[rules-users] Dynamic property names...

[jdepaul]

Hi all - 

I have the following challenge with data mapping.  I'm trying to decide if
DROOLS is the appropriate solution to this problem - please help me decide.

I have a Source object and Target object.  Both objects have the same field
names - the goal is to map data across from Source object to Target object
by apply a set of rules to object's fields.  More than one rule may need to
be activated for each field.  Results of previous mapping operation may
affect later mapping operations further 'downstream' - so it's important to
process fields in a specific sequence and for each field evaluate rules in a
specific order - (not sure, can rule Salience accomplish both?)

About the rules:  There may be several rules in affect for each field -
which must be executed in specific order top to bottom.  Rules should be
applied until the target field is mapped - until the target field is
non-blank.  Same rule may be applied to more than one field from the Source
object.  Rules will be maintain by a Customer Service Reps and will change
periodically.

I would envision the rule setup to be something like this:
  
Rule "Setup variables"
    when 
            $source : SOURCE (rec_type == "PARTNER", $s_loc : location,
$s_op : operator, $s_wo : workorder)
            $target : TARGET  ($t_loc : location, $t_op : operator, $t_wo :
workorder)
    then 
           <do nothing>
end

# Simple mapping for Location field...
rule "Location"
    when
               $target($t_loc == "")  // if blank
    then
               $target.setLocation($s_loc);
               modify($target);
end

# Simple mapping for Operator field...
rule "Operator"
    when
               $target($t_op == "")  // if blank...
    then
               $target.setLocation($s_op);
               modify($target);
end

... rules continue for the rest of the fields...  There are about 150-200
fields to map.  Some rules will define simple straight across mappings,
other rules will need to fetch values from objects from DB (using 'from'
keyword).   Here are some questions:

1)  Opinion please:  Would the outlined approach work in this case given the
number of fields to process and the required sequence for processing.  Seems
that rule management may be a bit difficult...

2)  Is there a way to define functions that could take field names, and then
apply common operations using dynamic field names - i.e. function
simple_map(fieldName) would source data from Source.fieldName and map it to
Tartget.fieldName  - this would require that get/set methods be dynamic - is
that possible?

3)  Is there another approach that would be better suited in this case that
you'd recommend?

Thanks,
James









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