#494 - ENH: Support findPagingList() ... that uses firstRow & maxRows (rather than pageIndex, pageSize)

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

@@ -1020,7 +1020,7 @@ public interface EbeanServer {
   SqlFutureList findFutureList(SqlQuery query, Transaction transaction);
 
   /**
-   * Return a PagedList for this query.
+   * Return a PagedList for this query using pageIndex and pageSize.
    * <p>
    * The benefit of using this over just using the normal {@link Query#setFirstRow(int)} and
    * {@link Query#setMaxRows(int)} is that it additionally wraps an optional call to
@@ -1042,6 +1042,38 @@ public interface EbeanServer {
    */
   <T> PagedList<T> findPagedList(Query<T> query, Transaction transaction, int pageIndex, int pageSize);
 
+  /**
+   * Return a PagedList for this query using firstRow and maxRows.
+   * <p>
+   * The benefit of using this over findList() is that it provides functionality to get the
+   * total row count etc.
+   * </p>
+   * <p>
+   * If maxRows is not set on the query prior to calling findPagedList() then a
+   * PersistenceException is thrown.
+   * </p>
+   *
+   * <pre>{@code
+   *
+   *  PagedList<Order> pagedList = Ebean.find(Order.class)
+   *       .setFirstRow(50)
+   *       .setMaxRows(20)
+   *       .findPagedList();
+   *
+   *       // fetch the total row count in the background
+   *       pagedList.loadRowCount();
+   *
+   *       List<Order> orders = pagedList.getList();
+   *       int totalRowCount = pagedList.getTotalRowCount();
+   *
+   * }</pre>
+   *
+   * @return The PagedList
+   *
+   * @see Query#findPagedList()
+   */
+  <T> PagedList<T> findPagedList(Query<T> query, Transaction transaction);
+
   /**
    * Execute the query returning a set of entity beans.
    * <p>

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

@@ -245,7 +245,7 @@ public interface ExpressionList<T> extends Serializable {
   FutureList<T> findFutureList();
 
   /**
-   * Return a PagedList for this query.
+   * Return a PagedList for this query using pageIndex and pageSize.
    * <p>
    * The benefit of using this over just using the normal {@link Query#setFirstRow(int)} and
    * {@link Query#setMaxRows(int)} is that it additionally wraps an optional call to
@@ -265,6 +265,38 @@ public interface ExpressionList<T> extends Serializable {
    */
   PagedList<T> findPagedList(int pageIndex, int pageSize);
 
+  /**
+   * Return a PagedList for this query using firstRow and maxRows.
+   * <p>
+   * The benefit of using this over findList() is that it provides functionality to get the
+   * total row count etc.
+   * </p>
+   * <p>
+   * If maxRows is not set on the query prior to calling findPagedList() then a
+   * PersistenceException is thrown.
+   * </p>
+   *
+   * <pre>{@code
+   *
+   *  PagedList<Order> pagedList = Ebean.find(Order.class)
+   *       .setFirstRow(50)
+   *       .setMaxRows(20)
+   *       .findPagedList();
+   *
+   *       // fetch the total row count in the background
+   *       pagedList.loadRowCount();
+   *
+   *       List<Order> orders = pagedList.getList();
+   *       int totalRowCount = pagedList.getTotalRowCount();
+   *
+   * }</pre>
+   *
+   * @return The PagedList
+   *
+   * @see Query#findPagedList()
+   */
+  PagedList<T> findPagedList();
+
   /**
    * Return versions of a @History entity bean.
    * <p>

