Actionable Dynamic Queries

Suppose you have over a million users, and you want to perform some kind of mass update to some of them. One approach might be to use a dynamic query to retrieve the list of users in question. Once loaded into memory, you could loop through the list and update each user. However, with over a million users, the memory cost of such an operation would be too great. In general, retrieving large numbers of Service Builder entities using dynamic queries requires too much memory and time.

Liferay actionable dynamic queries solve this problem. Actionable dynamic queries use a pagination strategy to load only small numbers of entities into memory at a time and perform processing (i.e., perform an action) on each entity. So instead of trying to use a dynamic query to load a million users into memory and then perform some processing on each of them, a much better strategy is to use an actionable dynamic query. This way, you can still process your million users, but only small numbers are loaded into memory at a time.

Here’s how to use actionable dynamic query:

1. Get an ActionableDynamicQuery from your *LocalService by invoking its getActionableDynamicQuery method.

2. Add query criteria and constraints, using the query’s setAddCriteriaMethod and setAddOrderCriteriaMethod methods.

3. Set an action to perform on the matching entities, using setPerformActionMethod.

4. Execute the action on each matching entity, by invoking the query’s performActions method.

This method from a sample portlet creates an actionable dynamic query, adds a query restriction and an action, and executes the query:

protected void massUpdate() {
    ActionableDynamicQuery adq = _barLocalService.getActionableDynamicQuery();
    
    adq.setAddCriteriaMethod(new ActionableDynamicQuery.AddCriteriaMethod() {
        
        @Override
        public void addCriteria(DynamicQuery dynamicQuery) {
            dynamicQuery.add(RestrictionsFactoryUtil.lt("field3", 100));
        }
        
    });
    
    adq.setPerformActionMethod(new ActionableDynamicQuery.PerformActionMethod<Bar>() {
        
        @Override
        public void performAction(Bar bar) {
            int field3 = bar.getField3();
            field3++;
            bar.setField3(field3);
            _barLocalService.updateBar(bar);
        }
        
    });
    
    try {
        adq.performActions();
    }
    catch (Exception e) {
        e.printStackTrace();
    }
}

The example method demonstrates executing an actionable dynamic query on Bar entities that match certain criteria.

1. Retrieve an ActionableDynamicQuery from local service BarLocalService.

   ActionableDynamicQuery adq = _barLocalService.getActionableDynamicQuery();
   

   Note: Service Builder generates method getActionableDynamicQuery() in each entity’s *LocalService interface and implements it in each entity’s *BaseLocalServiceImpl class.

   @Transactional(propagation = Propagation.SUPPORTS, readOnly = true)
   public ActionableDynamicQuery getActionableDynamicQuery();
   

2. Set query criteria to match field3 values less than 100.

   adq.setAddCriteriaMethod(new ActionableDynamicQuery.AddCriteriaMethod() {
   
        @Override
        public void addCriteria(DynamicQuery dynamicQuery) {
            dynamicQuery.add(RestrictionsFactoryUtil.lt("field3", 100));
        }
   
    });
   

3. Set an action to perform. The action increments the matching entity’s field3 value.

   adq.setPerformActionMethod(new ActionableDynamicQuery.PerformActionMethod<Bar>() {
   
        @Override
        public void performAction(Bar bar) {
            int field3 = bar.getField3();
            field3++;
            bar.setField3(field3);
            _barLocalService.updateBar(bar);
        }
   
    });
   

4. Execute the action on each matching entity.

   try {
       adq.performActions();
   }
   catch (Exception e) {
       e.printStackTrace();
   }
   

Actionable dynamic queries let you act on large numbers of entities in smaller groups. It’s an efficient and high performing way to update entities.

Related Topics

Creating Local Service

Invoking Local Services