Rename DB_result _data_seek() to data_seek() and make it publicly available

(as requested in #2050)

11 files changed, 57 insertions, 25 deletions

diff --git a/system/database/DB_result.php b/system/database/DB_result.php
index 9d19075ba..e1ef341a5 100644
--- a/system/database/DB_result.php
+++ b/system/database/DB_result.php
@@ -203,7 +203,7 @@ class CI_DB_result {
 			return $this->custom_result_object[$class_name];
 		}
 
-		$this->_data_seek(0);
+		$this->data_seek(0);
 		$this->custom_result_object[$class_name] = array();
 
 		while ($row = $this->_fetch_object($class_name))
@@ -246,7 +246,7 @@ class CI_DB_result {
 			return $this->result_object;
 		}
 
-		$this->_data_seek(0);
+		$this->data_seek(0);
 		while ($row = $this->_fetch_object())
 		{
 			$this->result_object[] = $row;
@@ -287,7 +287,7 @@ class CI_DB_result {
 			return $this->result_array;
 		}
 
-		$this->_data_seek(0);
+		$this->data_seek(0);
 		while ($row = $this->_fetch_assoc())
 		{
 			$this->result_array[] = $row;
@@ -617,7 +617,7 @@ class CI_DB_result {
 	 * @param	int	$n
 	 * @return	bool
 	 */
-	protected function _data_seek($n = 0)
+	public function data_seek($n = 0)
 	{
 		return FALSE;
 	}
diff --git a/system/database/drivers/cubrid/cubrid_result.php b/system/database/drivers/cubrid/cubrid_result.php
index 130eea212..793b35b74 100644
--- a/system/database/drivers/cubrid/cubrid_result.php
+++ b/system/database/drivers/cubrid/cubrid_result.php
@@ -130,7 +130,7 @@ class CI_DB_cubrid_result extends CI_DB_result {
 	 * @param	int	$n
 	 * @return	bool
 	 */
-	protected function _data_seek($n = 0)
+	public function data_seek($n = 0)
 	{
 		return cubrid_data_seek($this->result_id, $n);
 	}
diff --git a/system/database/drivers/mssql/mssql_result.php b/system/database/drivers/mssql/mssql_result.php
index a8f850d72..ca222aed4 100644
--- a/system/database/drivers/mssql/mssql_result.php
+++ b/system/database/drivers/mssql/mssql_result.php
@@ -135,7 +135,7 @@ class CI_DB_mssql_result extends CI_DB_result {
 	 * @param	int	$n
 	 * @return	bool
 	 */
-	protected function _data_seek($n = 0)
+	public function data_seek($n = 0)
 	{
 		return mssql_data_seek($this->result_id, $n);
 	}
diff --git a/system/database/drivers/mysql/mysql_result.php b/system/database/drivers/mysql/mysql_result.php
index a6dcde4e7..293980e97 100644
--- a/system/database/drivers/mysql/mysql_result.php
+++ b/system/database/drivers/mysql/mysql_result.php
@@ -149,7 +149,7 @@ class CI_DB_mysql_result extends CI_DB_result {
 	 * @param	int	$n
 	 * @return	bool
 	 */
-	protected function _data_seek($n = 0)
+	public function data_seek($n = 0)
 	{
 		return $this->num_rows
 			? @mysql_data_seek($this->result_id, $n)
diff --git a/system/database/drivers/mysqli/mysqli_result.php b/system/database/drivers/mysqli/mysqli_result.php
index d55188e68..ac0f1a8d1 100644
--- a/system/database/drivers/mysqli/mysqli_result.php
+++ b/system/database/drivers/mysqli/mysqli_result.php
@@ -136,7 +136,7 @@ class CI_DB_mysqli_result extends CI_DB_result {
 	 * @param	int	$n
 	 * @return	bool
 	 */
-	protected function _data_seek($n = 0)
+	public function data_seek($n = 0)
 	{
 		return $this->result_id->data_seek($n);
 	}
diff --git a/system/database/drivers/oci8/oci8_result.php b/system/database/drivers/oci8/oci8_result.php
index 7d5bf5172..661ea4944 100644
--- a/system/database/drivers/oci8/oci8_result.php
+++ b/system/database/drivers/oci8/oci8_result.php
@@ -240,8 +240,13 @@ class CI_DB_oci8_result extends CI_DB_result {
 	 * @param	int	$n	(ignored)
 	 * @return	bool
 	 */
-	protected function _data_seek($n = 0)
+	public function data_seek($n = 0)
 	{
+		if ($n > 0)
+		{
+			return FALSE;
+		}
+
 		/* The PHP manual says that if OCI_NO_AUTO_COMMIT mode
 		 * is used, and oci_rollback() and/or oci_commit() are
 		 * not subsequently called - this will cause an unnecessary
diff --git a/system/database/drivers/postgre/postgre_result.php b/system/database/drivers/postgre/postgre_result.php
index 3a4e57c42..fdaeaef70 100644
--- a/system/database/drivers/postgre/postgre_result.php
+++ b/system/database/drivers/postgre/postgre_result.php
@@ -133,7 +133,7 @@ class CI_DB_postgre_result extends CI_DB_result {
 	 * @param	int	$n
 	 * @return	bool
 	 */
-	protected function _data_seek($n = 0)
+	public function data_seek($n = 0)
 	{
 		return pg_result_seek($this->result_id, $n);
 	}
diff --git a/system/database/drivers/sqlite/sqlite_result.php b/system/database/drivers/sqlite/sqlite_result.php
index 24f02a8b4..889757dea 100644
--- a/system/database/drivers/sqlite/sqlite_result.php
+++ b/system/database/drivers/sqlite/sqlite_result.php
@@ -117,7 +117,7 @@ class CI_DB_sqlite_result extends CI_DB_result {
 	 * @param	int	$n
 	 * @return	bool
 	 */
-	protected function _data_seek($n = 0)
+	public function data_seek($n = 0)
 	{
 		return sqlite_seek($this->result_id, $n);
 	}
diff --git a/system/database/drivers/sqlite3/sqlite3_result.php b/system/database/drivers/sqlite3/sqlite3_result.php
index 44fef8909..69c42002c 100644
--- a/system/database/drivers/sqlite3/sqlite3_result.php
+++ b/system/database/drivers/sqlite3/sqlite3_result.php
@@ -175,10 +175,10 @@ class CI_DB_sqlite3_result extends CI_DB_result {
 	 * @param	int	$n	(ignored)
 	 * @return	array
 	 */
-	protected function _data_seek($n = 0)
+	public function data_seek($n = 0)
 	{
 		// Only resetting to the start of the result set is supported
-		return $this->result_id->reset();
+		return ($n > 0) ? FALSE : $this->result_id->reset();
 	}
 
