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在* __ lte关键字中使用Django Q对象(Using Django Q objects in *__lte keywords)

我想在Django中这样做：

ThatModel.objects.filter(desired_moisture__lte=Q( F("sensor__moisture") + F("sensor__calibrate_low")) / F("sensor__calibrate_high") + F("upper_deviation"))

这是一种有代表性的，所以这就是我试图以一种不那么罗嗦的方式做的事情：

a <= (b + c) / d + e

但是，这会导致：

[2014-06-10 00:17:22,724: ERROR/MainProcess] Task pidrator.hardware_controller.CheckIrrigators[67c82981-780e-4c39-b88c-08a728773dd1] raised unexpected: IntegrityError("Failed processing format-parameters; Python 'q' cannot be converted to a MySQL type",) Traceback (most recent call last): File "/usr/lib/python3.4/site-packages/celery/app/trace.py", line 240, in trace_task R = retval = fun(*args, **kwargs) File "/usr/lib/python3.4/site-packages/celery/app/trace.py", line 437, in __protected_call__ return self.run(*args, **kwargs) File "/home/max/programming/pidrator/pidrator/hardware_controller.py", line 93, in CheckIrrigators **filter_args): File "/usr/lib/python3.4/site-packages/django/db/models/query.py", line 96, in __iter__ self._fetch_all() File "/usr/lib/python3.4/site-packages/django/db/models/query.py", line 857, in _fetch_all self._result_cache = list(self.iterator()) File "/usr/lib/python3.4/site-packages/django/db/models/query.py", line 220, in iterator for row in compiler.results_iter(): File "/usr/lib/python3.4/site-packages/django/db/models/sql/compiler.py", line 713, in results_iter for rows in self.execute_sql(MULTI): File "/usr/lib/python3.4/site-packages/django/db/models/sql/compiler.py", line 786, in execute_sql cursor.execute(sql, params) File "/usr/lib/python3.4/site-packages/django/db/backends/util.py", line 53, in execute return self.cursor.execute(sql, params) File "/usr/lib/python3.4/site-packages/mysql/connector/django/base.py", line 117, in execute return self._execute_wrapper(self.cursor.execute, query, args) File "/usr/lib/python3.4/site-packages/mysql/connector/django/base.py", line 103, in _execute_wrapper utils.IntegrityError(err.msg), sys.exc_info()[2]) File "/usr/lib/python3.4/site-packages/django/utils/six.py", line 549, in reraise raise value.with_traceback(tb) File "/usr/lib/python3.4/site-packages/mysql/connector/django/base.py", line 99, in _execute_wrapper return method(query, args) File "/usr/lib/python3.4/site-packages/mysql/connector/cursor.py", line 502, in execute psub = _ParamSubstitutor(self._process_params(params)) File "/usr/lib/python3.4/site-packages/mysql/connector/cursor.py", line 378, in _process_params "Failed processing format-parameters; %s" % err) django.db.utils.IntegrityError: Failed processing format-parameters; Python 'q' cannot be converted to a MySQL type

desired_moisture__lte似乎无法处理我传递给它的Q对象。 我该如何工作？

I am trying to do this in Django:

ThatModel.objects.filter(desired_moisture__lte=Q( F("sensor__moisture") + F("sensor__calibrate_low")) / F("sensor__calibrate_high") + F("upper_deviation"))

This is kind of a codeful, so here's what I'm trying to do in a less-wordy way:

a <= (b + c) / d + e

However, this results in this:

[2014-06-10 00:17:22,724: ERROR/MainProcess] Task pidrator.hardware_controller.CheckIrrigators[67c82981-780e-4c39-b88c-08a728773dd1] raised unexpected: IntegrityError("Failed processing format-parameters; Python 'q' cannot be converted to a MySQL type",) Traceback (most recent call last): File "/usr/lib/python3.4/site-packages/celery/app/trace.py", line 240, in trace_task R = retval = fun(*args, **kwargs) File "/usr/lib/python3.4/site-packages/celery/app/trace.py", line 437, in __protected_call__ return self.run(*args, **kwargs) File "/home/max/programming/pidrator/pidrator/hardware_controller.py", line 93, in CheckIrrigators **filter_args): File "/usr/lib/python3.4/site-packages/django/db/models/query.py", line 96, in __iter__ self._fetch_all() File "/usr/lib/python3.4/site-packages/django/db/models/query.py", line 857, in _fetch_all self._result_cache = list(self.iterator()) File "/usr/lib/python3.4/site-packages/django/db/models/query.py", line 220, in iterator for row in compiler.results_iter(): File "/usr/lib/python3.4/site-packages/django/db/models/sql/compiler.py", line 713, in results_iter for rows in self.execute_sql(MULTI): File "/usr/lib/python3.4/site-packages/django/db/models/sql/compiler.py", line 786, in execute_sql cursor.execute(sql, params) File "/usr/lib/python3.4/site-packages/django/db/backends/util.py", line 53, in execute return self.cursor.execute(sql, params) File "/usr/lib/python3.4/site-packages/mysql/connector/django/base.py", line 117, in execute return self._execute_wrapper(self.cursor.execute, query, args) File "/usr/lib/python3.4/site-packages/mysql/connector/django/base.py", line 103, in _execute_wrapper utils.IntegrityError(err.msg), sys.exc_info()[2]) File "/usr/lib/python3.4/site-packages/django/utils/six.py", line 549, in reraise raise value.with_traceback(tb) File "/usr/lib/python3.4/site-packages/mysql/connector/django/base.py", line 99, in _execute_wrapper return method(query, args) File "/usr/lib/python3.4/site-packages/mysql/connector/cursor.py", line 502, in execute psub = _ParamSubstitutor(self._process_params(params)) File "/usr/lib/python3.4/site-packages/mysql/connector/cursor.py", line 378, in _process_params "Failed processing format-parameters; %s" % err) django.db.utils.IntegrityError: Failed processing format-parameters; Python 'q' cannot be converted to a MySQL type

desired_moisture__lte seems to be unable to handle the Q object I'm passing to it. How do I make this work?

最满意答案

摆脱包裹Q() ，你应该有一个工作结果。 有关示例，请参阅https://docs.djangoproject.com/en/dev/topics/db/queries/#using-f-expressions-in-filters 。

ThatModel.objects.filter(desired_moisture__lte=(F("sensor__moisture") + F("sensor__calibrate_low")) / F("sensor__calibrate_high") + F("upper_deviation"))

Get rid of the wrapping Q() and you should have a working result. See https://docs.djangoproject.com/en/dev/topics/db/queries/#using-f-expressions-in-filters for examples.

ThatModel.objects.filter(desired_moisture__lte=(F("sensor__moisture") + F("sensor__calibrate_low")) / F("sensor__calibrate_high") + F("upper_deviation"))