Fixed #13315, #13430 -- Recreated `django.contrib.gis.db.backend` module with `SpatialBackend` alias and added `Adaptor` alias for backwards-compatibility purposes; added GeoDjango 1.2 backwards-incompatibility documentation and release notes; added a section in the docs about how MySQL is a crippled spatial database; updated versions in install docs.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@13097 bcc190cf-cafb-0310-a4f2-bffc1f526a37

3 files changed, 189 insertions, 20 deletions

diff --git a/docs/ref/contrib/gis/db-api.txt b/docs/ref/contrib/gis/db-api.txt
index 0959156c43..6797ce2de0 100644
--- a/docs/ref/contrib/gis/db-api.txt
+++ b/docs/ref/contrib/gis/db-api.txt
@@ -23,13 +23,16 @@ its functionality into full-fledged spatial database backends:
 * :mod:`django.contrib.gis.db.backends.oracle`
 * :mod:`django.contrib.gis.db.backends.spatialite`
 
-Backwards-Compatibility
------------------------
+Database Settings Backwards-Compatibility
+-----------------------------------------
 
-For those using the old database settings (e.g., the ``DATABASE_*`` settings)
-Django 1.2 will automatically use the appropriate spatial backend as long
-as :mod:`django.contrib.gis` is in your :setting:`INSTALLED_APPS`.  For
-example, if you have the following in your settings::
+In :ref:`Django 1.2 <releases-1.2>`, the way 
+to :ref:`specify databases <specifying-databases>` in your settings was changed.
+The old database settings format (e.g., the ``DATABASE_*`` settings)
+is backwards compatible with GeoDjango, and  will automatically use the
+appropriate spatial backend as long as :mod:`django.contrib.gis` is in
+your :setting:`INSTALLED_APPS`.  For example, if you have the following in
+your settings::
 
     DATABASE_ENGINE='postgresql_psycopg2'
 
@@ -41,9 +44,37 @@ example, if you have the following in your settings::
       ...
     )
 
-Then, :mod:`django.contrib.gis.db.backends.postgis` will automatically be used as your
+Then, :mod:`django.contrib.gis.db.backends.postgis` is automatically used as your
 spatial backend.
 