 }
diff --git a/user_guide_src/source/changelog.rst b/user_guide_src/source/changelog.rst
index 9b0ea53c4..c2606f3f3 100644
--- a/user_guide_src/source/changelog.rst
+++ b/user_guide_src/source/changelog.rst
@@ -106,7 +106,6 @@ Release Date: Not Released
    -  Added **schema** configuration setting (defaults to *public*) for drivers that might need it (currently used by PostgreSQL and ODBC).
    -  Added subdrivers support (currently only used by PDO).
    -  Added an optional database name parameter to ``db_select()``.
-   -  Added a constructor to the ``DB_result`` class and moved all driver-specific properties and logic out of the base ``DB_driver`` class to allow better abstraction.
    -  Removed ``protect_identifiers()`` and renamed internal method ``_protect_identifiers()`` to it instead - it was just an alias.
    -  Renamed internal method ``_escape_identifiers()`` to ``escape_identifiers()``.
    -  Updated ``escape_identifiers()`` to accept an array of fields as well as strings.
@@ -114,8 +113,7 @@ Release Date: Not Released
    -  ``db_set_charset()`` now only requires one parameter (collation was only needed due to legacy support for MySQL versions prior to 5.1).
    -  Replaced the ``_error_message()`` and ``_error_number()`` methods with ``error()``, which returns an array containing the last database error code and message.
    -  Improved ``version()`` implementation so that drivers that have a native function to get the version number don't have to be defined in the core ``DB_driver`` class.
-   -  Added ``unbuffered_row()`` method for getting a row without prefetching whole result (consume less memory).
-   -  Added capability for packages to hold *database.php* config files.
+   -  Added capability for packages to hold *config/database.php* config files.
    -  Added MySQL client compression support.
    -  Added encrypted connections support (for *mysql*, *sqlsrv* and PDO with *sqlsrv*).
    -  Removed :doc:`Loader Class <libraries/loader>` from Database error tracing to better find the likely culprit.
@@ -133,6 +131,10 @@ Release Date: Not Released
 	 - Changed ``limit()`` to ignore NULL values instead of always casting to integer.
 	 - Changed ``offset()`` to ignore empty values instead of always casting to integer.
 	 - Methods ``insert_batch()`` and ``update_batch()`` now return an integer representing the number of rows affected by them.
+   -  :doc:`Database Results <database/results>` changes include:
+	 - Added a constructor to the ``DB_result`` class and moved all driver-specific properties and logic out of the base ``DB_driver`` class to allow better abstraction.
+	 - Added method ``unbuffered_row()`` for fetching a row without prefetching the whole result (consume less memory).
+	 - Renamed former method ``_data_seek()`` to ``data_seek()`` and made it public.
    -  Improved support for the MySQLi driver, including:
 	 - OOP style of the PHP extension is now used, instead of the procedural aliases.
 	 - Server version checking is now done via ``mysqli::$server_info`` instead of running an SQL query.
diff --git a/user_guide_src/source/database/results.rst b/user_guide_src/source/database/results.rst
index d032f734e..e0a87a851 100644
--- a/user_guide_src/source/database/results.rst
+++ b/user_guide_src/source/database/results.rst
@@ -99,7 +99,7 @@ to instantiate the row with::
 	echo $row->reverse_name(); // or methods defined on the 'User' class
 
