#410 - Require findPagedList() query to specify an order by clause - throw exception if no order by supplied

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

@@ -28,7 +28,7 @@ public final class OrderBy<T> implements Serializable {
    * Create an empty OrderBy with no associated query.
    */
   public OrderBy() {
-    this.list = new ArrayList<Property>(2);
+    this.list = new ArrayList<Property>(3);
   }
   
   private OrderBy(List<Property> list) {
@@ -52,7 +52,7 @@ public final class OrderBy<T> implements Serializable {
    */
   public OrderBy(Query<T> query, String orderByClause) {
     this.query = query;
-    this.list = new ArrayList<Property>(2);
+    this.list = new ArrayList<Property>(3);
     parse(orderByClause);
   }
 
@@ -83,6 +83,19 @@ public final class OrderBy<T> implements Serializable {
     return query;
   }
 
+  /**
+   * Return true if the property is known to be contained in the order by clause.
+   */
+  public boolean containsProperty(String propertyName) {
+
+    for (int i = 0; i < list.size(); i++) {
+      if (propertyName.equals(list.get(i).getProperty())) {
+        return true;
+      }
+    }
+    return false;
+  }
+
   /**
    * Return a copy of this OrderBy with the path trimmed.
    */

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

@@ -1363,14 +1363,7 @@ public final class DefaultServer implements SpiServer, SpiEbeanServer {
   @Override
   public <T> PagedList<T> findPagedList(Query<T> query, Transaction transaction, int pageIndex, int pageSize) {
 
-    SpiQuery spiQuery = (SpiQuery<T>)query;
-    OrderBy orderBy = spiQuery.getOrderBy();
-    if (orderBy == null || orderBy.isEmpty()) {
-      // add a default order by for paging queries
-      BeanDescriptor<T> desc = beanDescriptorManager.getBeanDescriptor(spiQuery.getBeanType());
-      query.orderBy(desc.getDefaultOrderBy());
-    }
-    return new LimitOffsetPagedList<T>(this, spiQuery, pageIndex, pageSize);
+    return new LimitOffsetPagedList<T>(this, (SpiQuery<T>)query, pageIndex, pageSize);
   }
 
   public <T> void findEach(Query<T> query, QueryEachConsumer<T> consumer, Transaction t) {

src/main/java/com/avaje/ebeaninternal/server/deploy/BeanDescriptor.java

@@ -1,5 +1,6 @@
 package com.avaje.ebeaninternal.server.deploy;
 
+import com.avaje.ebean.OrderBy;
 import com.avaje.ebean.SqlUpdate;
 import com.avaje.ebean.Transaction;
 import com.avaje.ebean.ValuePair;
@@ -2098,6 +2099,26 @@ public class BeanDescriptor<T> implements MetaBeanInfo, SpiBeanType<T> {
     }
   }
 
+  /**
+   * Appends the Id property to the OrderBy clause if it is not believed
+   * to be already contained in the order by.
+   * <p>
+   * This is primarily used for paging queries to ensure that an order by clause is provided and that the order by
+   * provides unique ordering of the rows (so that the paging is predicable).
+   * </p>
+   */
+  public void appendOrderById(SpiQuery<T> query) {
+
+    if (idProperty != null) {
+      OrderBy<T> orderBy = query.getOrderBy();
+      if (orderBy == null || orderBy.isEmpty()) {
+        query.order().asc(idProperty.getName());
+      } else if (!orderBy.containsProperty(idProperty.getName())){
+        query.order().asc(idProperty.getName());
+      }
+    }
+  }
+
   /**
    * All the BeanPropertyAssocOne that are not embedded. These are effectively
    * joined beans. For ManyToOne and OneToOne associations.

src/main/java/com/avaje/ebeaninternal/server/query/CQueryEngine.java

@@ -277,6 +277,14 @@ public class CQueryEngine {
    */
   public <T> BeanCollection<T> findMany(OrmQueryRequest<T> request) {
 
+
+    SpiQuery<T> query = request.getQuery();
+    if (query.getMaxRows() > 1 || query.getFirstRow() > 0) {
+      // deemed to be a be a paging query - check that the order by contains
+      // the id property to ensure unique row ordering for predicable paging
+      request.getBeanDescriptor().appendOrderById(query);
+    }
+
     CQuery<T> cquery = queryBuilder.buildQuery(request);
     request.setCancelableQuery(cquery);
 
@@ -293,7 +301,7 @@ public class CQueryEngine {
 
       BeanCollection<T> beanCollection = cquery.readCollection();
 
-      BeanCollectionTouched collectionTouched = request.getQuery().getBeanCollectionTouched();
+      BeanCollectionTouched collectionTouched = query.getBeanCollectionTouched();
       if (collectionTouched != null) {
         // register a listener that wants to be notified when the
         // bean collection is first used
@@ -319,7 +327,7 @@ public class CQueryEngine {
       if (cquery != null) {
         cquery.close();
       }
-      if (request.getQuery().isFutureFetch()) {
+      if (query.isFutureFetch()) {
         // end the transaction for futureFindIds
         // as it had it's own transaction
         logger.debug("Future fetch completed!");