org.gwtbootstrap3.client.ui.form.error.DefaultErrorHandler.java Source code

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Here is the source code for org.gwtbootstrap3.client.ui.form.error.DefaultErrorHandler.java

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package org.gwtbootstrap3.client.ui.form.error;

/*
 * #%L
 * GwtBootstrap3
 * %%
 * Copyright (C) 2015 GwtBootstrap3
 * %%
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 * #L%
 */

import java.util.List;

import org.gwtbootstrap3.client.ui.HelpBlock;
import org.gwtbootstrap3.client.ui.base.HasValidationState;
import org.gwtbootstrap3.client.ui.base.ValueBoxBase;
import org.gwtbootstrap3.client.ui.constants.ValidationState;

import com.google.gwt.editor.client.EditorError;
import com.google.gwt.event.logical.shared.AttachEvent;
import com.google.gwt.event.logical.shared.AttachEvent.Handler;
import com.google.gwt.user.client.ui.HasWidgets;
import com.google.gwt.user.client.ui.Widget;

/**
 * This is the default {@link ErrorHandler} implementation. The assumption is that every {@link ValueBoxBase}
 * instance will have a {@link HasValidationState} parent. If there is a {@link HelpBlock} that is a child of
 * the {@link HasValidationState} parent then error messages will be displayed in the {@link HelpBlock}.
 * 
 * Example:
 * 
 * <pre>{@code
 * <b:FormGroup> 
 *      <b:FormLabel for="username">User</b:FormLabel> 
 *      <b:TextBox b:id="username" ui:field="username" /> 
 *      <b:HelpBlock iconType="EXCLAMATION" /> 
 * </b:FormGroup>
 * }</pre>
 * 
 * @author Steven Jardine
 */
public class DefaultErrorHandler implements ErrorHandler {

    private boolean initialized = false;

    private final Widget inputWidget;

    private HelpBlock validationStateHelpBlock = null;

    private HasValidationState validationStateParent = null;

    /**
     * Default error handler.
     *
     * @param parent the parent of this error handler.
     */
    public DefaultErrorHandler(Widget widget) {
        super();
        assert widget != null;
        this.inputWidget = widget;
        this.inputWidget.addAttachHandler(new Handler() {
            @Override
            public void onAttachOrDetach(AttachEvent event) {
                init();
            }
        });
    }

    /** {@inheritDoc} */
    @Override
    public void cleanup() {
    }

    /** {@inheritDoc} */
    @Override
    public void clearErrors() {
        if (validationStateParent == null) {
            return;
        }
        validationStateParent.setValidationState(ValidationState.NONE);
        if (validationStateHelpBlock != null) {
            validationStateHelpBlock.clearError();
        }
    }

    /**
     * Find the sibling {@link HelpBlock}.
     *
     * @param widget the {@link Widget} to search.
     * @return the found {@link HelpBlock} of null if not found.
     */
    private HelpBlock findHelpBlock(Widget widget) {
        if (widget instanceof HelpBlock) {
            return (HelpBlock) widget;
        }
        // Try and find the HelpBlock in the children of the given widget.
        if (widget instanceof HasWidgets) {
            for (Widget w : (HasWidgets) widget) {
                if (w instanceof HelpBlock) {
                    return (HelpBlock) w;
                }
            }
        }
        if (!(widget instanceof HasValidationState)) {
            // Try and find the HelpBlock in the parent of widget.
            return findHelpBlock(widget.getParent());
        }
        return null;
    }

    /**
     * Initialize the instance. We find the parent {@link HasValidationState} and sibling {@link HelpBlock}
     * only 1 time on initialization.
     */
    public void init() {
        if (initialized) {
            return;
        }
        Widget parent = inputWidget.getParent();
        while (parent != null && !parent.getClass().getName().equals("com.google.gwt.user.client.ui.Widget")) {
            if (parent instanceof HasValidationState) {
                validationStateParent = (HasValidationState) parent;
                validationStateHelpBlock = findHelpBlock(inputWidget);
                break;
            }
            parent = parent.getParent();
        }
        if (inputWidget.isAttached() || validationStateParent != null) {
            initialized = true;
        }
    }

    /** {@inheritDoc} */
    @Override
    public void showErrors(List<EditorError> errors) {
        init();
        // clearErrors();
        String errorMsg = "";
        if (validationStateParent != null) {
            validationStateParent
                    .setValidationState(errors.size() <= 0 ? ValidationState.NONE : ValidationState.ERROR);
            for (int index = 0; index < errors.size(); index++) {
                errorMsg = errors.get(0).getMessage();
                if (index + 1 < errors.size()) {
                    errorMsg += "; ";
                }
            }
        }
        if (validationStateHelpBlock != null) {
            validationStateHelpBlock.setError(errorMsg);
        }
    }

}