Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p>To compare dates, you can simply use Drools Fusion's temporal operators (after, before, etc.):</p> <pre><code>when MyClass( myDate after $someOtherDate ) then ... </code></pre> <p>However, there is another problem with your approach: you should not reason against a global in a condition. See the Expert manual <a href="http://docs.jboss.org/drools/release/5.4.0.Beta2/drools-expert-docs/html/ch05.html#d0e3313" rel="noreferrer">section</a> on globals.</p> <p>The notion of "now" is a bit problematic in Drools. Actually, maybe "problematic" isn't the right word; let's go with "tricky". How you represent it depends heavily on your use case. I'll try to summarize:</p> <ul> <li>If you are executing within a stateless session, then your approach will work in combination with the Fusion operators. It is still not a recommended practice, however. A better approach is to define a fact, call it <code>Now</code>, which contains a single <code>Date</code> field. Initialize and insert it along with your other facts then reason against it instead of a global.</li> <li>If you have a stateful session, it gets more tricky because real time is passing even while the session is idle, meaning your <code>Now</code> fact is getting more and more out of date. The way we have solved this is via the use of a <code>WorkingMemoryEventListener</code>. We use the <code>objectInserted</code>, <code>objectRetracted</code>, and <code>objectUpdated</code> methods of this listener to keep our <code>Now</code> fact current (we do not care about precision less than one minute so we check whether a minute has passed from the last update to avoid unnecessary overhead). Rules won't evaluate if working memory isn't changing, so using this listener is sufficient to ensure that <code>Now</code> is updated when it needs to be (unless you have queries that depend on the current value of <code>Now</code>, but that's another topic).</li> <li>You could also look into using Drools Fusion in STREAM mode, which has a notion of "now", but also imposes a few other requirements. See the <a href="http://docs.jboss.org/drools/release/5.4.0.Beta2/drools-fusion-docs/html/" rel="noreferrer">Fusion docs</a> for more information.</li> </ul>
    singulars
    1. This table or related slice is empty.
    1. POuse java.util.Date in a rule's LHS
      singulars
      1. PTQuestion
    1. PTAnswer
    1. This table or related slice is empty.
    1. USmike9322
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. POuse java.util.Date in a rule's LHS
      singulars
      1. PTQuestion
    1. This table or related slice is empty.
    1. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTAcceptedByOriginator
    3. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    1. COYou are mostly correct mike9322 in the sense that the clock should be a fact and not a global. You can use your "Now" class or you can simply use the SessionClock provided by Drools. The PseudoSessionClock fixes most of the problems you mention. In cases where you have flow of time, then it is definitively recommended that you use the STREAM processing mode.
      singulars
      1. PO
      1. USEdson Tirelli
    2. CO@mike9322 thanks for the suggestions from both of you, I've assured that the currentDate in my code is constant and immutable.As the expert manual mentioned.Although not seemingly to be a good way, I think it's working correctly.I'm going to try the way you suggested soon, my questions will be posted here if you'd like.Thanks very much!
      singulars
      1. PO
      1. USSoutheast
    3. COUnfortunately doesn't work on my case, somehow it throws org.drools.RuntimeDroolsException: Conversion to long not supported for type: class java.util.Date
      singulars
      1. PO
      1. USHendy Irawan
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload