[rules-users] ClassCastException when comparing date type with literal
Zeke
xanadu860122 at gmail.com
Sat Mar 31 21:54:13 EDT 2012
Thanks for your kindly reply. For the "mitigated restriction", do you mean
I can use Order( eval( $msg.getDate().compareTo( new Date(...) ) ) ) # in
5.2.0 and 5.3.0? Can you give me any example or tell me any manual I can
reference to?
Thank you!
On 31 March 2012 13:06, Wolfgang Laun <wolfgang.laun at gmail.com> wrote:
> On 31/03/2012, Zeke <xanadu860122 at gmail.com> wrote:
> > It is just a test case used to bring up the issue. The real rule
> condition
> > in my business logic is more complex, like
> > Order( id == '...', $msg.date > '...', num == $msg.num ). Of course I can
> > change to use Message as Pattern to work aournd, but it is too tricky,
> > right? And no matter the usage is weird or not, it is legal, right?
> >
>
> I can't really say what was legal in 4.0.7, but
> $msg: Message()
> Order( $msg.date > '...' )
> was not legal in 5.1.1. For any constraint, the left hand side would have
> to
> be a reference to a field of the fact where it occurs.
> Order(Id == '...') # is OK
> You can refer to fields of another fact on the RHS:
> Order(num == $msg.num ) # is OK
> Any other expression would have to be written in clean Java (or MVEL)
> but enclosed in eval()
> Order( eval( $msg.getDate().compareTo( new Date(...) ) == 1 ) ) # or
> similar ;-)
>
> Starting with 5.2.0, this restriction was mitigated and by 5.3.0 and
> certainly in 5.4.0 a wide range of (boolean) expressions is
> acceptable.
>
> However, I should emphasize that postponing the use of a constraint
> into a later pattern is an antipattern for rule coding. Consider
> $msg: Message()
> This matches any fact of type Message, and the Engine must needs keep
> track of this. Contrariwise,
> $msg: Message( date > "...")
> narrows this effort down. Putting a constraint where it belongs is not
> a "workaround", it's best practice :)
>
> -W
>
>
> > I am using Drools 4.0.7. If later release fixes this bug, I may try to
> > upgrade. I don't want to change LHS. It will bring much effort in my
> > project.
> >
> >
> > On 30 March 2012 14:09, FrankVhh <frank.vanhoenshoven at agserv.eu> wrote:
> >
> >> Let me rephrase my question:
> >>
> >> As date is an attribute of message, why don't you use:
> >>
> >> $msg : Message( date > "...")
> >>
> >> Constraining an attribute of Message in the Order pattern seems a weird
> >> thing to do.
> >>
> >>
> >>
> >> Zeke-3 wrote
> >> >
> >> > It seems not work.
> >> > When I try
> >> > *$msg : Message($date : date)
> >> > Order ( $date > "Mar-01-2012" )*
> >> > I meet error "Unable to create Field Extractor for '$date' of
> >> > '[ClassObjectType class=org.drools.examples.HelloWorldExample$Second]'
> >> > in
> >> > rule 'default' : [Rule name=default, agendaGroup=MAIN, salience=0,
> >> > no-loop=false]"
> >> >
> >> > When I try
> >> > *$msg : Message($date : date)
> >> > eval ( $date > "Mar-01-2012" )*
> >> > If the dialect is "java", I meet error "Rule Compilation error : [Rule
> >> > name=default, agendaGroup=MAIN, salience=0, no-loop=false]
> >> > org/drools/examples/test/Rule_default_0.java (8:354) : The
> operator
> >> > >
> >> > is undefined for the argument type(s) Date, String"
> >> > If the dialect is "mvel", I meet the same ClassCastException.
> >> >
> >> > On 29 March 2012 22:28, FrankVhh <frank.vanhoenshoven@> wrote:
> >> >
> >> >> This may sound a bit rude, but... why would you want to do such a
> >> >> thing?
> >> >>
> >> >> If there is a constraint on the message, then why not put that
> >> constraint
> >> >> in
> >> >> the message structure?
> >> >>
> >> >> Btw, I think it would work by using eval($date < "...") but see no
> use
> >> >> for
> >> >> it either.
> >> >>
> >> >>
> >> >> Joe Zendle wrote
> >> >> >
> >> >> > did you try:
> >> >> >
> >> >> > *$msg : Message($date : date)
> >> >> > Order ( $date > "Mar-01-2012" )*
> >> >> >
> >> >> >
> >> >> >
> >> >> > 2012/3/29 Zeke <xanadu860122@>
> >> >> >
> >> >> >> Hi, guys:
> >> >> >> I meet a strange issue and need your help again... I am using
> >> Drools
> >> >> >> 4.0.7.
> >> >> >> When my rule condition is as *Message( date > "Mar-01-2012" )*,
> >> >> >> everything is OK. But if I change it to be as below:
> >> >> >> *$msg : Message()
> >> >> >> Order ( $msg.date > "Mar-01-2012" )*
> >> >> >> I will meet "java.lang.String cannot be cast to java.util.Date"
> >> >> >> ClassCastException. "Order" is another fact. I attach the
> exception
> >> >> call
> >> >> >> stack. Please check it. It looks like a bug to me. Do we fix it in
> >> >> later
> >> >> >> release? If so, can you tell me which release contains the fix?
> >> >> Thanks!
> >> >> >>
> >> >> >> _______________________________________________
> >> >> >> rules-users mailing list
> >> >> >> rules-users at .jboss
> >> >> >> https://lists.jboss.org/mailman/listinfo/rules-users
> >> >> >>
> >> >> >>
> >> >> >
> >> >> > _______________________________________________
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> >> >> >
> >> >>
> >> >>
> >> >> --
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> >> >>
> >>
> http://drools.46999.n3.nabble.com/rules-users-ClassCastException-when-comparing-date-type-with-literal-tp3867229p3867832.html
> >> >> Sent from the Drools: User forum mailing list archive at Nabble.com.
> >> >> _______________________________________________
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> >>
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