Django:查询集对象过滤器,针对另一个对象的时间范围
Django: Queryset object filter, against another object's time range
我有3个模型,运行,sensor_parameter和data。它们之间还有其他外键关系,但是 运行 没有直接外键到 sensor_parameter 或 数据.
A 运行 有一个 start_time 和一个 end_time ,并且与 chamber.
有关
class Run(models.Model):
start_time = models.DateTimeField(db_index=True)
end_time = models.DateTimeField(db_index=True)
chamber = models.ForeignKey(Chamber, on_delete=models.CASCADE)
A chamber 与 sensor 有关系,而 sensor 有一组sensor_parameter(s)
class SensorParameter(models.Model):
sensor = models.ForeignKey(Sensor)
parameter = models.ForeignKey(Parameter)
最后 data 指向 "belongs" 到 sensor_parameter:
class Data(models.Model):
time = models.DateTimeField(db_index=True)
sensor_parameter = models.ForeignKey(SensorParameter, on_delete=models.CASCADE)
parameter_value = models.FloatField()
我需要过滤属于 运行 的 sensor_parameter(s) 列表,但我在他们之间的唯一 link 是一个时间值。由于 data 有时间戳,而 运行 有 start_time和end_time,我想我可以过滤一个时间段范围内data.sensor_parameter的列表。
我不确定如何构建查询集过滤器。
我已经导入了日期时间,并且可以访问 django_filter。
这是我目前的 views.py
import datetime
import django_filters
def get(self, request):
# Get a list of run objects, that are passed through the request
run_ids = request.GET.getlist('id')
runs = Run.objects.filter(pk__in=run_ids)
# Get a list of all chambers that own those runs
chamber = Chamber.objects.filter(run__in=runs).distinct()
# Get a list of all sensors that belong to those chambers
sensor = Sensor.objects.filter(chamber=chamber)
# Looking around, I saw these two DateTimeFilter expressions from django_filters
time__gte = django_filters.DateTimeFilter(name="time", lookup_expr='gte')
time__lte = django_filters.DateTimeFilter(name="time", lookup_expr='lte')
# Here I would have to determine which run.start_time is lower
# And which run.end_time is higher, to get a valid time range
# This part is not finished yet
time_start = run.start_time
time_end = run.end_time
# This is the filter I'm having trouble implementing
sensor_parameters = SensorParameter.objects.filter(sensor=sensor, data__time__gte=time_start, data__time__lte=time_end)
return render(request, self.template_name, {'run': run, 'sensor_parameters': sensor_parameters})
基本上,我想如果我从我的 运行s(它可以不止一个 运行,我必须确定哪个 start_time 较低,哪个 end_time 更大),然后我可以使用时间范围过滤 sensor_parameter 对 data.time .
我不知道如何从这里开始。
此外,如果有任何不同,我们会使用 PostgreSQL。
如果你看到任何明显的错误或语法错误,请随时纠正和批评,我仍然是一个新手,无论是 Django 还是 Python,但喜欢它的每一分钟。
我自己设法做到了,尽管我不确定我这样做的方式是否是最好的方式。我将保持上面的代码不变,以演示问题出在哪里,并提供与我实现的解决方案的比较点。
日期范围的想法是正确的,因为 data.time 是我唯一的 link 到 run.start_time - run.end_time.
所以我通过添加所有 run.start_time 和 [= 来确定 range_period 39=] 到几个列表,然后我调用这些列表上的 min() 和 max() 方法来提取所需的时间段,然后将其放入列表中,这是(包含的)__range 过滤器需要作为输入的内容。
为了清楚起见,下面是 views.py 注释:
class ChartRunsView(generic.DetailView):
model = Run
template_name = 'chart_runs.html'
def get(self, request):
# Get a list of run objects, that are passed through the request
run_ids = request.GET.getlist('id')
runs = Run.objects.filter(pk__in=run_ids)
# Get a list of all chambers that own those runs
chamber = Chamber.objects.filter(run__in=runs).distinct()
# Get a list of all sensors that belong to those chambers
sensor = Sensor.objects.filter(chamber=chamber)
# Initialize run_start and run_end lists
run_start_list = []
run_end_list = []
# Append start_time(s) and end_time(s) for all runs
for run in runs:
run_start_list.append(run.start_time)
run_end_list.append(run.end_time)
# Determine the earliest and latest time stamps for all the extracted run times
# Using Python's min() and max() list methods
runs_start = min(run_start_list)
runs_end = max(run_end_list)
# Build a new list with the earliest run_start and latest run_end
range_period = [runs_start, runs_end]
# Build query that will filter all SensorParameter objects against sensor, and data
# Using the __range filter method, which takes a list as input.
# This will return all SensorParameter objects in that time range, which could potentially
# be thousands. Applying the .distinct() filter method on the resulting queryset gives us
# only unique results
sensor_parameters = SensorParameter.objects.filter(sensor__in=sensor, data__time__range=range_period).distinct()
return render(request, self.template_name, {'runs': runs,
'sensor_parameters': sensor_parameters})
我有3个模型,运行,sensor_parameter和data。它们之间还有其他外键关系,但是 运行 没有直接外键到 sensor_parameter 或 数据.
A 运行 有一个 start_time 和一个 end_time ,并且与 chamber.
有关class Run(models.Model):
start_time = models.DateTimeField(db_index=True)
end_time = models.DateTimeField(db_index=True)
chamber = models.ForeignKey(Chamber, on_delete=models.CASCADE)
A chamber 与 sensor 有关系,而 sensor 有一组sensor_parameter(s)
class SensorParameter(models.Model):
sensor = models.ForeignKey(Sensor)
parameter = models.ForeignKey(Parameter)
最后 data 指向 "belongs" 到 sensor_parameter:
class Data(models.Model):
time = models.DateTimeField(db_index=True)
sensor_parameter = models.ForeignKey(SensorParameter, on_delete=models.CASCADE)
parameter_value = models.FloatField()
我需要过滤属于 运行 的 sensor_parameter(s) 列表,但我在他们之间的唯一 link 是一个时间值。由于 data 有时间戳,而 运行 有 start_time和end_time,我想我可以过滤一个时间段范围内data.sensor_parameter的列表。
我不确定如何构建查询集过滤器。
我已经导入了日期时间,并且可以访问 django_filter。
这是我目前的 views.py
import datetime
import django_filters
def get(self, request):
# Get a list of run objects, that are passed through the request
run_ids = request.GET.getlist('id')
runs = Run.objects.filter(pk__in=run_ids)
# Get a list of all chambers that own those runs
chamber = Chamber.objects.filter(run__in=runs).distinct()
# Get a list of all sensors that belong to those chambers
sensor = Sensor.objects.filter(chamber=chamber)
# Looking around, I saw these two DateTimeFilter expressions from django_filters
time__gte = django_filters.DateTimeFilter(name="time", lookup_expr='gte')
time__lte = django_filters.DateTimeFilter(name="time", lookup_expr='lte')
# Here I would have to determine which run.start_time is lower
# And which run.end_time is higher, to get a valid time range
# This part is not finished yet
time_start = run.start_time
time_end = run.end_time
# This is the filter I'm having trouble implementing
sensor_parameters = SensorParameter.objects.filter(sensor=sensor, data__time__gte=time_start, data__time__lte=time_end)
return render(request, self.template_name, {'run': run, 'sensor_parameters': sensor_parameters})
基本上,我想如果我从我的 运行s(它可以不止一个 运行,我必须确定哪个 start_time 较低,哪个 end_time 更大),然后我可以使用时间范围过滤 sensor_parameter 对 data.time .
我不知道如何从这里开始。
此外,如果有任何不同,我们会使用 PostgreSQL。
如果你看到任何明显的错误或语法错误,请随时纠正和批评,我仍然是一个新手,无论是 Django 还是 Python,但喜欢它的每一分钟。
我自己设法做到了,尽管我不确定我这样做的方式是否是最好的方式。我将保持上面的代码不变,以演示问题出在哪里,并提供与我实现的解决方案的比较点。
日期范围的想法是正确的,因为 data.time 是我唯一的 link 到 run.start_time - run.end_time.
所以我通过添加所有 run.start_time 和 [= 来确定 range_period 39=] 到几个列表,然后我调用这些列表上的 min() 和 max() 方法来提取所需的时间段,然后将其放入列表中,这是(包含的)__range 过滤器需要作为输入的内容。
为了清楚起见,下面是 views.py 注释:
class ChartRunsView(generic.DetailView):
model = Run
template_name = 'chart_runs.html'
def get(self, request):
# Get a list of run objects, that are passed through the request
run_ids = request.GET.getlist('id')
runs = Run.objects.filter(pk__in=run_ids)
# Get a list of all chambers that own those runs
chamber = Chamber.objects.filter(run__in=runs).distinct()
# Get a list of all sensors that belong to those chambers
sensor = Sensor.objects.filter(chamber=chamber)
# Initialize run_start and run_end lists
run_start_list = []
run_end_list = []
# Append start_time(s) and end_time(s) for all runs
for run in runs:
run_start_list.append(run.start_time)
run_end_list.append(run.end_time)
# Determine the earliest and latest time stamps for all the extracted run times
# Using Python's min() and max() list methods
runs_start = min(run_start_list)
runs_end = max(run_end_list)
# Build a new list with the earliest run_start and latest run_end
range_period = [runs_start, runs_end]
# Build query that will filter all SensorParameter objects against sensor, and data
# Using the __range filter method, which takes a list as input.
# This will return all SensorParameter objects in that time range, which could potentially
# be thousands. Applying the .distinct() filter method on the resulting queryset gives us
# only unique results
sensor_parameters = SensorParameter.objects.filter(sensor__in=sensor, data__time__range=range_period).distinct()
return render(request, self.template_name, {'runs': runs,
'sensor_parameters': sensor_parameters})