Sunday, July 17, 2011

Error Handling ADF

Created a custom error handler to customize any exceptions that come along. (We throw message keys from the model layer and handle them auto-magically in the handler).

Create an exception handler class.

Add the attribute ErrorHandlerClass  to the root Application tag to DataBindings.cpx ErrorHandlerClass="za.co.transcode.adf.mdm.model.messages.ReferenceCustomMessageHandler".

NOTE: This is not production ready code and needs a few performance tweaks but you will get the idea. This is in our common project you would just override this class in the dependant projects with skipLists and overrideList populated (skipList = {{"java.lang.NullPointerException", null}, {"java.sql.SQLException", "1234"}} OR overrideList = {{"java.lang.SQLException", "9999", "This should never happen"}} )

Code for custom handler:

package za.co.transcode.adf.common.model.messages;

import java.sql.SQLException;

import oracle.adf.model.BindingContext;
import oracle.adf.model.binding.DCErrorHandlerImpl;

import oracle.jbo.JboException;

import za.co.transcode.adf.common.exception.MessageBaseException;
import za.co.transcode.adf.common.util.MessageBundleUtil;


public class CustomMessageHandler extends DCErrorHandlerImpl {
  private String[][] skipList = null;
  private String[][] overrideList = null;

  public CustomMessageHandler() {
    this(true);
  }
  public CustomMessageHandler(boolean setToThrow) {
    super(setToThrow);
  }

  public CustomMessageHandler(String[][] skipList, String[][] overrideList) {
    this(true, skipList, overrideList);
  }

  public CustomMessageHandler(boolean setToThrow, String[][] skipList, String[][] overrideList) {
    this(setToThrow);
    this.setSkipList(skipList);
    this.setOverrideList(overrideList);
  }

  public String getDisplayMessage(BindingContext context, Exception exception) {

    if(isInSkipList(exception)) {
      return null;
    }

    String overrideMessage = overrideMessage(exception);
    if(overrideMessage != null) {
      return overrideMessage;
    }

    String message = super.getDisplayMessage(context, exception);
    return message;
  }

  private boolean isInSkipList(Exception exception) {
    if(getSkipList() != null) {
      for(String[] skip : getSkipList()) {
        if(skip != null && skip.length == 2) {
          String className = skip[0];
          String itemCode = skip[1];

          if(matchClass(exception.getClass(), className) && matchItem(exception, itemCode)) {
            return true;
          }
        }
      }
    }
    return false;
  }

  private String overrideMessage(Exception exception) {
    if(exception instanceof MessageBaseException) {
      return MessageBundleUtil.getMessage(getMessageBundle(), exception.getMessage(),
          ((MessageBaseException) exception).getProperties());

    }
    if(getOverrideList() != null) {
      for(String[] override : getOverrideList()) {
        if(override != null && override.length == 3) {
          String className = override[0];
          String itemCode = override[1];
          String message = override[2];

          if(matchClass(exception.getClass(), className) && matchItem(exception, itemCode)) {
            if(exception instanceof SQLException) {
              message = MessageBundleUtil.formatMessage(message, ((SQLException) exception).getErrorCode());
            }

            return message;
          }
        }
      }
    }
    return null;
  }

  private boolean matchClass(Class exceptionClass, String className) {
    if(className == null) {
      return true;
    }

    try {
      Class clazz = Class.forName(className);
      if(clazz.isAssignableFrom(exceptionClass)) {
        return true;
      }
    } catch(Throwable t) {
      return false;
    }
    return false;
  }

  private boolean matchItem(Exception exception, String overrideCode) {
    if(overrideCode == null) {
      return true;
    }

    try {
      if(exception instanceof SQLException) {
        SQLException sqlException = (SQLException) exception;
        if(String.valueOf(sqlException.getErrorCode()).equalsIgnoreCase(overrideCode)) {
          return true;
        }
      }

      if(exception.getMessage() != null && exception.getMessage().matches(overrideCode)) {
        return true;
      }
    } catch(Throwable t) {
      return false;
    }
    return false;
  }

  protected String[][] getSkipList() {
    return skipList;
  }

  protected void setSkipList(String[][] skipList) {
    this.skipList = skipList;
  }

  protected String[][] getOverrideList() {
    return overrideList;
  }

  protected void setOverrideList(String[][] overrideList) {
    this.overrideList = overrideList;
  }

  protected String getMessageBundle() {
    return MessageBundleUtil.DEFAULT_BUNDLE_NAME;
  }
}


NOTE: when using OperationBindings from the view layer when your method throws and exception the method is stopped as you would expect but your execpetion is  then swallowed by ADF Error handling - so it is your responsibility to check the operations error messages post execute.

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