[rules-users] looping in drools

[Sandhya Sree]

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> 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> 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 = name;
>>  this.source = source;
>>  this.timeStamp = timeStamp;
>>  }
>>    public String getName() {
>>  return name;
>>  }
>>  public void setName(String name) {
>>  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.
>>
>>
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