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

(as requested in #2050)

2 files changed, 39 insertions, 12 deletions

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