[rules-users] looping in drools
Davide Sottara
dsotty at gmail.com
Mon Mar 10 15:29:08 EDT 2014
You should realize that the LHS ("when") and RHS ("then") are different
and use different syntaxes.
The RHS is essentially java... you can't use ":" and "from".
Also.. "Event(..) from .." is a pattern - a filter that tries to match
existing objects asserted in the WM.
What you need there is to create a new Event.. just do it the way you
would in Java.
You will have to learn to read error messages, too.
What the error is trying to say, is that it interpreted the Event( .. )
statement as a method call,
which is of course undefined.
On 03/10/2014 08:19 PM, Sandhya Sree wrote:
> i tried this :
>
> rule "new file"
> when
> FileData($old : fileOld, $new : fileNew, fileOld != fileNew)
> $newFile : String( this not memberOf $old ) from $new
> then
> event : Event("file added", filename, new Date()) from $plus
> Event.listOfEvents.add(event);
> event.display();
> end
>
>
> this gives the following error:
> The method Event(String, File, Date) is undefined for the type
> Rule_new_file_0c90fff8d9b74b439ab79971b13b75ac
> Syntax error on token "from", ; expected
> $plus cannot be resolved to a type
> Syntax error on token ".", ; expected
> listOfEvents cannot be resolved
>
>
> On Tue, Mar 11, 2014 at 12:09 AM, Davide Sottara <dsotty at gmail.com
> <mailto:dsotty at gmail.com>> wrote:
>
> "from" will iterate for you, exactly like "accumulate" counted the
> events.
> If you need more details, please consult the documentation
>
>
>
> On 03/10/2014 07:29 PM, Sandhya Sree wrote:
>> The problem here is even if multiple files are added, there is
>> only one event object created. i want to have like say if 3 new
>> files are added, 3 event objects must be created, and all three
>> event objects must be added to List<Event> listOfEvents.
>>
>>
>> Thanks.
>>
>>
>> On Mon, Mar 10, 2014 at 11:48 PM, Davide Sottara
>> <dsotty at gmail.com <mailto:dsotty at gmail.com>> wrote:
>>
>> The "accumulates" should not be in the "then" part of a rule
>> (see my previous email).
>> That rule gave you two lists, in the variables $plus and
>> $mins, that you can use in the consequence.
>>
>> If you need to process each file separately, you may want to
>> do something like this:
>>
>> rule "new file"
>> when
>> FileData($old : fileOld, $new : fileNew, fileOld != fileNew)
>> $newFile : String( this not memberOf $old ) from $new
>> then
>> // create new event for a new file : new Event(...)
>> // add to list : Event.listOfEvents.add(...)
>> end
>>
>> You'll need another rule for the files that have been removed.
>>
>> Notice that your Event class has no way to distinguish
>> "added" from "removed" files, you may want to
>> add a boolean or something there.
>> Best
>> Davide
>>
>>
>> On 03/10/2014 07:04 PM, Sandhya Sree wrote:
>>> hi,
>>> im new to drools..im trying to create a project as follows.
>>> i have a class called Monitor which monitors a folder and
>>> creates two lists called fileOld( which is the list of
>>> filenames in that folder at time t1) and fileNew(which is
>>> the list of filenames in that folder at time t2). i have
>>> another class called FileData which contains two members
>>> fileOld and fileNew (list of strings) with getters,setters
>>> and constructor. fileOld and fileNew from Monitor Class are
>>> passed to FileData class.
>>>
>>> i also have another class called Event which is as follows:
>>> public class Event {
>>> public static String name;
>>> private File source;
>>> private Date timeStamp;
>>> public static List<Event> listOfEvents = new
>>> ArrayList<Event>();
>>>
>>> public Event(String name, File source, Date timeStamp) {
>>> this.name <http://this.name> = name;
>>> this.source = source;
>>> this.timeStamp = timeStamp;
>>> }
>>> public String getName() {
>>> return name;
>>> }
>>> public void setName(String name) {
>>> this.name <http://this.name> = name;
>>> }
>>> public File getSource() {
>>> return source;
>>> }
>>> public void setSource(File source) {
>>> this.source = source;
>>> }
>>> public Date getTimeStamp() {
>>> return timeStamp;
>>> }
>>> public void setTimeStamp(Date timeStamp) {
>>> this.timeStamp = timeStamp;
>>> }
>>>
>>> now i have to compare these two lists(fileOld and fileNew)
>>> in a rule file and if they are not equal i have to create an
>>> event object for every file added and deleted and put it in
>>> the List<Event> listOfEvents.
>>>
>>> here is my rule file:
>>>
>>> rrule "files are equal"
>>> when
>>> FileData( fileOld == fileNew)
>>> then
>>> System.out.println("files are equal");
>>> end
>>>
>>>
>>> rule "files not equal"
>>> when
>>> FileData($old : fileOld, $new : fileNew, fileOld != fileNew)
>>>
>>> then
>>> accumulate( $s : String( this not memberOf $old ) from
>>> $new, $plus : collectList( $s ) )
>>> accumulate( $t : String( this not memberOf $new ) from
>>> $old, $mins : collectList( $t ) )
>>> System.out.println("files added:" + $plus );
>>> System.out.println( "files deleted:" + $mins );
>>> end
>>>
>>>
>>>
>>> how can i loop through each of the file added or deleted and
>>> create an Event Class object for every file added and
>>> deleted and finally add all the created objects to
>>> List<Event> listOfEvents..
>>>
>>>
>>> Thanks.
>>>
>>>
>>> _______________________________________________
>>> rules-users mailing list
>>> rules-users at lists.jboss.org <mailto:rules-users at lists.jboss.org>
>>> https://lists.jboss.org/mailman/listinfo/rules-users
>>
>>
>> _______________________________________________
>> rules-users mailing list
>> rules-users at lists.jboss.org <mailto:rules-users at lists.jboss.org>
>> https://lists.jboss.org/mailman/listinfo/rules-users
>>
>>
>>
>>
>> _______________________________________________
>> rules-users mailing list
>> rules-users at lists.jboss.org <mailto:rules-users at lists.jboss.org>
>> https://lists.jboss.org/mailman/listinfo/rules-users
>
>
> _______________________________________________
> rules-users mailing list
> rules-users at lists.jboss.org <mailto:rules-users at lists.jboss.org>
> https://lists.jboss.org/mailman/listinfo/rules-users
>
>
>
>
> _______________________________________________
> rules-users mailing list
> rules-users at lists.jboss.org
> https://lists.jboss.org/mailman/listinfo/rules-users
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.jboss.org/pipermail/rules-users/attachments/20140310/45403c35/attachment-0001.html
More information about the rules-users
mailing list