我需要使用传入的变量值重命名输出字段名称。有一个功能:
def metric_data(request, test_id, metric):
metric_name = metric
data = ServerMonitoringData.objects. \
filter(test_id=test_id). \
annotate(timestamp=RawSQL("((data->>%s)::timestamp)", ('timestamp',))).\
annotate(metric=RawSQL("((data->>%s)::numeric)", (metric,))). \
values('timestamp', "metric")
所以在这种情况下,无论变量指标带有什么值,输出看起来都像:
{"timestamp": "0:31:02", "metric": "8.82414500398"}
我需要一个键名等于公制变量的输出(如果公制=='CPU_iowait'):
{"timestamp": "0:31:02", "CPU_iowait": "8.82414500398"}
试图使用这样的东西:
metric_name = metric
...
annotate(metric_name=F('metric')).\
values('timestamp', metric_name)
但它存在'metric_name'时试图找到'CPU_iowait'列。那么有没有办法将字段名称作为变量传递?
# use dict to map the metric's name to a RawSQL query
# and pass it as keyword argument to `.annotate`.
metric_mapping = {
metric: RawSQL("((data->>%s)::numeric)", (metric,))
}
queryset.annotate(**metric_mapping)