#421 - ENH: Add support for unsetting the loaded state of a bean property (via BeanState)

src/main/java/com/avaje/ebean/BeanState.java

@@ -38,6 +38,33 @@ public interface BeanState {
    */
   void setDisableLazyLoad(boolean disableLazyLoading);
 
+  /**
+   * Set the loaded state of the property given it's name.
+   *
+   * <p>
+   *   Typically this would be used to set the loaded state of a property
+   *   to false to ensure that the specific property is excluded from a
+   *   stateless update.
+   * </p>
+   *
+   * <pre>{@code
+   *
+   *   // populate a bean via say JSON
+   *   User user = ...;
+   *
+   *   // set loaded state on the email property to false so that
+   *   // the email property is not included in a stateless update
+   *   Ebean.getBeanState(user).setPropertyLoaded("email", false);
+   *
+   *   user.update();
+   *
+   * }</pre>
+   *
+   *
+   * This will throw an IllegalArgumentException if the property is unknown.
+   */
+  void setPropertyLoaded(String propertyName, boolean loaded);
+
   /**
    * For partially populated beans returns the properties that are loaded on the
    * bean.

src/main/java/com/avaje/ebean/Model.java

@@ -1,5 +1,6 @@
 package com.avaje.ebean;
 
+import com.avaje.ebean.bean.EntityBean;
 import com.avaje.ebean.text.PathProperties;
 import com.avaje.ebean.util.ClassUtil;
 import org.jetbrains.annotations.Nullable;
@@ -193,7 +194,31 @@ public abstract class Model {
   public void markAsDirty() {
     db().markAsDirty(this);
   }
-  
+
+  /**
+   * Mark the property as unset or 'not loaded'.
+   * <p>
+   *   This would be used to specify a property that we did not wish to include in a stateless update.
+   * </p>
+   * <pre>{@code
+   *
+   *   // populate an entity bean from JSON or whatever
+   *   User user = ...;
+   *
+   *   // mark the email property as 'unset' so that it is not
+   *   // included in a 'stateless update'
+   *   user.markPropertyUnset("email");
+   *
+   *   user.update();
+   *
+   * }</pre>
+   *
+   * @param propertyName the name of the property on the bean to be marked as 'unset'
+   */
+  public void markPropertyUnset(String propertyName) {
+    ((EntityBean)this)._ebean_getIntercept().setPropertyLoaded(propertyName, false);
+  }
+
   /**
    * Insert or update this entity depending on its state.
    * 

src/main/java/com/avaje/ebean/bean/EntityBeanIntercept.java

@@ -449,7 +449,18 @@ public final class EntityBeanIntercept implements Serializable {
   public int getPropertyLength() {
     return owner._ebean_getPropertyNames().length;
   }
-  
+
+  /**
+   * Set the loaded state of the property given it's name.
+   */
+  public void setPropertyLoaded(String propertyName, boolean loaded) {
+    int position = findProperty(propertyName);
+    if (position == -1) {
+      throw new IllegalArgumentException("Property "+propertyName+" not found");
+    }
+    loadedProps[position] = loaded;
+  }
+
   /**
    * Set the property to be treated as unloaded. Used for properties initialised in default
    * constructor.

src/main/java/com/avaje/ebeaninternal/server/core/DefaultBeanState.java

@@ -1,14 +1,14 @@
 package com.avaje.ebeaninternal.server.core;
 
-import java.beans.PropertyChangeListener;
-import java.util.Map;
-import java.util.Set;
-
 import com.avaje.ebean.BeanState;
 import com.avaje.ebean.ValuePair;
 import com.avaje.ebean.bean.EntityBean;
 import com.avaje.ebean.bean.EntityBeanIntercept;
 
+import java.beans.PropertyChangeListener;
+import java.util.Map;
+import java.util.Set;
+
 /**
  * Default implementation of BeanState.
  */
@@ -23,9 +23,13 @@ public class DefaultBeanState implements BeanState {
 		this.intercept = entityBean._ebean_getIntercept();
 	}
 
-	public boolean isReference() {
-		return intercept.isReference();
-	}
+  public void setPropertyLoaded(String propertyName, boolean loaded) {
+    intercept.setPropertyLoaded(propertyName, loaded);
+  }
+
+  public boolean isReference() {
+    return intercept.isReference();
+  }
 
 	public boolean isNew() {
 		return intercept.isNew();