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

@@ -17,6 +17,33 @@ import java.util.concurrent.Future;
  * limit the result set.
  * </p>
  *
+ *
+ * <h4>Example: typical use including total row count</h4>
+ * <pre>{@code
+ *
+ *     // We want to find the first 50 new orders
+ *     //  ... so we don't really need setFirstRow(0)
+ *
+ *     PagedList<Order> pagedList
+ *       = ebeanServer.find(Order.class)
+ *       .where().eq("status", Order.Status.NEW)
+ *       .order().asc("id")
+ *       .setFirstRow(0)
+ *       .setMaxRows(50)
+ *       .findPagedList();
+ *
+ *     // Optional: initiate the loading of the total
+ *     // row count in a background thread
+ *     pagedList.loadRowCount();
+ *
+ *     // fetch and return the list in the foreground thread
+ *     List<Order> orders = pagedList.getList();
+ *
+ *     // get the total row count (from the future)
+ *     int totalRowCount = pagedList.getTotalRowCount();
+ *
+ * }</pre>
+ *
  * <h4>Example: typical use including total row count</h4>
  * <pre>{@code
  *
@@ -156,11 +183,15 @@ public interface PagedList<T> {
 
   /**
    * Return the index position of this page. Zero based.
+   * <p>
+   * Note that if firstRows/maxRows is used rather than pageIndex/pageSize then
+   * this always returns 0.
+   * </p>
    */
   int getPageIndex();
 
   /**
-   * Return the page size used for this query.
+   * Return the page size used for this query. This is the same value as maxRows used by the query.
    */
   int getPageSize();
 

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

@@ -822,7 +822,7 @@ public interface Query<T> extends Serializable {
   FutureList<T> findFutureList();
 
   /**
-   * Return a PagedList for this query.
+   * Return a PagedList for this query using pageIndex and pageSize.
    * <p>
    * The benefit of using this over just using the normal {@link Query#setFirstRow(int)} and
    * {@link Query#setMaxRows(int)} is that it additionally wraps an optional call to
@@ -867,6 +867,36 @@ public interface Query<T> extends Serializable {
    */
   PagedList<T> findPagedList(int pageIndex, int pageSize);
 
+  /**
+   * Return a PagedList for this query using firstRow and maxRows.
+   * <p>
+   * The benefit of using this over findList() is that it provides functionality to get the
+   * total row count etc.
+   * </p>
+   * <p>
+   * If maxRows is not set on the query prior to calling findPagedList() then a
+   * PersistenceException is thrown.
+   * </p>
+   *
+   * <pre>{@code
+   *
+   *  PagedList<Order> pagedList = Ebean.find(Order.class)
+   *       .setFirstRow(50)
+   *       .setMaxRows(20)
+   *       .findPagedList();
+   *
+   *       // fetch the total row count in the background
+   *       pagedList.loadRowCount();
+   *
+   *       List<Order> orders = pagedList.getList();
+   *       int totalRowCount = pagedList.getTotalRowCount();
+   *
+   * }</pre>
+   *
+   * @return The PagedList
+   */
+  PagedList<T> findPagedList();
+
   /**
    * Set a named bind parameter. Named parameters have a colon to prefix the name.
    * 

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

@@ -1384,6 +1384,18 @@ public final class DefaultServer implements SpiServer, SpiEbeanServer {
     return new LimitOffsetPagedList<T>(this, (SpiQuery<T>)query, pageIndex, pageSize);
   }
 
+  @Override
+  public <T> PagedList<T> findPagedList(Query<T> query, Transaction transaction) {
+
+    SpiQuery<T> spiQuery = (SpiQuery<T>)query;
+    int maxRows = spiQuery.getMaxRows();
+    if (maxRows == 0) {
+      throw new PersistenceException("maxRows must be specified for findPagedList() query");
+    }
+
+    return new LimitOffsetPagedList<T>(this, spiQuery);
+  }
+
   public <T> void findEach(Query<T> query, QueryEachConsumer<T> consumer, Transaction t) {
 
     SpiOrmQueryRequest<T> request = createQueryRequest(Type.ITERATE, query, t);

src/main/java/com/avaje/ebeaninternal/server/expression/JunctionExpression.java

@@ -314,6 +314,11 @@ abstract class JunctionExpression<T> implements Junction<T>, SpiExpression, Expr
     return exprList.findPagedList(pageIndex, pageSize);
   }
 
+  @Override
+  public PagedList<T> findPagedList() {
+    return exprList.findPagedList();
+  }
+
   @Override
   public int findRowCount() {
     return exprList.findRowCount();

