
1
2
1
1
1
2
3
1
1
1
2
1+0=1
2+0=2
1+2=3
1+3=4
1+4=5
2+4=6
3+4=7
1+7=8
1+8=9
2+8=10
1+10=11
AppliedConnections
Index
(index+1) - indexBasedOnEOC
IndexValue
indexBasedOnEOC (or actualIndex or
actualNum) +
indexAppliedConnections

27. Try it yourself!

28. Code
● GitHub repository: https://github.com/alexandramartinez/reviewing-a-complex-dw-
transformation-use-case/

29. References
● https://docs.mulesoft.com/mule-runtime/4.3/dataweave-functions
● https://docs.mulesoft.com/mule-runtime/4.3/dataweave-variables
● https://docs.mulesoft.com/mule-runtime/4.3/dataweave-flow-control
● https://docs.mulesoft.com/mule-runtime/4.3/dataweave-selectors
● https://docs.mulesoft.com/mule-runtime/4.3/dataweave-cookbook-defaults
● https://docs.mulesoft.com/mule-runtime/3.9/dataweave-operators
● https://docs.mulesoft.com/mule-runtime/4.3/dw-operators
● https://docs.mulesoft.com/mule-runtime/4.3/dw-core-functions-isempty
● https://docs.mulesoft.com/mule-runtime/4.3/dw-core-functions-reduce
● https://docs.mulesoft.com/mule-runtime/4.3/dw-core-functions-map
● https://docs.mulesoft.com/mule-runtime/4.3/dw-core-functions-groupby
● https://docs.mulesoft.com/mule-runtime/4.3/dw-core-functions-flatten

30. Questions?

31. Quiz…
Go to www.menti.com and use the code 5462238

32. MuleSoft News for November
• There is still time to register and submit a project for the MuleSoft Hackthon 2020! If you
are interested in participating the deadline for register and submit is Nov 29, 2020 at 11:59
pm PT. https://www.mulesoft.com/hackathon2020
• Register and complete the free training course offered by MuleSoft
Anypoint Platform Development: Fundamentals
• The course prepares students to take the MuleSoft Certified Developer - Level 1 (Mule
4) exam. Upon successful completion of the course, students automatically receive two
exam attempts. https://training.mulesoft.com/course/development-fundamentals-mule4
• Try out the new features of Anypoint Studio 7.7! https://docs.mulesoft.com/release-
notes/studio/anypoint-studio-7.7-with-4.3-runtime-release-notes

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