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Code Issues 32 Releases Wiki Activity

Added a "depth" argument to select_related() to control how many "levels" of relations select_related() is willing to follow (refs #3275).

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Also added unit tests for select_related().

git-svn-id: http://code.djangoproject.com/svn/django/trunk@4645 bcc190cf-cafb-0310-a4f2-bffc1f526a37
This commit is contained in:
Jacob Kaplan-Moss
2007-02-28 15:24:05 +00:00
parent 9c67c1dd8d
commit 4477f50f0b
4 changed files with 193 additions and 10 deletions
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38
django/db/models/query.py
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@@ -84,6 +84,7 @@ class QuerySet(object):
self._filters = Q()
self._order_by = None # Ordering, e.g. ('date', '-name'). If None, use model's ordering.
self._select_related = False # Whether to fill cache for related objects.
self._max_related_depth = 0 # Maximum "depth" for select_related
self._distinct = False # Whether the query should use SELECT DISTINCT.
self._select = {} # Dictionary of attname -> SQL.
self._where = [] # List of extra WHERE clauses to use.
@@ -186,7 +187,8 @@ class QuerySet(object):
raise StopIteration
for row in rows:
if fill_cache:
obj, index_end = get_cached_row(self.model, row, 0)
obj, index_end = get_cached_row(klass=self.model, row=row,
index_start=0, max_depth=self._max_related_depth)
else:
obj = self.model(*row[:index_end])
for i, k in enumerate(extra_select):
@@ -394,9 +396,9 @@ class QuerySet(object):
else:
return self._filter_or_exclude(None, **filter_obj)
def select_related(self, true_or_false=True):
def select_related(self, true_or_false=True, depth=0):
"Returns a new QuerySet instance with '_select_related' modified."
return self._clone(_select_related=true_or_false)
return self._clone(_select_related=true_or_false, _max_related_depth=depth)
def order_by(self, *field_names):
"Returns a new QuerySet instance with the ordering changed."
@@ -430,6 +432,7 @@ class QuerySet(object):
c._filters = self._filters
c._order_by = self._order_by
c._select_related = self._select_related
c._max_related_depth = self._max_related_depth
c._distinct = self._distinct
c._select = self._select.copy()
c._where = self._where[:]
@@ -483,7 +486,10 @@ class QuerySet(object):
# Add additional tables and WHERE clauses based on select_related.
if self._select_related:
fill_table_cache(opts, select, tables, where, opts.db_table, [opts.db_table])
fill_table_cache(opts, select, tables, where,
old_prefix=opts.db_table,
cache_tables_seen=[opts.db_table],
max_depth=self._max_related_depth)
# Add any additional SELECTs.
if self._select:
@@ -728,21 +734,33 @@ def get_where_clause(lookup_type, table_prefix, field_name, value):
return backend.get_fulltext_search_sql(table_prefix + field_name)
raise TypeError, "Got invalid lookup_type: %s" % repr(lookup_type)
def get_cached_row(klass, row, index_start):
"Helper function that recursively returns an object with cache filled"
def get_cached_row(klass, row, index_start, max_depth=0, cur_depth=0):
"""Helper function that recursively returns an object with cache filled"""
# If we've got a max_depth set and we've exceeded that depth, bail now.
if max_depth and cur_depth > max_depth:
return None
index_end = index_start + len(klass._meta.fields)
obj = klass(*row[index_start:index_end])
for f in klass._meta.fields:
if f.rel and not f.null:
rel_obj, index_end = get_cached_row(f.rel.to, row, index_end)
setattr(obj, f.get_cache_name(), rel_obj)
cached_row = get_cached_row(f.rel.to, row, index_end, max_depth, cur_depth+1)
if cached_row:
rel_obj, index_end = cached_row
setattr(obj, f.get_cache_name(), rel_obj)
return obj, index_end
def fill_table_cache(opts, select, tables, where, old_prefix, cache_tables_seen):
def fill_table_cache(opts, select, tables, where, old_prefix, cache_tables_seen, max_depth=0, cur_depth=0):
"""
Helper function that recursively populates the select, tables and where (in
place) for select_related queries.
"""
# If we've got a max_depth set and we've exceeded that depth, bail now.
if max_depth and cur_depth > max_depth:
return None
qn = backend.quote_name
for f in opts.fields:
if f.rel and not f.null:
@@ -757,7 +775,7 @@ def fill_table_cache(opts, select, tables, where, old_prefix, cache_tables_seen)
where.append('%s.%s = %s.%s' % \
(qn(old_prefix), qn(f.column), qn(db_table), qn(f.rel.get_related_field().column)))
select.extend(['%s.%s' % (qn(db_table), qn(f2.column)) for f2 in f.rel.to._meta.fields])
fill_table_cache(f.rel.to._meta, select, tables, where, db_table, cache_tables_seen)
fill_table_cache(f.rel.to._meta, select, tables, where, db_table, cache_tables_seen, max_depth, cur_depth+1)
def parse_lookup(kwarg_items, opts):
# Helper function that handles converting API kwargs