OGR/PHP Extension

Introduction

The OGR library is a C++ open source library (and command-line tools) providing read (and sometimes write) access to a variety of vector file formats including ESRI Shapefiles, S-57, SDTS, PostGIS, Oracle Spatial, and Mapinfo mid/mif and TAB formats.

The C API is generally easy to call from other languages which allow call out to DLLs functions, such as Visual Basic, or Delphi.

The OGR/PHP extension enables PHP users to access the functionalities included in the OGR library. This extension can be used as built-in PHP or as dynamic library (".dll" on Windows or ".so" on Unix).

This extension was developed and is currently being maintained by DM Solutions Group. Special thanks go to Lars V. Nielsen and Hvenegaard & Meklenborg for funding the initial development of this extension and allowing it to remain open source.

Download

To use the OGR/PHP extension, the following is needed:

PHP 4.2.3 or higher
Note that for PHP 5.x, OGR/PHP 1.1.1 is required.
GDAL library 1.1.8
Note from OGR/PHP version 1.1.0, GDAL 1.3.0 is required.
OGR/PHP extension module

PHP

Check if you have PHP already installed (several Linux distributions have it built in).
If not, download the 4.2.3 or higher PHP version source code or binaries.

Source code and win32 binaries are available on the PHP download page.

The PHP source code is also available via anonymous CVS, see the PHP cvs page.

GDAL/OGR

Visit the GDAL website to download the latest version of the library.

OGR/PHP

Source code or Win32 dll for the OGR/PHP extension can be obtained from DM Solutions. The official download location is still to be determined.

Build/Installation/Test

GDAL

GDAL library must be built before compiling PHP and OGR/PHP extension.

Currently a build mechanism only exists for Unix, and the C wrapper functions are built and installed as a standard part of GDAL/OGR. It does live in the GDAL/OGR source tree.

The source (such as a nightly CVS snapshot) can be downloaded from the GDAL/OGR web site.
Once unpacked, build GDAL/OGR according to the provided instructions, and then install.

% cd gdal
% ./configure
...
% make
% sudo make install

PHP - OGR/PHP

Building on Unix

Recommendation

There are two ways to build the OGR/PHP extension: as a separate module (as a ".so" library) or as a built-in module. It is recommended to use this extension as a separate module for simplicity reason and because there is no need to compile PHP.

Build as a separate module

tar xzvf php_ogr_1.0.tar.gz into the "ext" directory.
Run /path/to/phpize in the OGR/PHP extension source directory.
Run ./configure --with-php-config=/path/to/php-config.
Run make in the OGR/PHP extension directory.
Change directory to "modules" under OGR/PHP extension.
Copy the ogr.so library to your PHP extensions directory.
Rename the extension "php_ogr.so".
Use dl() function to load the module at the beginning of your PHP scripts.

Build as a built-in module

Installed the PHP source code if not already installed.
tar xzvf php_ogr_1.0.tar.gz into the "ext" directory.
Run ./buildconf --force in the PHP main directory.
Run ./configure --with-ogr[=dir] in the PHP main directory where dir is corresponding to the GDAL/OGR directory.
Run make in the PHP main directory.
PHP is now compiled with OGR/PHP built-in.

More information can be found into the PHP manual.

Installing on Windows

Unzip php-4.x.x-Win32.zip into your prefered folder and follow the install instruction.
Unzip php_ogr_1.0.zip.
Copy the 'dll' into your extensions library folder.

Testing all

To verify that PHP and OGR/PHP were installed properly, create a '.php' file containing the following code and try to access it through your web server:

       <?php
       if (PHP_OS == "WINNT" || PHP_OS == "WIN32")
       {
         dl("php_ogr.dll");
       }
       else
       {
         dl("php_ogr.so");
       }
       phpinfo();
       ?>

</BODY>
</HTML>

If PHP and PHP/OGR were installed properly, several tables should be displayed on your page, and 'OGR' should be listed in the 'Extensions' table.

Functions documentation

The C API documentation was created using Doxygen and is part of the GDAL/OGR documentation. In addition to OGR functions, four CPL functions for handling error are made available to the user: CPLErrorReset, CPLGetLastErrorNo, CPLGetLastErrorMsg and CPLGetLastErrorType. Information on these functions can be found on this page.

Information and bug reporting

The OGR mailing list can be used for discussion of developement and user issues related to OGR and related technology. Mailing list can be used to report bugs as well. Subscriptions can be done, and archives reviewed on the web.

Examples

There are a few examples showing how to use the functions in the PHP/OGR extension module. Consult the README_EXAMPLES.TXT in the examples sub-directory of the extension package to get more information on what is the purpose of each example.

Each example must be invoked from the command-line.

Example: ./php -q ogr2tab.php /path/to/outputfilename.tab /path/to/sourcefilename.tab

"ogr2ogr.php" shows mostly the following:

Opening an existing data source with a specific driver
Creating a new data source
Accessing a layer
Creating a new layer
Adding fields on a layer
Getting features from a layer
Creating new features on a layer
Testing capabilities of a data source or a layer

"ogr2tab.php" is accomplishing the same operations as "ogr2ogr.php" but is concerned especially with the MapInfo File format.

"ogr_spatialfilter.php" shows mostly how to set a spatial filter and an attribute filter.

"ogr2tab_spatialfilter.php" is accomplishing the same operations as "ogr_spatialfilter.php" but is used exclusively with MapInfo File format.

"ogr_sql.php" demonstrates how to build an SQL statement and apply an SQL request to a data source.

"ogr2tab_sql.php" is a copy of "ogr_sql.php" and is concerned with the MapInfo File format.

"ogr_update.php" demonstrates the following items:

Accessing a specific feature by specifying a feature id
Getting a field definition
Getting a field name
Setting a field value
Getting a geometry from a feature
Setting a geometry to a feature

"ogr2tab_update.php" is a copy of "ogr_update.php" but is concerned with the MapInfo File format.

"ogr_dump.php" shows the following functionalities:

Getting geometry components from which geometry is built from, like point coordinates for a linestring, linestring for a polygon and so on
Getting geometry name
Getting the number of geometry components

"ogr_write.php" demonstrates the following functionalities:

Accessing a specific layer
Creating a new field definition and assigning it to a layer
Creating a new feature on a layer
Setting a field value
Creating a new geometry (point, linestring, polygon) and adding it to a feature

"ogr_setgetfield.php" shows how to get and to set field values of various types inside a feature.