[rules-users] modifying the problem facts while running the solver - Drools Planner

[ge0ffrey]

spinjala wrote
> 
> Once the solver finds that a workorder (WO1) couldn't be assigned to any
> resource in the list of resources (due to the constraints), it simply
> picks up the 1st resource in the list with highest hard score and assigns
> it (even though this assignment breaks all constraints). My question is,
> why is it generating a solution by assigning the wrong resource to the
> workorder instead of say, throwing a message saying this workorder cannot
> be assigned to a resource or something like that. In my opinion, a solver
> should generate a solution only when it is possible to generate but not
> just assign something that has highest score. I may be wrong but would
> really appreciate if you can help here, i am unable to proceed further in
> evaluating this product for my project.
> 

Planner perceives an planning variable with the planning value as being
"uninitialized", not as "unassigned". This is due to
https://issues.jboss.org/browse/JBRULES-3317

Add a planning value resource that represents "unassigned". Then add a hard
constraint rule that gets trigged if something is assigned to that planning
value. Give a lower weight than 2 entities being assigned to the same value
and make the 2 entities being assigned to the same value not trigger if they
are assigned to that "unassigned" value.



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