系统:Windows 7 语言版本:Anaconda3-4.3.0.1-Windows-x86_64 编辑器:pycharm-community-2016.3.2 Django:2.1.4 Python:3.6.0
Part 1:目标
Part 2:数据库操作 - 查询某列全部信息
Constants.objects.values_list('class_name')
,获取常数项表中class_name字段的所有数据,其中Constants类内容如下['三年1班', '三年2班', '三年3班', None, None, None, None, None, None]
while None in list_class_name:
list_class_name.remove(None)
数据库class_name 字段
查询结果
Constants类
class Constants(models.Model):
class_name = models.CharField(blank=True, null=True, max_length=10, verbose_name='班级')
student_name = models.CharField(blank=True, null=True, max_length=10, verbose_name='学生姓名')
exam_info = models.CharField(blank=True, null=True, max_length=20, verbose_name='模拟考信息')
course_name = models.CharField(blank=True, null=True, max_length=20, verbose_name='科目')
class Meta:
db_table = 'grades_constants'
verbose_name = "常数项"
verbose_name_plural = verbose_name
Part 3:查询方式优化
class_name = Constants.objects.values_list('class_name')
list_class_name = [x[0] for x in list(class_name)]
while None in list_class_name:
list_class_name.remove(None)
list_all_class_name = list(set(list_class_name))
list_all_class_name.sort()
Constants.objects.values_list('class_name')
是支持传入多个字段名称的def constants_sort(list_input):
while None in list_input:
list_input.remove(None)
list_all = list(set(list_input))
list_all.sort()
return list_all
class SGInputAndCheckView(View):
def get(self, request):
list_field_name = ['class_name', 'student_name', 'exam_info', 'course_name']
constants_list = Constants.objects.values_list(*list_field_name)
print(constants_list)
list_class_name = [x[0] for x in list(constants_list)]
list_student_name = [x[1] for x in list(constants_list)]
list_exam_info = [x[0] for x in list(constants_list)]
list_course_name = [x[0] for x in list(constants_list)]
list_all_class_name = constants_sort(list_class_name)
list_all_student_name = constants_sort(list_student_name)
list_all_exam_info = constants_sort(list_exam_info)
list_all_course_name = constants_sort(list_course_name)
return render(request, 'sg_first_page.html', {
'all_class_name': list_all_class_name,
'all_student_name': list_all_student_name,
'all_exam_info': list_all_exam_info,
'all_course_name': list_all_course_name,
})
constants_list
*list_field_name
是一种将列表转化为一个个单独的元素的方法,如以下示例
以上为本次的学习内容,下回见