[rules-users] Alternative for using a regular expression

Dean Whisnant dean at basys.com
Wed Oct 20 15:56:15 EDT 2010


Hello,

In designing our rules system to allow users and analysts to create and edit rules (through Guvnor) we have a requirement that some of the fields be able to be evaluated for specific characters in specific positions of the string.  See the following examples:

Example 1: The string named "claimStatus" contains various flags all pushed together in a string.  It might look like "ABS1324BB7".  Together this field means about nothing, but position 4-7 (1324) is an important code that they want to evaluate. A business rule for this would be if position 4-7 in claimStatus = "1324" then we categorize that claims for some reason.

In loose java syntax I would likely use 'if claimStatus.substring(3,4) = "1324" then do something.

I could have the user program a formula using the substring method, but that would be quite inefficient and a lot of information for them to figure out.

I could have the user say claimStatus matches ^.{4}1324.{0,} but this regular expression is quite cryptic.

While at Rulesfest I ran the topic by a couple folks there and they thought that posing it to the community might be a good idea.  Is there another way you could see doing this?  Is there a DSL format that might get us to where we want?

Ideas that have been thought of included creating a variable that is already just the 4 characters we are after, but there are dozens of fields that could hold this info and that would increase our data model which is already quite verbose.  We also looked at allowing them to create a variable when they need it and then just reuse that in rules, but I'm not certain how we would do this with as many fields.

To add to it, the regular expression I listed is for one of the fields in these streams, we also have needs to pull out other positions as well.

Your thoughts and ideas on this are appreciated.

Thank you!

Dean Whisnant
basys, inc.
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