net.java.ao.OneToOne Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of activeobjects Show documentation

This is the full Active Objects library, if you don't know which one to use, you probably want this one.

There is a newer version: 6.1.1

/*
 * Copyright 2007 Daniel Spiewak
 * 
 * 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 net.java.ao;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

/**
 * Marks a method as relevant only to a one-to-one relation.  This
 * informs ActiveObjects that the return value for the method in question
 * should be determined from a one-to-one relation onto the type in the
 * return value.  For example:
 *
 * public interface User {
 *     // ...
 *
 *     @OneToOne
 *     public Password getPassword();
 * }
 *
 * Thus the return value of the getPassword() method
 * would be determined by a query something like the following:
 *
 * SELECT id FROM passwords WHERE userID = ?
 *
 * If the {@link #where()} clause is specified, it will be used
 * in addition to the base, necessary criterion to determine the
 * returned entities.  Thus, the one-to-one relation could be referenced
 * in the following way:
 *
 * public interface User {
 *     // ...
 *
 *     @OneToOne(where="deleted = FALSE")
 *     public Password getPassword();
 * }
 *
 * This would lead to a query like the following:
 *
 * SELECT id FROM passwords WHERE userID = ? AND (deleted = FALSE)
 *
 * @author Daniel Spiewak
 */
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
public @interface OneToOne {

    /**
     * The name of the corresponding getter method in the remote entity.
     *
     * If this is not specified, a warning will be logged at migration time, and ActiveObjects may behave in
     * unexpected ways. Future versions of ActiveObjects may require that this property be specified.
     *
     * @see AO-325
     */
    String reverse() default "";

    /**
     * A String clause allowing developer-specified additional
     * conditions to be imposed on the relationship.  The String
     * must be a proper SQL WHERE clause:
     *
     * "deleted = FALSE"
     *
     * One must be extremely careful with this sort of thing though
     * because sometimes (as is the case with the above sample), the
     * unparameterized code may not execute as expected against every
     * database (due to differences in typing and value handling).  Thus,
     * in all but non-trivial cases, defined implementations should be used.
     */
    String where() default "";
}