Add OGC-compliant models for GeoDjango running on MySQL 8.0

[Jeff Hitchcock]

MySQL 8 introduced two new tables that allow the implementation of the SpatialRefSys and GeometryColumns models as well as related functions for adding new SRS entries to the database. Adding these two models and updating related functions to support them would be a good first step to improving GeoDjango's support for MySQL 8.

• Add MySQLSpatialRefSys model connecting to the INFORMATION_SCHEMA.ST_SPATIAL_REFERENCE_SYSTEMS table (​https://dev.mysql.com/doc/refman/8.0/en/information-schema-st-spatial-reference-systems-table.html)
• Add MySQLGeometryColumns model connecting to the INFORMATION_SCHEMA.ST_GEOMETRY_COLUMNS table (​https://dev.mysql.com/doc/refman/8.0/en/information-schema-st-geometry-columns-table.html)
• Enable has_spatialrefsys_table and supports_add_srs_entry backend features if MySQL version is greater than 8.0

[Mariusz Felisiak]

Thanks for the report.

#27464 is probably a partially duplicate of this ticket. What do you think?

[Jeff Hitchcock]

Replying to Mariusz Felisiak:

#27464 is probably a partially duplicate of this ticket. What do you think?

They are definitely related, but that ticket has more to do with setting SRID on columns (aka support for ALTER TABLE _ ADD pt POINT SRID 4326) while this deals with being able to add new SRS entries into the database (MySQLSpatialRefSys and add_srs_entry) and introspection of columns that have spatial information (MySQLGeometryColumns).

[karthikeyaa-dev]

I'm working on this ticket.

[Jacob Walls]

This work is a prerequisite for adding support for the Transform function (#37320), which is in turn a prerequisite for implementing an upgrade path to having GeoDjango able to read/write to SRID-aware columns in #27464.

We will need to be careful to not retain the has_spatialrefsys_table flag as a gate for whether to read/write SRID 0, because that work needs to be done in #27464.

[Md. Saikat Islam]

Since PR(​https://github.com/django/django/pull/20923) is closed due to inactivity. I will be taking this from here.