#125 - ENH: Add support for query returning a List of single Attribute type

src/main/java/com/avaje/ebeaninternal/api/SpiQuery.java

@@ -78,6 +78,11 @@ public interface SpiQuery<T> extends Query<T> {
      */
     ID_LIST,
 
+    /**
+     * Find single attribute.
+     */
+    ATTRIBUTE,
+
     /**
      * Find rowCount.
      */
@@ -341,6 +346,24 @@ public interface SpiQuery<T> extends Query<T> {
    */
   void setSelectId();
 
+  /**
+   * Mark the query as selecting a single attribute.
+   */
+  void setSingleAttribute();
+
+  /**
+   * Return true if this is singleAttribute query.
+   */
+  boolean isSingleAttribute();
+
+  /**
+   * Return true if the query should include the Id property.
+   * <p>
+   * distinct and single attribute queries exclude the Id property.
+   * </p>
+   */
+  boolean isWithId();
+
   /**
    * Set a filter to a join path.
    */