Sorting List of Objects in DMN

[Ravi Mangalagiri]

Hi,

I need to sort a list of objects based on a complex compare bkm function.

input: list of objects

bkm function: sortObject(p1, p2) returns 0,1,-1 (just like comparator java method)

my decision:

sort(ctx, list, precedes) work?

what is the context here?

Thanks

Ravi Mangalagiri
703-505-4240 (c)

[Matteo Mortari]

Hi Ravi,

without a DMN model is a bit difficult to give you a 100% valid answer, but the sort() function is defined as:

sort( list, precedes )

You say you have a BKM with signature: sortObject(p1, p2) r

in other words a BKM with 2 parameters as input,

You say you have a list of objects, I call it `mylist`, then it could be:

sort( mylist, function(x,y) sortObject(x, y) )

or even just

sort( mylist, sortObject )

where

`mylist` could be:

[ { name : "John", age: 47}, { name : "Alice", age : 21 } ]

and `sortObject( p1, p2)` could be the bkm defined as:

p1.age < p2.age

Hope this helps,

MM

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[Ravi Mangalagiri]

Let me try and post the DMN

Thanks for quick response Matteo

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[Matteo Mortari]

Glad to help

Please find attached demonstration of the generic use case I mentioned,

works as described: Alice in the `Decision-1` node is before John

Hope this helps,

MM

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[Ravi Mangalagiri]

Matteo,

I spent a day on this and I am not sure what am I missing. The java sort seems to be working perfectly, while the exact code in dmn does not work.

I tweaked the same example, please take a look at the attached example, 

actual order: 1, 2, 3, 4

expected order: 3, 4, 1, 2

java code order: 3, 4, 1, 2 [as expected]

dmn order : 4, 3, 2, 1 (I tried to code the exact logic implemented in java)

Can you take a look, if the sort bkm function implementation is right?

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Ravi Mangalagiri
703-505-4240 (c)

[Matteo Mortari]

Hi Ravi,

you might have inadvertently misunderstood the semantic of the FEEL sort() builtin function, the comparator function works ~like SQL, and should return a boolean.

You can solve your business/domain problem by rewriting your bkm sorting comparator, something ~like: (screenshot attached)

It would return 3-4-1-2 as you expect:

Decision-1: [{id=3, name=Ravi, type=student, age=33, accountBalance=900}, {id=4, name=Henry, type=student, age=26, accountBalance=2500}, {id=1, name=John, type=student, age=25, accountBalance=5000}, {id=2, name=Alice, type=professor, age=47, accountBalance=350}]

Hope this helps!

MM 

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[Ravi Mangalagiri]

Ok that explains. Great! It works.

Thanks

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[Matteo Mortari]

Glad to hear that solved it !

Thanks for the confirmation,

MM

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