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Velosurf » velosurf » validation » NotNull.java
/*
 * Copyright 2003 The Apache Software Foundation.
 *
 * 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.
 */

package velosurf.validation;

import java.util.Locale;

/**
 * <p>A "not null" constraint. Syntax is:</p>
 *  <pre>
 *    &lt;<i>column</i> not-null="true"/&gt;
 *  </pre>
 *<p>Or:</p><pre>
 *   &lt;<i>column</i>&gt;
 *     &lt;not-null [message="<i>error-message</i>"]/&gt;
 *   &lt;/<i>column</i>&gt;</pre>
 * <p>To validate data coming from an HTML form, you should rather use the not-empty constraint since there cannot
 * be any null value.</p>
 * <p>Note: this constraint is not meant to replace an internal SQL "not-null" clause in the database,
 * since it cannot be made sure that complex updates will respect this constraint.</p>
 *
 *  @author <a href="mailto:claude.brisson@gmail.com">Claude Brisson</a>
 */
public class NotNull extends FieldConstraint {

    /**
     * Default constructor.
     */
    public NotNull() {
        setMessage("field {0} cannot be null");
    }

    /**
     * Validate datea against this constraint.
     * @param data the data to be validated
     * @return true if data is not null
     */
    public boolean validate(Object data) {
        return data != null;
    }

    /**
     * return a string representation for this constraint.
     * @return string
     */
    public String toString() {
        return "not-null";
    }
}
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