+.. _mysql-spatial-limitations:
+
+MySQL Spatial Limitations
+-------------------------
+
+MySQL's spatial extensions only support bounding box operations
+(what MySQL calls minimum bounding rectangles, or MBR).  Specifically,
+`MySQL does not conform to the OGC standard <http://dev.mysql.com/doc/refman/5.1/en/functions-that-test-spatial-relationships-between-geometries.html>`_:
+
+    Currently, MySQL does not implement these functions
+    [``Contains``, ``Crosses``, ``Disjoint``, ``Intersects``, ``Overlaps``,
+    ``Touches``, ``Within``]
+    according to the specification.  Those that are implemented return
+    the same result as the corresponding MBR-based functions. 
+
+In other words, while spatial lookups such as :lookup:`contains <gis-contains>`
+are available in GeoDjango when using MySQL, the results returned are really
+equivalent to what would be returned when using :lookup:`bbcontains`
+on a different spatial backend.
+
+.. warning::
+
+    True spatial indexes (R-trees) are only supported with
+    MyISAM tables on MySQL. [#fnmysqlidx]_ In other words, when using
+    MySQL spatial extensions you have to choose between fast spatial
+    lookups and the integrity of your data -- MyISAM tables do
+    not support transactions or foreign key constraints.
+
 Creating and Saving Geographic Models
 =====================================
 Here is an example of how to create a geometry object (assuming the ``Zipcode``
@@ -307,4 +338,12 @@ Method                                PostGIS  Oracle  SpatiaLite
 .. [#fngeojson] *See* Howard Butler, Martin Daly, Allan Doyle, Tim Schaub, & Christopher Schmidt, `The GeoJSON Format Specification <http://geojson.org/geojson-spec.html>`_, Revision 1.0 (June 16, 2008).
 .. [#fndistsphere14] *See* `PostGIS 1.4 documentation <http://postgis.refractions.net/documentation/manual-1.4/ST_Distance_Sphere.html>`_ on ``ST_distance_sphere``.
 .. [#fndistsphere15] *See* `PostGIS 1.5 documentation <http://postgis.refractions.net/documentation/manual-1.5/ST_Distance_Sphere.html>`_ on ``ST_distance_sphere``.
-.. [#] MySQL only supports bounding box operations (known as minimum bounding rectangles, or MBR, in MySQL).  Thus, spatial lookups such as :lookup:`contains <gis-contains>` are really equivalent to :lookup:`bbcontains`.
+.. [#fnmysqlidx] *See* `Creating Spatial Indexes <http://dev.mysql.com/doc/refman/5.1/en/creating-spatial-indexes.html>`_
+   in the MySQL 5.1 Reference Manual:
+
+       For MyISAM tables, ``SPATIAL INDEX`` creates an R-tree index. For storage
+       engines that support nonspatial indexing of spatial columns, the engine
+       creates a B-tree index. A B-tree index on spatial values will be useful
+       for exact-value lookups, but not for range scans.
+
+.. [#] Refer :ref:`mysql-spatial-limitations` section for more details.
diff --git a/docs/ref/contrib/gis/install.txt b/docs/ref/contrib/gis/install.txt
index 55883d8ba5..00d4e62e9f 100644
--- a/docs/ref/contrib/gis/install.txt
+++ b/docs/ref/contrib/gis/install.txt
@@ -150,13 +150,13 @@ directly from Python using ctypes.
 First, download GEOS 3.2 from the refractions website and untar the source 
 archive::
 
-    $ wget http://download.osgeo.org/geos/geos-3.2.1.tar.bz2
-    $ tar xjf geos-3.2.1.tar.bz2
+    $ wget http://download.osgeo.org/geos/geos-3.2.2.tar.bz2
+    $ tar xjf geos-3.2.2.tar.bz2
 
 Next, change into the directory where GEOS was unpacked, run the configure 
 script, compile, and install::
 
-    $ cd geos-3.2.1
+    $ cd geos-3.2.2
     $ ./configure
     $ make
     $ sudo make install
@@ -273,9 +273,9 @@ supports :ref:`GDAL's vector data <ref-gdal>` capabilities [#]_.
 
 First download the latest GDAL release version and untar the archive::
 
-    $ wget http://download.osgeo.org/gdal/gdal-1.7.1.tar.gz
-    $ tar xzf gdal-1.7.1.tar.gz
-    $ cd gdal-1.7.1
+    $ wget http://download.osgeo.org/gdal/gdal-1.7.2.tar.gz
+    $ tar xzf gdal-1.7.2.tar.gz
+    $ cd gdal-1.7.2
 
 Configure, make and install::
 
@@ -516,9 +516,9 @@ user.  For example, you can use the following to become the ``postgres`` user::
 
    The location *and* name of the PostGIS SQL files (e.g., from
    ``POSTGIS_SQL_PATH`` below) depends on the version of PostGIS.
-   PostGIS versions 1.3 and below use ``<sharedir>/contrib/lwpostgis.sql``, whereas
-   versions 1.4 and 1.5 use ``<sharedir>/contrib/postgis-1.4/postgis.sql`` and
-   ``<sharedir>/contrib/postgis-1.5/postgis.sql``, respectively.
+   PostGIS versions 1.3 and below use ``<pg_sharedir>/contrib/lwpostgis.sql``;
+   whereas version 1.4 uses ``<sharedir>/contrib/postgis.sql`` and
+   version 1.5 uses ``<sharedir>/contrib/postgis-1.5/postgis.sql``.
 
