通过 Django ORM 创建案例查询
Create Case query via Django ORM
使用 Django 1.8 和 Postgres 9.3 - 我有一个 Django 模型，如下所示，其中包含日志行。我想提取所有 domain_name 从未被允许访问的值。
class Logs(models.Model):
date = DateTimeField(db_index=True)
action = TextField(default='a', null=True, blank=True, db_index=True)
url = TextField(null=True, blank=True)
stats = JsonField(null=True, blank=True)
domain_name = TextField(null=True, blank=True, db_index=True)
<snip>
这个 SQL 查询工作得很好，但我在将它转换为 Django ORM 查询集时遇到了问题。
select domain_name from reporter_log
GROUP BY domain_name
HAVING COUNT(CASE WHEN action = 'a' OR action = 'ae' then 1 END) = 0;
我原以为以下查询集会起作用：
LogLine.objects.annotate(
allowed=Count(Case(
When(action='a', then=Value(1)),
When(action='ae', then=Value(1)),
default=Value(0),
output_field=IntegerField(),
)
))
但我得到了回溯：
ProgrammingError Traceback (most recent call last)
<ipython-input-4-feb056328fe8> in <module>()
4 When(action='ae', then=Value(1)),
5 default=Value(0),
----> 6 output_field=IntegerField(),
7 )
8 ))
/usr/lib/python3/dist-packages/IPython/core/displayhook.py in __call__(self, result)
245 self.start_displayhook()
246 self.write_output_prompt()
--> 247 format_dict, md_dict = self.compute_format_data(result)
248 self.write_format_data(format_dict, md_dict)
249 self.update_user_ns(result)
/usr/lib/python3/dist-packages/IPython/core/displayhook.py in compute_format_data(self, result)
155
156 """
--> 157 return self.shell.display_formatter.format(result)
158
159 def write_format_data(self, format_dict, md_dict=None):
/usr/lib/python3/dist-packages/IPython/core/formatters.py in format(self, obj, include, exclude)
150 md = None
151 try:
--> 152 data = formatter(obj)
153 except:
154 # FIXME: log the exception
/usr/lib/python3/dist-packages/IPython/core/formatters.py in __call__(self, obj)
478 type_pprinters=self.type_printers,
479 deferred_pprinters=self.deferred_printers)
--> 480 printer.pretty(obj)
481 printer.flush()
482 return stream.getvalue()
/usr/lib/python3/dist-packages/IPython/lib/pretty.py in pretty(self, obj)
361 if isinstance(meth, collections.Callable):
362 return meth(obj, self, cycle)
--> 363 return _default_pprint(obj, self, cycle)
364 finally:
365 self.end_group()
/usr/lib/python3/dist-packages/IPython/lib/pretty.py in _default_pprint(obj, p, cycle)
481 if getattr(klass, '__repr__', None) not in _baseclass_reprs:
482 # A user-provided repr.
--> 483 p.text(repr(obj))
484 return
485 p.begin_group(1, '<')
/usr/local/lib/python3.4/dist-packages/django/db/models/query.py in __repr__(self)
136
137 def __repr__(self):
--> 138 data = list(self[:REPR_OUTPUT_SIZE + 1])
139 if len(data) > REPR_OUTPUT_SIZE:
140 data[-1] = "...(remaining elements truncated)..."
/usr/local/lib/python3.4/dist-packages/django/db/models/query.py in __iter__(self)
160 - Responsible for turning the rows into model objects.
161 """
--> 162 self._fetch_all()
163 return iter(self._result_cache)
164
/usr/local/lib/python3.4/dist-packages/django/db/models/query.py in _fetch_all(self)
963 def _fetch_all(self):
964 if self._result_cache is None:
--> 965 self._result_cache = list(self.iterator())
966 if self._prefetch_related_lookups and not self._prefetch_done:
967 self._prefetch_related_objects()
/usr/local/lib/python3.4/dist-packages/django/db/models/query.py in iterator(self)
236 # Execute the query. This will also fill compiler.select, klass_info,
237 # and annotations.
