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from itertools import izip
from django.db.backends.util import truncate_name
from django.db.models.sql import compiler
from django.db.models.sql.constants import TABLE_NAME
from django.db.models.sql.query import get_proxied_model
SQLCompiler = compiler.SQLCompiler
class GeoSQLCompiler(compiler.SQLCompiler):
def get_columns(self, with_aliases=False):
"""
Return the list of columns to use in the select statement. If no
columns have been specified, returns all columns relating to fields in
the model.
If 'with_aliases' is true, any column names that are duplicated
(without the table names) are given unique aliases. This is needed in
some cases to avoid ambiguitity with nested queries.
This routine is overridden from Query to handle customized selection of
geometry columns.
"""
qn = self.quote_name_unless_alias
qn2 = self.connection.ops.quote_name
result = ['(%s) AS %s' % (self.get_extra_select_format(alias) % col[0], qn2(alias))
for alias, col in self.query.extra_select.iteritems()]
aliases = set(self.query.extra_select.keys())
if with_aliases:
col_aliases = aliases.copy()
else:
col_aliases = set()
if self.query.select:
only_load = self.deferred_to_columns()
# This loop customized for GeoQuery.
for col, field in izip(self.query.select, self.query.select_fields):
if isinstance(col, (list, tuple)):
alias, column = col
table = self.query.alias_map[alias][TABLE_NAME]
if table in only_load and col not in only_load[table]:
continue
r = self.get_field_select(field, alias, column)
if with_aliases:
if col[1] in col_aliases:
c_alias = 'Col%d' % len(col_aliases)
result.append('%s AS %s' % (r, c_alias))
aliases.add(c_alias)
col_aliases.add(c_alias)
else:
result.append('%s AS %s' % (r, qn2(col[1])))
aliases.add(r)
col_aliases.add(col[1])
else:
result.append(r)
aliases.add(r)
col_aliases.add(col[1])
else:
result.append(col.as_sql(qn, self.connection))
if hasattr(col, 'alias'):
aliases.add(col.alias)
col_aliases.add(col.alias)
elif self.query.default_cols:
cols, new_aliases = self.get_default_columns(with_aliases,
col_aliases)
result.extend(cols)
aliases.update(new_aliases)
max_name_length = self.connection.ops.max_name_length()
result.extend([
'%s%s' % (
self.get_extra_select_format(alias) % aggregate.as_sql(qn, self.connection),
alias is not None
and ' AS %s' % qn(truncate_name(alias, max_name_length))
or ''
)
for alias, aggregate in self.query.aggregate_select.items()
])
# This loop customized for GeoQuery.
for (table, col), field in izip(self.query.related_select_cols, self.query.related_select_fields):
r = self.get_field_select(field, table, col)
if with_aliases and col in col_aliases:
c_alias = 'Col%d' % len(col_aliases)
result.append('%s AS %s' % (r, c_alias))
aliases.add(c_alias)
col_aliases.add(c_alias)
else:
result.append(r)
aliases.add(r)
col_aliases.add(col)
self._select_aliases = aliases
return result
def get_default_columns(self, with_aliases=False, col_aliases=None,
start_alias=None, opts=None, as_pairs=False, local_only=False):
"""
Computes the default columns for selecting every field in the base
model. Will sometimes be called to pull in related models (e.g. via
select_related), in which case "opts" and "start_alias" will be given
to provide a starting point for the traversal.
Returns a list of strings, quoted appropriately for use in SQL
directly, as well as a set of aliases used in the select statement (if
'as_pairs' is True, returns a list of (alias, col_name) pairs instead
of strings as the first component and None as the second component).
This routine is overridden from Query to handle customized selection of
geometry columns.
"""
result = []
if opts is None:
opts = self.query.model._meta
aliases = set()
only_load = self.deferred_to_columns()
# Skip all proxy to the root proxied model
proxied_model = get_proxied_model(opts)
if start_alias:
seen = {None: start_alias}
for field, model in opts.get_fields_with_model():
if local_only and model is not None:
continue
if start_alias:
try:
alias = seen[model]
except KeyError:
if model is proxied_model:
alias = start_alias
else:
link_field = opts.get_ancestor_link(model)
alias = self.query.join((start_alias, model._meta.db_table,
link_field.column, model._meta.pk.column))
seen[model] = alias
else:
# If we're starting from the base model of the queryset, the
# aliases will have already been set up in pre_sql_setup(), so
# we can save time here.
alias = self.query.included_inherited_models[model]
table = self.query.alias_map[alias][TABLE_NAME]
if table in only_load and field.column not in only_load[table]:
continue
if as_pairs:
result.append((alias, field.column))
aliases.add(alias)
continue
# This part of the function is customized for GeoQuery. We
# see if there was any custom selection specified in the
# dictionary, and set up the selection format appropriately.
field_sel = self.get_field_select(field, alias)
if with_aliases and field.column in col_aliases:
c_alias = 'Col%d' % len(col_aliases)
result.append('%s AS %s' % (field_sel, c_alias))
col_aliases.add(c_alias)
aliases.add(c_alias)
else:
r = field_sel
result.append(r)
aliases.add(r)
if with_aliases:
col_aliases.add(field.column)
return result, aliases
def resolve_columns(self, row, fields=()):
"""
This routine is necessary so that distances and geometries returned
from extra selection SQL get resolved appropriately into Python
objects.