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

@@ -21,7 +21,9 @@ public class LimitOffsetPagedList<T> implements PagedList<T> {
 
   private final SpiQuery<T> query;
 
-  private final int pageSize;
+  private final int firstRow;
+
+  private final int maxRows;
 
   private final int pageIndex;
 
@@ -33,11 +35,29 @@ public class LimitOffsetPagedList<T> implements PagedList<T> {
 
   private List<T> list;
 
+  /**
+   * Construct with pageIndex/pageSize.
+   */
   public LimitOffsetPagedList(EbeanServer server, SpiQuery<T> query, int pageIndex, int pageSize) {
     this.server = server;
     this.query = query;
-    this.pageSize = pageSize;
+    this.maxRows = pageSize;
+    this.firstRow = pageIndex * pageSize;
     this.pageIndex = pageIndex;
+
+    query.setFirstRow(firstRow);
+    query.setMaxRows(pageSize);
+  }
+
+  /**
+   * Construct with firstRow/maxRows.
+   */
+  public LimitOffsetPagedList(EbeanServer server, SpiQuery<T> query) {
+    this.server = server;
+    this.query = query;
+    this.maxRows = query.getMaxRows();
+    this.firstRow = query.getFirstRow();
+    this.pageIndex = 0;
   }
 
   public void loadRowCount() {
@@ -56,8 +76,6 @@ public class LimitOffsetPagedList<T> implements PagedList<T> {
   public List<T> getList() {
     synchronized (monitor) {
       if (list == null) {
-        query.setFirstRow(pageIndex * pageSize);
-        query.setMaxRows(pageSize);
         list = server.findList(query, null);
       }
       return list;
@@ -70,7 +88,7 @@ public class LimitOffsetPagedList<T> implements PagedList<T> {
     if (rowCount == 0) {
       return 0;
     } else {
-      return ((rowCount - 1) / pageSize) + 1;
+      return ((rowCount - 1) / maxRows) + 1;
     }
   }
 
@@ -94,11 +112,11 @@ public class LimitOffsetPagedList<T> implements PagedList<T> {
   }
 
   public boolean hasNext() {
-    return pageIndex < (getTotalPageCount() - 1);
+    return (firstRow + maxRows) < getTotalRowCount();
   }
 
   public boolean hasPrev() {
-    return pageIndex > 0;
+    return firstRow > 0;
   }
 
   public int getPageIndex() {
@@ -106,13 +124,13 @@ public class LimitOffsetPagedList<T> implements PagedList<T> {
   }
 
   public int getPageSize() {
-    return pageSize;
+    return maxRows;
   }
 
   public String getDisplayXtoYofZ(String to, String of) {
 
-    int first = pageIndex * pageSize + 1;
-    int last = first + getList().size() - 1;
+    int first = firstRow + 1;
+    int last = firstRow + getList().size();
     int total = getTotalRowCount();
 
     return first + to + last + of + total;

src/main/java/com/avaje/ebeaninternal/server/querydefn/DefaultOrmQuery.java

@@ -1094,6 +1094,11 @@ public class DefaultOrmQuery<T> implements SpiQuery<T> {
     return server.findPagedList(this, null, pageIndex, pageSize);
   }
 
+  @Override
+  public PagedList<T> findPagedList() {
+    return server.findPagedList(this, null);
+  }
+
   /**
    * Set an ordered bind parameter according to its position. Note that the position starts at 1 to
    * be consistent with JDBC PreparedStatement. You need to set a parameter value for each ? you

src/main/java/com/avaje/ebeaninternal/util/DefaultExpressionList.java

@@ -201,6 +201,11 @@ public class DefaultExpressionList<T> implements SpiExpressionList<T> {
     return query.findPagedList(pageIndex, pageSize);
   }
 
+  @Override
+  public PagedList<T> findPagedList() {
+    return query.findPagedList();
+  }
+
   @Override
   public int findRowCount() {
     return query.findRowCount();