    The example below assumes PostGIS 1.5, thus you may need to modify
    ``POSTGIS_SQL_PATH`` and the name of the SQL file for the specific 
diff --git a/docs/releases/1.2.txt b/docs/releases/1.2.txt
index 31b95e4ace..e8370c2b4b 100644
--- a/docs/releases/1.2.txt
+++ b/docs/releases/1.2.txt
@@ -77,6 +77,9 @@ changes:
 
        __members__ = property(lambda self: self.__dir__())
 
+
+.. _specifying-databases:
+
 Specifying databases
 --------------------
 
@@ -338,8 +341,6 @@ you need an unmodified instance of your model, you should pass a copy to the
 ``ModelForm`` constructor.
 
 
-.. _deprecated-features-1.2:
-
 ``BooleanField`` on MySQL
 --------------------------
 
@@ -350,6 +351,8 @@ people this shouldn't have been a problem because ``bool`` is a subclass of
 only time this should ever be an issue is if you were expecting printing the
 ``repr`` of a ``BooleanField`` to print ``1`` or ``0``.
 
+.. _deprecated-features-1.2:
+
 Features deprecated in 1.2
 ==========================
 
@@ -363,7 +366,7 @@ library, has been deprecated.
 If you are currently using the ``postgresql`` backend, you should
 migrate to using the ``postgresql_psycopg2`` backend. To update your
 code, install the ``psycopg2`` library and change the
-``DATABASE_ENGINE`` setting to read ``postgresql_psycopg2``.
+:setting:`DATABASE_ENGINE` setting to read ``postgresql_psycopg2``.
 
 CSRF response-rewriting middleware
 ----------------------------------
@@ -594,6 +597,88 @@ deprecated in favor of the new :ref:`Format localization
 information in a ``formats.py`` file in the corresponding
 ``django/conf/locale/<locale name>/`` directory.
 
+GeoDjango
+---------
+
+To allow support for multiple databases, the GeoDjango database internals were
+changed substantially.  The largest backwards-incompatible change is that
+the module ``django.contrib.gis.db.backend`` was renamed to
+:mod:`django.contrib.gis.db.backends`, where the full-fledged
+:ref:`spatial databased backends <spatial-backends>` now exist.  The
+following sections provide information on the most-popular APIs that
+were affected by these changes.
+
+``SpatialBackend``
+^^^^^^^^^^^^^^^^^^
+
+Prior to the creation of the separate spatial backends, the 
+``django.contrib.gis.db.backend.SpatialBackend`` object was
+provided as an abstraction to introspect on the capabilities of
+the spatial database.  All of the attributes and routines provided by
+``SpatialBackend`` are now a part of the ``ops`` attribute of the
+database backend.
+
+The old module ``django.contrib.gis.db.backend`` is still provided
+for backwards-compatibility access to a ``SpatialBackend`` object,
+which is just an alias to the ``ops`` module of the
+*default* spatial database connection.
+
+Users that were relying on undocumented modules and objects
+within ``django.contrib.gis.db.backend``, rather the abstractions
+provided by ``SpatialBackend``, are required to modify their code.
+For example, the following import which would work in 1.1 and
+below::
+
+    from django.contrib.gis.db.backend.postgis import PostGISAdaptor
+
+Would need to be changed::
+
+    from django.db import connection
+    PostGISAdaptor = connection.ops.Adapter
+
+``SpatialRefSys`` and ``GeometryColumns`` models
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+In previous versions of GeoDjango, :mod:`django.contrib.gis.db.models`
+had ``SpatialRefSys`` and ``GeometryColumns`` models for querying
+the OGC spatial metadata tables ``spatial_ref_sys`` and ``geometry_columns``,
+respectively.
+
+While these aliases are still provided, they are only for the
+*default* database connection and exist only if the default connection
+is using a supported spatial database backend.
+
+.. note::
+
+    Because the table structure of the OGC spatial metadata tables
+    differs across spatial databases, the ``SpatialRefSys`` and
+    ``GeometryColumns`` models can no longer be associated with
+    the ``gis`` application name.  Thus, no models will be returned
+    when using the ``get_models`` method in the following example::
+
+        >>> from django.db.models import get_app, get_models
+        >>> get_models(get_app('gis'))
+        []
+
+To get the correct ``SpatialRefSys`` and ``GeometryColumns``
+for your spatial database use the methods provided by the spatial backend::
+
+     >>> from django.db import connections
+     >>> SpatialRefSys = connections['my_spatialite'].ops.spatial_ref_sys()
+     >>> GeometryColumns = connections['my_postgis'].ops.geometry_columns()
+
+.. note::
+
+    When using the models returned from the ``spatial_ref_sys()`` and
+    ``geometry_columns()`` method, you'll still need to use the
+    correct database alias when querying on the non-default connection.
+    In other words, to ensure that the models in the example above
+    use the correct database::
+
+        sr_qs = SpatialRefSys.objects.using('my_spatialite').filter(...)
+        gc_qs = GeometryColumns.objects.using('my_postgis').filter(...)
+
+
 What's new in Django 1.2
 ========================
 
