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POForeignCollection initialization in domain class
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  1. POForeignCollection initialization in domain class
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    copied!<p>I have a domain objects with many-to-many relationship. <code>Menu</code> can have many <code>Categories</code> and <code>Category</code> can be in many <code>Menus</code>. <code>Menu</code> is responsible for <code>Categories</code>.</p> <p>I have made quite layered design for my application and domain classes are strictly separated from <code>DAO</code>-s (I have a special synchronization classes for accessing Factory and Repository classes and keeping relationships in sync) and Application layer (I use services there, for example <code>AddMenuService</code> where all the logic resides). </p> <p>For example I create a <code>Menu</code> and <code>Category</code> objects. Add this category to menu via special appender class. Then I synchronize objects (validate, check if object exists in database or create a new object, calling other Synchro classes if needed, comparing objects from difference and saving or updating them). Categories can be added only through MenuSyncro.</p> <pre><code>Menu m1 = new Menu("Menu for vegetarians"); Category cat1 = new Category("Drinks"); m1.getAppender().addCategory(cat1); MenuSyncro ms = new MenuSyncro(); ms.synchronize(menu1); </code></pre> <p>I know that I can use <code>Dao.getEmptyForeignCollection(String fieldName);</code>, but is there any way to initialize <code>ForeginCollection&lt;MenuCategory&gt; categories;</code> in <code>Menu</code> class and <code>ForeignCollection&lt;MenuCategory&gt; menus;</code> in <code>Category</code> class without to access DAO objects first, because i keep getting <code>NullReference</code> exceptions because those collections are not initalized?</p> <h2>Classes</h2> <p><strong>Menu.class</strong></p> <pre><code>@DatabaseTable(tableName = "MENUS") public class Menu { private final static String ID_FIELD_NAME = "ID"; private final static String NAME_FIELD_NAME = "NAME"; @DatabaseField(generatedId = true, columnName = ID_FIELD_NAME) private int id; @DatabaseField(columnName = NAME_FIELD_NAME, canBeNull = false, unique = true, useGetSet = true) private String name; @ForeignCollectionField(eager = false) private ForeignCollection&lt;MenuCategory&gt; categories; @ForeignCollectionField(eager = false) private ForeignCollection&lt;LocationMenu&gt; locations; private MenuAppender appender; public Menu() { // for ORMLite } public Menu(String name) { this.name = name; } public int getId() { return id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public ArrayList&lt;Category&gt; getCategories() { ArrayList&lt;Category&gt; categoriesList = new ArrayList&lt;Category&gt;(); if (categories != null) for (MenuCategory menuCategory : categories) categoriesList.add(menuCategory.getCategory()); return categoriesList; } public ForeignCollection&lt;LocationMenu&gt; getLocations() { return locations; } public MenuAppender getAppender() { if (appender== null) appender= new MenuAppender(this); return appender; } } </code></pre> <p><strong>Category.class</strong></p> <pre><code>@DatabaseTable(tableName = "CATEGORIES") public class Category { private final static String ID_FIELD_NAME = "ID"; private final static String NAME_FIELD_NAME = "NAME"; @DatabaseField(generatedId = true, columnName = ID_FIELD_NAME) private int id; @DatabaseField(columnName = NAME_FIELD_NAME, canBeNull = false, unique = true, useGetSet = true) private String name; @ForeignCollectionField(eager = false) private ForeignCollection&lt;MenuCategory&gt; menus; public Category() { // for ORMLite } public Category(String name) { this.name = name; } public int getId() { return id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public ArrayList&lt;Menu&gt; getMenus() { ArrayList&lt;Menu&gt; menusList = new ArrayList&lt;Menu&gt;(); if (menus != null) for (MenuCategory menuCategory : menus) menusList.add(menuCategory.getMenu()); return menusList; } </code></pre> <p>}</p> <p><strong>MenuCategory.class</strong></p> <pre><code> @DatabaseTable(tableName = "MENUS_CATEGORIES") public class MenuCategory { private final static String ID_FIELD_NAME = "ID"; private final static String MENUS_ID_FIELD_NAME = "MENUS_ID"; private final static String CATEGORIES_ID_FIELD_NAME = "CATEGORIES_ID"; @SuppressWarnings("unused") @DatabaseField(generatedId = true, columnName = ID_FIELD_NAME) private int id; @DatabaseField(foreign = true, columnName = MENUS_ID_FIELD_NAME, canBeNull = false, foreignAutoCreate = true, foreignAutoRefresh = true) private Menu menu; @DatabaseField(foreign = true, columnName = CATEGORIES_ID_FIELD_NAME, canBeNull = false, foreignAutoCreate = true, foreignAutoRefresh = true) private Category category; public MenuCategory() { // for ORMLite } public MenuCategory(Menu menu, Category category) { this.menu = menu; this.category = category; } public Menu getMenu() { return menu; } public void setMenu(Menu menu) { this.menu = menu; } public Category getCategory() { return category; } public void setCategory(Category category) { this.category = category; } } </code></pre> <p>Thanks in advance, evilone</p>
 

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