--> 238 results = compiler.execute_sql()
239 select, klass_info, annotation_col_map = (compiler.select, compiler.klass_info,
240 compiler.annotation_col_map)
/usr/local/lib/python3.4/dist-packages/django/db/models/sql/compiler.py in execute_sql(self, result_type)
838 cursor = self.connection.cursor()
839 try:
--> 840 cursor.execute(sql, params)
841 except Exception:
842 cursor.close()
/usr/local/lib/python3.4/dist-packages/django/db/backends/utils.py in execute(self, sql, params)
77 start = time()
78 try:
---> 79 return super(CursorDebugWrapper, self).execute(sql, params)
80 finally:
81 stop = time()
/usr/local/lib/python3.4/dist-packages/django/db/backends/utils.py in execute(self, sql, params)
62 return self.cursor.execute(sql)
63 else:
---> 64 return self.cursor.execute(sql, params)
65
66 def executemany(self, sql, param_list):
/usr/local/lib/python3.4/dist-packages/django/db/utils.py in __exit__(self, exc_type, exc_value, traceback)
95 if dj_exc_type not in (DataError, IntegrityError):
96 self.wrapper.errors_occurred = True
---> 97 six.reraise(dj_exc_type, dj_exc_value, traceback)
98
99 def __call__(self, func):
/usr/local/lib/python3.4/dist-packages/django/utils/six.py in reraise(tp, value, tb)
656 value = tp()
657 if value.__traceback__ is not tb:
--> 658 raise value.with_traceback(tb)
659 raise value
660
/usr/local/lib/python3.4/dist-packages/django/db/backends/utils.py in execute(self, sql, params)
62 return self.cursor.execute(sql)
63 else:
---> 64 return self.cursor.execute(sql, params)
65
66 def executemany(self, sql, param_list):
ProgrammingError: could not identify an equality operator for type json
LINE 1: ...e"."domain_name", "reporter_logs"."rule_type", "reporter_...
^
这是查询失败的输出。
[{'sql': 'SELECT "reporter_logs"."id", "reporter_logs"."date", "reporter_logs"."userip", "reporter_logs"."action", "reporter_logs"."url", "reporter_logs"."method", "reporter_logs"."status", "reporter_logs"."mimetype", "reporter_logs"."content_length", "reporter_logs"."pruned", "reporter_logs"."page_title", "reporter_logs"."user_agent", "reporter_logs"."domain_name", "reporter_logs"."rule_type", "reporter_logs"."tally_stats", "reporter_logs"."cat_stats", "reporter_logs"."grade_stats", "reporter_logs"."ignored", "reporter_logs"."category", "reporter_logs"."genre", "reporter_logs"."grade", "reporter_logs"."top_grade", "reporter_logs"."category_confidence", "reporter_logs"."grade_confidence", COUNT(CASE WHEN "reporter_logs"."action" = \'a\' THEN 1 WHEN "reporter_logs"."action" = \'ae\' THEN 1 ELSE 0 END) AS "allowed" FROM "reporter_logs" GROUP BY "reporter_logs"."id", "reporter_logs"."date", "reporter_logs"."userip", "reporter_logs"."action", "reporter_logs"."url", "reporter_logs"."method", "reporter_logs"."status", "reporter_logs"."mimetype", "reporter_logs"."content_length", "reporter_logs"."pruned", "reporter_logs"."page_title", "reporter_logs"."user_agent", "reporter_logs"."domain_name", "reporter_logs"."rule_type", "reporter_logs"."tally_stats", "reporter_logs"."cat_stats", "reporter_logs"."grade_stats", "reporter_logs"."ignored", "reporter_logs"."category", "reporter_logs"."genre", "reporter_logs"."grade", "reporter_logs"."top_grade", "reporter_logs"."category_confidence", "reporter_logs"."grade_confidence" LIMIT 21', 'time': '0.002'}]
如有任何建议，我们将不胜感激。包括有关编写查询的替代方法的建议。
尝试不使用 Q 函数，使用分隔的 When 代替：
Logs.objects.annotate(
allowed=Count(Case(
When(action='a', then=1),
When(action='ae', then=1),
default=0,
output_field=IntegerField()
)
)).values('date')
嗯，感谢@knbk 和@Gocht 的尝试。我终于找到了解决问题的方法。我必须指定我只想要 domain_name 列，它负责回溯。