"""
values = []
aliases = self.query.extra_select.keys()
if self.query.aggregates:
# If we have an aggregate annotation, must extend the aliases
# so their corresponding row values are included.
aliases.extend([None for i in xrange(len(self.query.aggregates))])
# Have to set a starting row number offset that is used for
# determining the correct starting row index -- needed for
# doing pagination with Oracle.
rn_offset = 0
if self.connection.ops.oracle:
if self.query.high_mark is not None or self.query.low_mark: rn_offset = 1
index_start = rn_offset + len(aliases)
# Converting any extra selection values (e.g., geometries and
# distance objects added by GeoQuerySet methods).
values = [self.query.convert_values(v,
self.query.extra_select_fields.get(a, None),
self.connection)
for v, a in izip(row[rn_offset:index_start], aliases)]
if self.connection.ops.oracle or getattr(self.query, 'geo_values', False):
# We resolve the rest of the columns if we're on Oracle or if
# the `geo_values` attribute is defined.
for value, field in map(None, row[index_start:], fields):
values.append(self.query.convert_values(value, field, connection=self.connection))
else:
values.extend(row[index_start:])
return tuple(values)
#### Routines unique to GeoQuery ####
def get_extra_select_format(self, alias):
sel_fmt = '%s'
if alias in self.query.custom_select:
sel_fmt = sel_fmt % self.query.custom_select[alias]
return sel_fmt
def get_field_select(self, field, alias=None, column=None):
"""
Returns the SELECT SQL string for the given field. Figures out
if any custom selection SQL is needed for the column The `alias`
keyword may be used to manually specify the database table where
the column exists, if not in the model associated with this
`GeoQuery`. Similarly, `column` may be used to specify the exact
column name, rather than using the `column` attribute on `field`.
"""
sel_fmt = self.get_select_format(field)
if field in self.query.custom_select:
field_sel = sel_fmt % self.query.custom_select[field]
else:
field_sel = sel_fmt % self._field_column(field, alias, column)
return field_sel
def get_select_format(self, fld):
"""
Returns the selection format string, depending on the requirements
of the spatial backend. For example, Oracle and MySQL require custom
selection formats in order to retrieve geometries in OGC WKT. For all
other fields a simple '%s' format string is returned.
"""
if self.connection.ops.select and hasattr(fld, 'geom_type'):
# This allows operations to be done on fields in the SELECT,
# overriding their values -- used by the Oracle and MySQL
# spatial backends to get database values as WKT, and by the
# `transform` method.
sel_fmt = self.connection.ops.select
# Because WKT doesn't contain spatial reference information,
# the SRID is prefixed to the returned WKT to ensure that the
# transformed geometries have an SRID different than that of the
# field -- this is only used by `transform` for Oracle and
# SpatiaLite backends.
if self.query.transformed_srid and ( self.connection.ops.oracle or
self.connection.ops.spatialite ):
sel_fmt = "'SRID=%d;'||%s" % (self.query.transformed_srid, sel_fmt)
else:
sel_fmt = '%s'
return sel_fmt
# Private API utilities, subject to change.
def _field_column(self, field, table_alias=None, column=None):
"""
Helper function that returns the database column for the given field.
The table and column are returned (quoted) in the proper format, e.g.,
`"geoapp_city"."point"`. If `table_alias` is not specified, the
database table associated with the model of this `GeoQuery` will be
used. If `column` is specified, it will be used instead of the value
in `field.column`.
"""
if table_alias is None: table_alias = self.query.model._meta.db_table
return "%s.%s" % (self.quote_name_unless_alias(table_alias),
self.connection.ops.quote_name(column or field.column))
class SQLInsertCompiler(compiler.SQLInsertCompiler, GeoSQLCompiler):
pass
class SQLDeleteCompiler(compiler.SQLDeleteCompiler, GeoSQLCompiler):
pass
class SQLUpdateCompiler(compiler.SQLUpdateCompiler, GeoSQLCompiler):
pass
class SQLAggregateCompiler(compiler.SQLAggregateCompiler, GeoSQLCompiler):
pass
class SQLDateCompiler(compiler.SQLDateCompiler, GeoSQLCompiler):
pass
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