Overriding default query listener ,field validation of af:query- Oracle ADF

Hello All,

this post talks about a common requirement - can we apply custom validation in af:query fields ? yes , we can do that by overriding default query listener of af:query component

What af:query is ?

see- Oracle Docs-af:query

"The query component provides the user the ability to perform a query based on a saved search or personalize saved searches. The component displays a search panel with various elements, each of which help the user to accomplish various tasks."

Follow steps to apply validation on af:query-

• Here i am taking example of Departments table of HR Schema
• First create business components for Departments table

• then create  bind variables and a view-criteria in departments view object
  
  
  
  
  
• See the view criteria is applied for LocationId, ManagerId and Department Name

• Now create a page and drop criteria with table on page- it will look like this

• Next is to select af:query on page and go to property inspector and copy text of default query listener

• Now create a managed bean and create a custom query listener for af:query
  
  
  
   
• In this custom query listener , in this example i am checking for negative Location Id and Manager Id, if there is any negative values ,custom method will show a message otherwise default queryListener will be executed
• We can get af:query's components value using 2 methods
  First One  - Using Bind Variable (getNamedWhereClauseParam)
  Second One - Using QueryDescriptor and ConjunctionCriterion
• I'm going to explain both methods - see code of custom query listener using first method, two generic methods will be used in this process to invoke expression language and to get BindingContainer of current context



    /**Method to invoke EL Expression
     * @param el
     * @param paramTypes
     * @param params
     * @return
     */
    public static Object invokeEL(String el, Class[] paramTypes, Object[] params) {
        FacesContext facesContext = FacesContext.getCurrentInstance();
        ELContext elContext = facesContext.getELContext();
        ExpressionFactory expressionFactory = facesContext.getApplication().getExpressionFactory();
        MethodExpression exp = expressionFactory.createMethodExpression(elContext, el, Object.class, paramTypes);

        return exp.invoke(elContext, params);
    }

    /**Method to get Binding Container of current page
     * @return
     */
    public BindingContainer getBindings() {
        return BindingContext.getCurrent().getCurrentBindingsEntry();
    }



• See the first method to get af:query components value and validate that



    /**Custome Query Listener- Using getNamedWhereClauseParam
     * @param queryEvent
     */
    public void customQueryListener(QueryEvent queryEvent) {
        String deptName = null;
        Integer locId = null;
        Integer mgrId = null;

        /**Get Iterator of Table*/
        DCIteratorBinding iter = (DCIteratorBinding)getBindings().get("DepartmentsView1Iterator");

        /**Get ViewObject from Iterator*/
        ViewObjectImpl vo = (ViewObjectImpl)iter.getViewObject();

        /**Get Bind Variable's Value*/
        if (vo.getNamedWhereClauseParam("LocIdBind") != null) {
            locId = Integer.parseInt(vo.getNamedWhereClauseParam("LocIdBind").toString());
        }
        if (vo.getNamedWhereClauseParam("MgrIdBind") != null) {
            mgrId = Integer.parseInt(vo.getNamedWhereClauseParam("MgrIdBind").toString());
        }
        if (vo.getNamedWhereClauseParam("DeptNmBind") != null) {
            deptName = vo.getNamedWhereClauseParam("DeptNmBind").toString();
        }

        /**Check for Negative values*/
        if ((locId != null && locId < 0) || (mgrId != null && mgrId < 0)) {
            FacesMessage msg = new FacesMessage("Id Value can not be negative");
            msg.setSeverity(FacesMessage.SEVERITY_ERROR);
            FacesContext.getCurrentInstance().addMessage(null, msg);
        } else {
            /**Execute default query listener with help of invokeEL method*/

            invokeEL("#{bindings.DepartmentsViewCriteriaQuery.processQuery}", new Class[] { QueryEvent.class },
                     new Object[] { queryEvent });
        }
    }



• And Second Method using QueryDescriptor is-



    /**Custom Query Listener-Using QueryDescriptor
     * @param queryEvent
     */
    public void customqueryProcess(QueryEvent queryEvent) {
        String deptName = null;
        Integer locId = null;
        Integer mgrId = null;

        /**Reference-Frank Nimphius Example- ADF Code Corner
       * http://www.oracle.com/technetwork/developer-tools/adf/learnmore/85-querycomponent-fieldvalidation-427197.pdf
       * */
        QueryDescriptor qd = queryEvent.getDescriptor();

        ConjunctionCriterion conCrit = qd.getConjunctionCriterion();
        //access the list of search fields
        List<Criterion> criterionList = conCrit.getCriterionList();
        //iterate over the attributes to find FromDate and ToDate
        for (Criterion criterion : criterionList) {
            AttributeDescriptor attrDescriptor = ((AttributeCriterion)criterion).getAttribute();

            if (attrDescriptor.getName().equalsIgnoreCase("DepartmentName")) {
                deptName = (String)((AttributeCriterion)criterion).getValues().get(0);

            } else {
                if (attrDescriptor.getName().equalsIgnoreCase("LocationId")) {
                    locId = (Integer)((AttributeCriterion)criterion).getValues().get(0);

                }
            }
            if (attrDescriptor.getName().equalsIgnoreCase("ManagerId")) {
                mgrId = (Integer)((AttributeCriterion)criterion).getValues().get(0);

            }
        }
        if ((locId != null && locId < 0) || (mgrId != null && mgrId < 0)) {
            FacesMessage msg = new FacesMessage("Id Value can not be negative");
            msg.setSeverity(FacesMessage.SEVERITY_ERROR);
            FacesContext.getCurrentInstance().addMessage(null, msg);
        } else {
            /**Process default query listener*/
            invokeEL("#{bindings.DepartmentsViewCriteriaQuery.processQuery}", new Class[] { QueryEvent.class },
                     new Object[] { queryEvent });
        }

    }



• Now Run your application and check it for negative values

Cheers- Download Sample App Happy Learning :-)