gis: Modifications to Django management commands to support creation of spatial tables.

[jbronn]

This patch contains the following changes that enable the Django management commands to construct spatial SQL for PostGIS:

1. The addition of the _post_create_sql hook. If a custom field has this function it will be called and its output will precede any other SQL generated by sql.custom_sql_for_model. This works well, but I'm of course open to changes in the function name and/or the possibility of a post_table_create signal or something (doing after post_syncdb will not work).

2. Although not required for GeoDjango having custom_sql_for_model take the style object as a parameter allows for colorizing the generated spatial SQL -- the sqlcustom and syncdb commands are modified to pass in their style object to custom_sql_for_model.

[jbronn]

Modification of Django management commands to support GeoDjango

[Malcolm Tredinnick]

(In [8133]) Fixed #7589 -- Added a way for post-table-creation SQL modifications to be done for custom fields (needed by geo-django, but useful in other situations, too).

Patch from Justin Bronn.

[Malcolm Tredinnick]

Since field classes aren't going to have their namespace populated by general user code, I removed the leading underscore from your method. It's now just post_create_sql(). I also made a slight tweak to the way you checked for fields declared directly on the object that looks equivalent to what you were attempting, but just double-check I haven't missed something.

[Jacob]

Milestone 1.0 beta deleted