@@ -793,6 +878,51 @@ The built-in :class:`~django.contrib.auth.models.User` model's
 :attr:`~django.contrib.auth.models.User.username` field now allows a wider range
 of characters, including ``@``, ``+``, ``.`` and ``-`` characters.
 
+GeoDjango
+---------
+
+In 1.2, :ref:`GeoDjango <ref-contrib-gis>` was upgraded to provide
+support for multiple spatial databases.  As a result, the following 
+:ref:`spatial database backends <spatial-backends>`
+are now included:
+
+* :mod:`django.contrib.gis.db.backends.postgis`
+* :mod:`django.contrib.gis.db.backends.mysql`
+* :mod:`django.contrib.gis.db.backends.oracle`
+* :mod:`django.contrib.gis.db.backends.spatialite`
+
+GeoDjango now supports the rich capabilities added
+in the `PostGIS 1.5 release <http://postgis.refractions.net/documentation/manual-1.5/>`_.
+New features include suppport for the the :ref:`geography type <geography-type>`
+and enabling of :ref:`distance queries <distance-queries>`
+with non-point geometries on geographic coordinate systems.
+
+Support for 3D geometry fields was added, and may be enabled
+by setting the :attr:`~django.contrib.gis.db.models.GeometryField.dim`
+keyword to 3 in your :class:`~django.contrib.gis.db.models.GeometryField`.
+The :class:`~django.contrib.gis.db.models.Extent3D` aggregate
+and :meth:`~django.contrib.gis.db.models.GeoQuerySet.extent3d` ``GeoQuerySet``
+method were added as a part of this feature.
+
+The following :class:`~django.contrib.gis.db.models.GeoQeurySet`
+methods are new in 1.2:
+
+* :meth:`~django.contrib.gis.db.models.GeoQuerySet.force_rhr`
+* :meth:`~django.contrib.gis.db.models.GeoQuerySet.reverse_geom`
+* :meth:`~django.contrib.gis.db.models.GeoQuerySet.geohash`
+
+The :ref:`GEOS interface <ref-geos>` was updated to use
+thread-safe C library functions when available on the platform.
+
+The :ref:`GDAL interface <ref-gdal>` now allows the user to place
+set a :attr:`~django.contrib.gis.gdal.Layer.spatial_filter` on
+the features returned from a :class:`~django.contrib.gis.gdal.DataSource`
+:class:`~django.contrib.gis.gdal.Layer`.
+
+Finally, :ref:`GeoDjango's documentation <ref-contrib-gis>` is now
+included with Django's and is no longer
+hosted separately at `geodjango.org <http://geodjango.org/>`_.
+
 Deprecation of old language code ``no``
 ---------------------------------------