Solution will make use of the following: 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 (>>)

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

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• 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:

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• Input JSON structure:
– FlightOptions (array of objects)
• Connections (array of objects)
– ReferenceID (number)
– TaxCode (string)
– EndOfConnection (Boolean)
Requirement

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• Input JSON structure:
– FlightOptions (array of objects)
• Connections (array of objects)
– ReferenceID (number)
– TaxCode (string)
– EndOfConnection (Boolean)
• Output JSON structure:
– Array of objects
• AppliedTaxCode (string – from TaxCode)
• AppliedConnections (array of objects)
– Type (string – hardcoded value “Connection”)
– IndexValue (number - dynamic)
Requirement

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

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• 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

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• 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, even
though the Connection might be inside
a FlightOption object.
Requirement

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• 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, even
though the Connection might be inside
a FlightOption 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 object’s TaxCode.
Requirement

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• 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, even though the
Connection might be inside a FlightOption 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 object’s TaxCode.
5. For each object from the Connections array
(taking into account the EndOfConnection
true/false logic), create one AppliedConnections
object with:
1. a hardcoded Type value ”Connection”
2. an incrementing IndexValue throughout the
complete output.
Requirement

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• Examples per FlightOptions object:
– 1) EndOfConnection: false
– 2) EndOfConnection: true
Requirement
• Output:
– 1 object containing
– 2 AppliedConnections objects

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• Examples per FlightOptions object:
– 1) EndOfConnection: true
– 2) EndOfConnection: true
Requirement
• Output:
– 2 objects containing
– 1 AppliedConnections object each

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• Examples per FlightOptions object:
– 1) EndOfConnection: false
– 2) EndOfConnection: false
– 3) EndOfConnection: false
Requirement
• Output:
– 1 object containing
– 3 AppliedConnections objects

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• Examples per FlightOptions object:
– 1) EndOfConnection: false
• Note: if this was true, it would
behave the same
Requirement
• Output:
– 1 object containing
– 1 AppliedConnections object

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• Examples per FlightOptions object:
– 1) EndOfConnection: false
– 2) EndOfConnection: true
– 3) EndOfConnection: false
Requirement
• Output:
– 2 objects.
• First: 2 AppliedConnections objects
• Second: 1 AppliedConnections object

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• DW Playground: https://dwl.mule.club/
• Input payload:
{"FlightOptions":[{"Connections":[{"ReferenceID":111,"TaxCode":"ABC","EndOfConnection":false},{"ReferenceID":222,"TaxCode":"DEF","EndOfConnection":true}]},{"C
onnections":[{"ReferenceID":333,"TaxCode":"GHI","EndOfConnection":true},{"ReferenceID":444,"TaxCode":"JKL","EndOfConnection":true}]},{"Connections":[{"Refere
nceID":555,"TaxCode":"MNO","EndOfConnection":false},{"ReferenceID":666,"TaxCode":"PQR","EndOfConnection":false},{"ReferenceID":777,"TaxCode":"STU","EndOfC
onnection":false}]},{"Connections":[{"ReferenceID":888,"TaxCode":"VWX","EndOfConnection":false}]},{"Connections":[{"ReferenceID":999,"TaxCode":"MNO","EndOfC
onnection":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","AppliedCon
nections":[{"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":"VWX"
,"AppliedConnections":[{"Type":"Connection","IndexValue":8}]},{"AppliedTaxCode":"PQR","AppliedConnections":[{"Type":"Connection","IndexValue":9},{"Type":"Conn
ection","IndexValue":10}]},{"AppliedTaxCode":"STU","AppliedConnections":[{"Type":"Connection","IndexValue":11}]}]
• Format JSONs for better view:
https://jsonformatter.curiousconcept.com/
Building the Solution

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• 1) Extract the Connections arrays.
Building the Solution

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

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

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• 4) Add a new field to keep track of the object’s index, basing on the
EndOfConnection field.
– (i.e. 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

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• 5) Add a new field to keep track of the final AppliedConnections
object’s (first) index where the object in question will be added.
– 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

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

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

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• 8) Create the final output
Building the Solution

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• Playing with the indexes
Index based on
EndOfConnection
1
2
1
1
1
2
3
1
1
1
2

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

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• Playing with the indexes
AppliedConnections
Index
(index+1) - indexBasedOnEOC
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
Index based on
EndOfConnection
1
2
1
1
1
2
3
1
1
1
2

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• Playing with the indexes
AppliedConnections
Index
(index+1) - indexBasedOnEOC
IndexValue
indexBasedOnEOC (or
actualIndex or actualNum) +
indexAppliedConnections
0
2
3
4
0 4
4
7
8
8
10
Index based on
EndOfConnection
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

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• Github repository: https://github.com/alexandramartinez/reviewing-
a-complex-dw-transformation-use-case/
Code

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• 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
References

30. Questions?