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This project was born out of a need to validate all POJOs (Plain Old Java Object) are behaving correctly. This project has two main aspects to it: * Make Testing as easy as possible. * Simplifying identity management (hashCode / equals) using annotation.

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/*
 * Copyright (c) 2010-2013 Osman Shoukry
 *
 *    This program is free software: you can redistribute it and/or modify
 *    it under the terms of the GNU Lesser General Public License as published by
 *    the Free Software Foundation, either version 3 of the License or any
 *    later version.
 *
 *    This program is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    GNU Lesser General Public License for more details.
 *
 *    You should have received a copy of the GNU Lesser General Public License
 *    along with this program.  If not, see .
 */

package com.openpojo.business.annotation;

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

import static java.lang.annotation.ElementType.FIELD;
import static java.lang.annotation.RetentionPolicy.RUNTIME;

/**
 * This annotation is used to indicate a field is part of the business identity.
 * Fields tagged with BusinessKey annotation will be part of the equals / hashcode.
 * Key fields are: 

 * 1. caseSensitive (default is true) 

 * 2. required (default is true) 

 * 3. composite (default is false) 

 * 

 * caseSensitive usage:

 * If a field tagged with caseSensitive=false (i.e. not case sensitive) AND the field is of type
 * Character or CharacterSequence, the field must be normalized and then hashcode/equality is performed. 

 * 

 * Example: {@link BusinessKey}(caseSensitive = false)
 * String one = "hello world" 

 * must have the same hashcode & equality as:

 * one = "HELLO WORLD" 

 * required usage:

 * If a field is tagged with required = false, then the field will only be used in equality only if its populated.
 * Two null fields tagged with required = false are equal. 

 * 

 * composite usage:

 * If a field is tagged with composite = true, then two things happen, first, required configuration is ignored,
 * and this field is treated as optional part of a group. This also means that one of the fields tagged with composite
 * MUST have a value.

 * Example:
 * If you had a POJO called Person, that had a FirstName & LastName fields, and you want to set a rule that is for this
 * POJO to be complete, one of the names MUST be populated, but its not important which one. 

 * This is typical composite key usage.
 *
 * @author oshoukry
 */
@Retention(RUNTIME)
@Target(FIELD)
public @interface BusinessKey {
    /**
     * Set to true if the field is of type Character or CharSequence to ignore case when comparing.
     */
    boolean caseSensitive() default true;

    /**
     * Set to True to indicate field required to be populated.
     */
    boolean required() default true;

    /**
     * Set to true if this key is part of a group where any one of the group needs to be not null.
     * Setting Composite to true, shadows the "required" above, since composite is OR-ing against any that are
     * populated.  With at least one of the composite group being non-null.
     */
    boolean composite() default false;
}