[rules-users] Writing rules using java from template

[Marcus Ilgner]

2009/3/31 Meny Kobel <meny.kobel at gmail.com>:
> Hi,
> First - Thanks for your quick response.
> Second - As I wrote rules conditions are saved in DB.
>
> Conditions table example :
>
>
> TypeName    Operation       Value                Return Value
> Var1                 >=                5                        “Segment
> 1”
> Var2                 matches      “someString”        “Segment 1”
> Var3                 <                  6                        “Segment
> 1”
> Var4                  ==               1                        “Segment
> 2”
> Var5                  ==                5                       “Segment
> 2”
>
> The table above should trasform to the following DRL rule -
>
> rule "example 1"
>     when
>
>         Bean(var1 >= 5 ,var2 matches "someString",var3 < 6)
>
>     then
>         list.add("Segment 1");
> End
>
> rule "example 2"
>     when
>         Bean(var4 == 1 ,var5 == 5)
>     then
>         list.add("Segment 2");
> End
>
> The conditions are dynamically build on Site by customer and I don’t know
> the number of conditions And the conditions values(the values of columns
> TypeName,Operation, Value and Return Value ).
>
> On Tue, Mar 31, 2009 at 2:35 PM, Meny Kobel <meny.kobel at gmail.com> wrote:
>>
>> Hi,
>> Any updates regarding this subject?
>> I have the same problem and can't find a solution.
>> Like newbie I need to read varying rules from DB and transform them to
>> drools language.
>>
>> Thanks,
>> Meny
>

Hi,

since you seem to have a concrete idea on how your rules should look,
you can simply render them into a String according to your
specification and then pass a StringReader to
PackageBuilder.addPackageFromDrl(). The resultig package can then be
added to your rulebase.
Of course you could also use rules to generate the rules from the
conditions in the DB, which would be more complex but more extensible,
too.

HTH
Marcus