You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
59 lines
2.1 KiB
59 lines
2.1 KiB
""" |
|
This module contains the spatial lookup types, and the `get_geo_where_clause` |
|
routine for MySQL. |
|
|
|
Please note that MySQL only supports bounding box queries, also |
|
known as MBRs (Minimum Bounding Rectangles). Moreover, spatial |
|
indices may only be used on MyISAM tables -- if you need |
|
transactions, take a look at PostGIS. |
|
""" |
|
from django.db import connection |
|
qn = connection.ops.quote_name |
|
|
|
# To ease implementation, WKT is passed to/from MySQL. |
|
GEOM_FROM_TEXT = 'GeomFromText' |
|
GEOM_FROM_WKB = 'GeomFromWKB' |
|
GEOM_SELECT = 'AsText(%s)' |
|
|
|
# WARNING: MySQL is NOT compliant w/the OpenGIS specification and |
|
# _every_ one of these lookup types is on the _bounding box_ only. |
|
MYSQL_GIS_FUNCTIONS = { |
|
'bbcontains' : 'MBRContains', # For consistency w/PostGIS API |
|
'bboverlaps' : 'MBROverlaps', # .. .. |
|
'contained' : 'MBRWithin', # .. .. |
|
'contains' : 'MBRContains', |
|
'disjoint' : 'MBRDisjoint', |
|
'equals' : 'MBREqual', |
|
'exact' : 'MBREqual', |
|
'intersects' : 'MBRIntersects', |
|
'overlaps' : 'MBROverlaps', |
|
'same_as' : 'MBREqual', |
|
'touches' : 'MBRTouches', |
|
'within' : 'MBRWithin', |
|
} |
|
|
|
# This lookup type does not require a mapping. |
|
MISC_TERMS = ['isnull'] |
|
|
|
# Assacceptable lookup types for Oracle spatial. |
|
MYSQL_GIS_TERMS = MYSQL_GIS_FUNCTIONS.keys() |
|
MYSQL_GIS_TERMS += MISC_TERMS |
|
MYSQL_GIS_TERMS = dict((term, None) for term in MYSQL_GIS_TERMS) # Making dictionary |
|
|
|
def get_geo_where_clause(table_alias, name, lookup_type, geo_annot): |
|
"Returns the SQL WHERE clause for use in MySQL spatial SQL construction." |
|
# Getting the quoted field as `geo_col`. |
|
geo_col = '%s.%s' % (qn(table_alias), qn(name)) |
|
|
|
# See if a MySQL Geometry function matches the lookup type next |
|
lookup_info = MYSQL_GIS_FUNCTIONS.get(lookup_type, False) |
|
if lookup_info: |
|
return "%s(%s, %%s)" % (lookup_info, geo_col) |
|
|
|
# Handling 'isnull' lookup type |
|
# TODO: Is this needed because MySQL cannot handle NULL |
|
# geometries in its spatial indices. |
|
if lookup_type == 'isnull': |
|
return "%s IS %sNULL" % (geo_col, (not geo_annot.value and 'NOT ' or '')) |
|
|
|
raise TypeError("Got invalid lookup_type: %s" % repr(lookup_type))
|
|
|