此外，对于所有没有匹配项的域，我不得不使用 Sum 而不是 Count 来 return 0。计数 returned 1 不匹配的值。
Logs.objects.values('domain_name').annotate(
allowed=Sum(Case(
When(Q(action='a') |Q(action='ae'), then=Value(1)),
default=Value(0),
output_field=IntegerField()
)
))
使用 Django 1.8 和 Postgres 9.3 - 我有一个 Django 模型，如下所示，其中包含日志行。我想提取所有 domain_name 从未被允许访问的值。
class Logs(models.Model):
date = DateTimeField(db_index=True)
action = TextField(default='a', null=True, blank=True, db_index=True)
url = TextField(null=True, blank=True)
stats = JsonField(null=True, blank=True)
domain_name = TextField(null=True, blank=True, db_index=True)
<snip>
这个 SQL 查询工作得很好，但我在将它转换为 Django ORM 查询集时遇到了问题。
select domain_name from reporter_log
GROUP BY domain_name
HAVING COUNT(CASE WHEN action = 'a' OR action = 'ae' then 1 END) = 0;
我原以为以下查询集会起作用：
LogLine.objects.annotate(
allowed=Count(Case(
When(action='a', then=Value(1)),
When(action='ae', then=Value(1)),
default=Value(0),
output_field=IntegerField(),
)
))
但我得到了回溯：
ProgrammingError Traceback (most recent call last)
<ipython-input-4-feb056328fe8> in <module>()
4 When(action='ae', then=Value(1)),
5 default=Value(0),
----> 6 output_field=IntegerField(),
7 )
8 ))
/usr/lib/python3/dist-packages/IPython/core/displayhook.py in __call__(self, result)
245 self.start_displayhook()
246 self.write_output_prompt()
--> 247 format_dict, md_dict = self.compute_format_data(result)
248 self.write_format_data(format_dict, md_dict)
249 self.update_user_ns(result)
/usr/lib/python3/dist-packages/IPython/core/displayhook.py in compute_format_data(self, result)
155
156 """
--> 157 return self.shell.display_formatter.format(result)
158
159 def write_format_data(self, format_dict, md_dict=None):
/usr/lib/python3/dist-packages/IPython/core/formatters.py in format(self, obj, include, exclude)
150 md = None
151 try:
--> 152 data = formatter(obj)
153 except:
154 # FIXME: log the exception
/usr/lib/python3/dist-packages/IPython/core/formatters.py in __call__(self, obj)
478 type_pprinters=self.type_printers,
479 deferred_pprinters=self.deferred_printers)
--> 480 printer.pretty(obj)
481 printer.flush()
482 return stream.getvalue()
/usr/lib/python3/dist-packages/IPython/lib/pretty.py in pretty(self, obj)
361 if isinstance(meth, collections.Callable):
362 return meth(obj, self, cycle)
--> 363 return _default_pprint(obj, self, cycle)
364 finally:
365 self.end_group()
/usr/lib/python3/dist-packages/IPython/lib/pretty.py in _default_pprint(obj, p, cycle)
481 if getattr(klass, '__repr__', None) not in _baseclass_reprs:
482 # A user-provided repr.
--> 483 p.text(repr(obj))
484 return
485 p.begin_group(1, '<')
/usr/local/lib/python3.4/dist-packages/django/db/models/query.py in __repr__(self)
136
137 def __repr__(self):
--> 138 data = list(self[:REPR_OUTPUT_SIZE + 1])
139 if len(data) > REPR_OUTPUT_SIZE:
140 data[-1] = "...(remaining elements truncated)..."
/usr/local/lib/python3.4/dist-packages/django/db/models/query.py in __iter__(self)
160 - Responsible for turning the rows into model objects.
161 """
--> 162 self._fetch_all()
163 return iter(self._result_cache)
164
/usr/local/lib/python3.4/dist-packages/django/db/models/query.py in _fetch_all(self)
963 def _fetch_all(self):
964 if self._result_cache is None:
--> 965 self._result_cache = list(self.iterator())
966 if self._prefetch_related_lookups and not self._prefetch_done:
967 self._prefetch_related_objects()
/usr/local/lib/python3.4/dist-packages/django/db/models/query.py in iterator(self)
236 # Execute the query. This will also fill compiler.select, klass_info,
237 # and annotations.
