66 lines
2.6 KiB
Python
66 lines
2.6 KiB
Python
from django.db.backends.postgresql.schema import DatabaseSchemaEditor
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class PostGISSchemaEditor(DatabaseSchemaEditor):
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geom_index_type = 'GIST'
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geom_index_ops_nd = 'GIST_GEOMETRY_OPS_ND'
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rast_index_wrapper = 'ST_ConvexHull(%s)'
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sql_alter_column_to_3d = "ALTER COLUMN %(column)s TYPE %(type)s USING ST_Force3D(%(column)s)::%(type)s"
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sql_alter_column_to_2d = "ALTER COLUMN %(column)s TYPE %(type)s USING ST_Force2D(%(column)s)::%(type)s"
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def geo_quote_name(self, name):
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return self.connection.ops.geo_quote_name(name)
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def _field_should_be_indexed(self, model, field):
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if getattr(field, 'spatial_index', False):
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return True
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return super()._field_should_be_indexed(model, field)
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def _create_index_sql(self, model, fields, **kwargs):
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if len(fields) != 1 or not hasattr(fields[0], 'geodetic'):
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return super()._create_index_sql(model, fields, **kwargs)
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field = fields[0]
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field_column = self.quote_name(field.column)
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if field.geom_type == 'RASTER':
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# For raster fields, wrap index creation SQL statement with ST_ConvexHull.
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# Indexes on raster columns are based on the convex hull of the raster.
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field_column = self.rast_index_wrapper % field_column
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elif field.dim > 2 and not field.geography:
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# Use "nd" ops which are fast on multidimensional cases
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field_column = "%s %s" % (field_column, self.geom_index_ops_nd)
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return self.sql_create_index % {
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"name": self.quote_name('%s_%s_id' % (model._meta.db_table, field.column)),
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"table": self.quote_name(model._meta.db_table),
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"using": "USING %s" % self.geom_index_type,
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"columns": field_column,
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"extra": '',
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}
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def _alter_column_type_sql(self, table, old_field, new_field, new_type):
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"""
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Special case when dimension changed.
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"""
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if not hasattr(old_field, 'dim') or not hasattr(new_field, 'dim'):
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return super()._alter_column_type_sql(table, old_field, new_field, new_type)
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if old_field.dim == 2 and new_field.dim == 3:
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sql_alter = self.sql_alter_column_to_3d
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elif old_field.dim == 3 and new_field.dim == 2:
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sql_alter = self.sql_alter_column_to_2d
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else:
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sql_alter = self.sql_alter_column_type
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return (
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(
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sql_alter % {
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"column": self.quote_name(new_field.column),
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"type": new_type,
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},
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[],
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),
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[],
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)
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