 row_array()
-============
+===========
 
 Identical to the above row() function, except it returns an array.
 Example::
@@ -138,12 +138,12 @@ parameter:
 
 .. note:: all the functions above will load the whole result into memory (prefetching) use unbuffered_row() for processing large result sets.
 
-unbuffered_row($type)
-=====================
+unbuffered_row()
+================
 
-This function returns a single result row without prefetching the whole result in memory as row() does.
-If your query has more than one row, it returns the current row and moves the internal data pointer ahead. 
-The result is returned as $type could be 'object' (default) or 'array' that will return an associative array.
+This method returns a single result row without prefetching the whole
+result in memory as ``row()`` does. If your query has more than one row,
+it returns the current row and moves the internal data pointer ahead. 
 
 ::
 
@@ -156,12 +156,19 @@ The result is returned as $type could be 'object' (default) or 'array' that will
 		echo $row->body;
 	}
 
+You can optionally pass 'object' (default) or 'array' in order to specify
+the returned value's type::
+
+	$query->unbuffered_row();		// object
+	$query->unbuffered_row('object');	// object
+	$query->unbuffered_row('array');	// associative array
+
 ***********************
 Result Helper Functions
 ***********************
 
 $query->num_rows()
-===================
+==================
 
 The number of rows returned by the query. Note: In this example, $query
 is the variable that the query result object is assigned to::
@@ -177,7 +184,7 @@ is the variable that the query result object is assigned to::
 	resulting array in order to achieve the same functionality.
 	
 $query->num_fields()
-=====================
+====================
 
 The number of FIELDS (columns) returned by the query. Make sure to call
 the function using your query result object::
@@ -187,7 +194,7 @@ the function using your query result object::
 	echo $query->num_fields();
 
 $query->free_result()
-======================
+=====================
 
 It frees the memory associated with the result and deletes the result
 resource ID. Normally PHP frees its memory automatically at the end of
@@ -209,3 +216,21 @@ Example::
 	$row = $query2->row();
 	echo $row->name;
 	$query2->free_result(); // The $query2 result object will no longer be available
+
+data_seek()
+===========
+
+This method sets the internal pointer for the next result row to be
+fetched. It is only useful in combination with ``unbuffered_row()``.
+
+It accepts a positive integer value, which defaults to 0 and returns
+TRUE on success or FALSE on failure.
+
+::
+
+	$query = $this->db->query('SELECT `field_name` FROM `table_name`');
+	$query->data_seek(5); // Skip the first 5 rows
+	$row = $query->unbuffered_row();
+
+.. note:: Not all database drivers support this feature and will return FALSE.
+	Most notably - you won't be able to use it with PDO.
\ No newline at end of file