Add SHARED_GLOBAL_IDS entity flag, update ModelProperty docs

Author: greenrobot

objectbox-java/src/main/java/io/objectbox/model/EntityFlags.java

@@ -32,8 +32,18 @@ private EntityFlags() { }
    * It's possible to have local-only (non-synced) types and synced types in the same store (schema/data model).
    */
   public static final int SYNC_ENABLED = 2;
+  /**
+   * Makes object IDs for a synced types (SYNC_ENABLED is set) global.
+   * By default (not using this flag), the 64 bit object IDs have a local scope and are not unique globally.
+   * This flag tells ObjectBox to treat object IDs globally and thus no ID mapping (local <-> global) is performed.
+   * Often this is used with assignable IDs (ID_SELF_ASSIGNABLE property flag is set) and some special ID scheme.
+   * Note: typically you won't do this with automatically assigned IDs, set by the local ObjectBox store.
+   *       Two devices would likely overwrite each other's object during sync as object IDs are prone to collide.
+   *       It might be OK if you can somehow ensure that only a single device will create new IDs.
+   */
+  public static final int SHARED_GLOBAL_IDS = 4;
 
-  public static final String[] names = { "USE_NO_ARG_CONSTRUCTOR", "SYNC_ENABLED", };
+  public static final String[] names = { "USE_NO_ARG_CONSTRUCTOR", "SYNC_ENABLED", "", "SHARED_GLOBAL_IDS", };
 
   public static String name(int e) { return names[e - USE_NO_ARG_CONSTRUCTOR]; }
 }

objectbox-java/src/main/java/io/objectbox/model/ModelProperty.java

@@ -44,13 +44,20 @@ public final class ModelProperty extends Table {
   public io.objectbox.model.IdUid indexId() { return indexId(new io.objectbox.model.IdUid()); }
   public io.objectbox.model.IdUid indexId(io.objectbox.model.IdUid obj) { int o = __offset(12); return o != 0 ? obj.__assign(o + bb_pos, bb) : null; }
   /**
-   * For relations only: name of the target entity
+   * For relations only: name of the target entity (will be replaced by "target entity ID" at the schema level)
    */
   public String targetEntity() { int o = __offset(14); return o != 0 ? __string(o + bb_pos) : null; }
   public ByteBuffer targetEntityAsByteBuffer() { return __vector_as_bytebuffer(14, 1); }
   public ByteBuffer targetEntityInByteBuffer(ByteBuffer _bb) { return __vector_in_bytebuffer(_bb, 14, 1); }
   /**
-   * E.g. for virtual to-one target ID properties, this references the ToOne object
+   * This will probably move out of the core model into something binding specific.
+   * A virtual property's "target name" typically references an existing field in the entity at the language level
+   * of the binding. In contrast to this, the virtual property (via model "name") does not exist in the entity at
+   * the language level (thus virtual), but in ObjectBox's core DB.
+   * Example: consider a Java entity which has a ToOne (a Java specific relation wrapper) member called "parent".
+   * ObjectBox core is unaware of that ToOne, but works with the "parentId" relation property,
+   * which in turn does not exist in the Java entity.
+   * The mapping between "parentId" and "parent" is done by our JNI binding.
    */
   public String virtualTarget() { int o = __offset(16); return o != 0 ? __string(o + bb_pos) : null; }
   public ByteBuffer virtualTargetAsByteBuffer() { return __vector_as_bytebuffer(16, 1); }