Reviewing a complex dataweave transformation use case v3

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

2. 2
● Modules (Values module)
● Functions (fun)
○ Parameters using types
○ Parameters with default values
○ Tail Recursive
● 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, with
○ Sum (+), Append (+), Concatenation (++), Equality with coercion (~=)
Solution will make use of the following:

3. Requirement

4. 4
Input JSON structure to Output JSON structure
Requirement

5. 5
● Logic:
1. For each object from the
FlightOptions array, create one
output object inside the output array.
Requirement
5

6. 6
● 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
6

7. 7
● 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
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.
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
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.
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
9

10. Building the Solution

11. 11
● DW Playground: https://dwlang.fun
● 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

12. 12
1) Extract the Connections arrays.
Building the Solution

13. 13
2) Change all the EndOfConnection to true for the last Connection object from the Connections
array.
Building the Solution

14. 14
3) flatten the array of arrays to be just one array.
Building the Solution

15. 15
4) Parameters:
1. connectionsArray - Current connections array (this will have less values each time, until array is
empty).
2. indexAccumulatorArray - Array with the indexes that are being accumulated for the ”IndexValue”
field.
3. index - Actual index number for each connection being evaluated.
4. connectionsAccumulatorArray - Array that will keep the transformed objects (final output) – This is
what makes our function a tail function.
Building the Solution – Tail Recursive function

16. 16
Iteration 1:
Building the Solution – Tail Recursive function
connectionsArray (original array) indexAccumulatorArray
index
connectionsAccumulatorArray
thisConnection
EndOfConnection = false
Nothing is added to
connectionsAccumulatorArray
Next connection
indexAccumulatorArray should
contain this index
because
thisConnectionEndOfConnection
is false.

17. 17
Iteration 2:
Building the Solution – Tail Recursive function
connectionsArray (original array) indexAccumulatorArray
index
connectionsAccumulatorArray
thisConnection
EndOfConnection = true
Object is added to
connectionsAccumulatorArray
Next connection
indexAccumulatorArray should go
back to [ ] because
thisConnectionEndOfConnection
is true.

18. 18
Iteration 3:
Building the Solution – Tail Recursive function
connectionsArray (original array) indexAccumulatorArray
index
connectionsAccumulatorArray
thisConnection
EndOfConnection = true
Object is added to
connectionsAccumulatorArray
Next connection
indexAccumulatorArray should go
back to [ ] because
thisConnectionEndOfConnection
is true.

19. 19
Iteration 4:
Building the Solution – Tail Recursive function
connectionsArray (original array) indexAccumulatorArray
index
connectionsAccumulatorArray
thisConnection
EndOfConnection = true
Object is added to
connectionsAccumulatorArray
Next connection
indexAccumulatorArray should go
back to [ ] because
thisConnectionEndOfConnection
is true.

20. 20
Iteration 5:
Building the Solution – Tail Recursive function
connectionsArray (original array) indexAccumulatorArray
index
connectionsAccumulatorArray
thisConnection
EndOfConnection = false
Nothing is added to
connectionsAccumulatorArray
Next connection
indexAccumulatorArray should
contain this index
because
thisConnectionEndOfConnection
is false.

21. 21
Iteration 6:
Building the Solution – Tail Recursive function
connectionsArray (original array) indexAccumulatorArray
index
connectionsAccumulatorArray
thisConnection
EndOfConnection = false
Nothing is added to
connectionsAccumulatorArray
Next connection
indexAccumulatorArray should
contain this index
because
thisConnectionEndOfConnection
is false.

22. 22
Iteration 7:
Building the Solution – Tail Recursive function
connectionsArray (original array) indexAccumulatorArray
index
connectionsAccumulatorArray
thisConnection
EndOfConnection = true
Object is added to
connectionsAccumulatorArray
Next connection
indexAccumulatorArray should go
back to [ ] because
thisConnectionEndOfConnection
is true.

23. 23
Iteration 8:
Building the Solution – Tail Recursive function
connectionsArray (original array) indexAccumulatorArray
index
connectionsAccumulatorArray
thisConnection
EndOfConnection = true
Object is added to
connectionsAccumulatorArray
Next connection
indexAccumulatorArray should go
back to [ ] because
thisConnectionEndOfConnection
is true.
To be continued… 

24. Try it yourself!

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

26. 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/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-plusplus
● https://blogs.mulesoft.com/dev-guides/how-to-tutorials/untie-multilevel-
structures-dataweave-recursive-calls/

27. Questions?

28. Contact me!
Website:
www.alexandramartinez.world
LinkedIn:
www.linkedin.com/in/alexandra-n-martinez
Twitter:
@alexmartinez_z
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