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[Backport] Improving neighbor calculation

remotes/origin/logger
Alejandro Alonso 2015-12-11 11:47:20 +01:00 committed by David Barragán Merino
parent 1a1afa0d0f
commit 5bf1036d2a
1 changed files with 23 additions and 8 deletions
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31
taiga/base/neighbors.py
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@ -18,7 +18,8 @@
from collections import namedtuple from collections import namedtuple
from django.db import connection from django.db import connection
from django.core.exceptions import ObjectDoesNotExist
from django.db.models.sql.datastructures import EmptyResultSet
from taiga.base.api import serializers from taiga.base.api import serializers
Neighbor = namedtuple("Neighbor", "left right") Neighbor = namedtuple("Neighbor", "left right")
@ -35,15 +36,27 @@ def get_neighbors(obj, results_set=None):
:return: Tuple `<left neighbor>, <right neighbor>`. Left and right neighbors can be `None`. :return: Tuple `<left neighbor>, <right neighbor>`. Left and right neighbors can be `None`.
""" """
if results_set is None or results_set.count() == 0: if results_set is None:
results_set = type(obj).objects.get_queryset() results_set = type(obj).objects.get_queryset()
# Neighbors calculation is at least at project level
results_set = results_set.filter(project_id=obj.project.id)
compiler = results_set.query.get_compiler('default') compiler = results_set.query.get_compiler('default')
base_sql, base_params = compiler.as_sql(with_col_aliases=True) try:
base_sql, base_params = compiler.as_sql(with_col_aliases=True)
except EmptyResultSet:
# Generate a not empty queryset
results_set = type(obj).objects.get_queryset().filter(project_id=obj.project.id)
compiler = results_set.query.get_compiler('default')
base_sql, base_params = compiler.as_sql(with_col_aliases=True)
query = """ query = """
SELECT * FROM SELECT * FROM
(SELECT "col1" as id, ROW_NUMBER() OVER() (SELECT "col1" as id,
ROW_NUMBER() OVER(),
LAG("col1", 1) OVER() AS prev,
LEAD("col1", 1) OVER() AS next
FROM (%s) as ID_AND_ROW) FROM (%s) as ID_AND_ROW)
AS SELECTED_ID_AND_ROW AS SELECTED_ID_AND_ROW
""" % (base_sql) """ % (base_sql)
@ -57,15 +70,17 @@ def get_neighbors(obj, results_set=None):
return Neighbor(None, None) return Neighbor(None, None)
obj_position = row[1] - 1 obj_position = row[1] - 1
left_object_id = row[2]
right_object_id = row[3]
try: try:
left = obj_position > 0 and results_set[obj_position - 1] or None left = results_set.get(id=left_object_id)
except IndexError: except ObjectDoesNotExist:
left = None left = None
try: try:
right = results_set[obj_position + 1] right = results_set.get(id=right_object_id)
except IndexError: except ObjectDoesNotExist:
right = None right = None
return Neighbor(left, right) return Neighbor(left, right)