--> 238 results = compiler.execute_sql()
239 select, klass_info, annotation_col_map = (compiler.select, compiler.klass_info,
240 compiler.annotation_col_map)
/usr/local/lib/python3.4/dist-packages/django/db/models/sql/compiler.py in execute_sql(self, result_type)
838 cursor = self.connection.cursor()
839 try:
--> 840 cursor.execute(sql, params)
841 except Exception:
842 cursor.close()
/usr/local/lib/python3.4/dist-packages/django/db/backends/utils.py in execute(self, sql, params)
77 start = time()
78 try:
---> 79 return super(CursorDebugWrapper, self).execute(sql, params)
80 finally:
81 stop = time()
/usr/local/lib/python3.4/dist-packages/django/db/backends/utils.py in execute(self, sql, params)
62 return self.cursor.execute(sql)
63 else:
---> 64 return self.cursor.execute(sql, params)
65
66 def executemany(self, sql, param_list):
/usr/local/lib/python3.4/dist-packages/django/db/utils.py in __exit__(self, exc_type, exc_value, traceback)
95 if dj_exc_type not in (DataError, IntegrityError):
96 self.wrapper.errors_occurred = True
---> 97 six.reraise(dj_exc_type, dj_exc_value, traceback)
98
99 def __call__(self, func):
/usr/local/lib/python3.4/dist-packages/django/utils/six.py in reraise(tp, value, tb)
656 value = tp()
657 if value.__traceback__ is not tb:
--> 658 raise value.with_traceback(tb)
659 raise value
660
/usr/local/lib/python3.4/dist-packages/django/db/backends/utils.py in execute(self, sql, params)
62 return self.cursor.execute(sql)
63 else:
---> 64 return self.cursor.execute(sql, params)
65
66 def executemany(self, sql, param_list):
ProgrammingError: could not identify an equality operator for type json
LINE 1: ...e"."domain_name", "reporter_logs"."rule_type", "reporter_...
^
这是查询失败的输出。
[{'sql': 'SELECT "reporter_logs"."id", "reporter_logs"."date", "reporter_logs"."userip", "reporter_logs"."action", "reporter_logs"."url", "reporter_logs"."method", "reporter_logs"."status", "reporter_logs"."mimetype", "reporter_logs"."content_length", "reporter_logs"."pruned", "reporter_logs"."page_title", "reporter_logs"."user_agent", "reporter_logs"."domain_name", "reporter_logs"."rule_type", "reporter_logs"."tally_stats", "reporter_logs"."cat_stats", "reporter_logs"."grade_stats", "reporter_logs"."ignored", "reporter_logs"."category", "reporter_logs"."genre", "reporter_logs"."grade", "reporter_logs"."top_grade", "reporter_logs"."category_confidence", "reporter_logs"."grade_confidence", COUNT(CASE WHEN "reporter_logs"."action" = \'a\' THEN 1 WHEN "reporter_logs"."action" = \'ae\' THEN 1 ELSE 0 END) AS "allowed" FROM "reporter_logs" GROUP BY "reporter_logs"."id", "reporter_logs"."date", "reporter_logs"."userip", "reporter_logs"."action", "reporter_logs"."url", "reporter_logs"."method", "reporter_logs"."status", "reporter_logs"."mimetype", "reporter_logs"."content_length", "reporter_logs"."pruned", "reporter_logs"."page_title", "reporter_logs"."user_agent", "reporter_logs"."domain_name", "reporter_logs"."rule_type", "reporter_logs"."tally_stats", "reporter_logs"."cat_stats", "reporter_logs"."grade_stats", "reporter_logs"."ignored", "reporter_logs"."category", "reporter_logs"."genre", "reporter_logs"."grade", "reporter_logs"."top_grade", "reporter_logs"."category_confidence", "reporter_logs"."grade_confidence" LIMIT 21', 'time': '0.002'}]
如有任何建议，我们将不胜感激。包括有关编写查询的替代方法的建议。
尝试不使用 Q 函数，使用分隔的 When 代替：
Logs.objects.annotate(
allowed=Count(Case(
When(action='a', then=1),
When(action='ae', then=1),
default=0,
output_field=IntegerField()
)
)).values('date')
嗯，感谢@knbk 和@Gocht 的尝试。我终于找到了解决问题的方法。我必须指定我只想要 domain_name 列，它负责回溯。
此外，对于所有没有匹配项的域，我不得不使用 Sum 而不是 Count 来 return 0。计数 returned 1 不匹配的值。
Logs.objects.values('domain_name').annotate(
allowed=Sum(Case(
When(Q(action='a') |Q(action='ae'), then=Value(1)),
default=Value(0),
output_field=IntegerField()
)
))