django - 如果 django 表中不存在数据,如何引发错误消息
问题描述
我的表和过滤器都已设置并正常工作,但我希望添加一个错误功能,这样当我查询数据库中存在的数据时,它应该正常显示结果,但是,当我输入一个不存在的 qs,它应该在表格上显示一条消息,上面写着“记录不存在”而不是空白表格。
这是我的看法:
from django.contrib.auth.decorators import login_required
from django.contrib.auth.models import User
from django.shortcuts import render
from django_tables2 import RequestConfig
from django_tables2.export import TableExport
from .models import Employee
from .models import EmployeeFilter
from .tables import EmployeeTable
@login_required()
def employees(request):
filter = EmployeeFilter(request.GET, queryset=Employee.objects.all())
table = EmployeeTable(filter.qs)
RequestConfig(request).configure(table)
count = Employee.objects.all().count()
male_count = Employee.objects.filter(gender__contains='Male').count()
female_count = Employee.objects.filter(gender__contains='Female').count()
user_count = User.objects.all().count()
export_format = request.GET.get("_export", None)
if TableExport.is_valid_format(export_format):
exporter = TableExport(export_format, table)
return exporter.response("table.{}".format("csv", "xlsx"))
return render(request, "employees/employees.html", {
"table": table,
"filter": filter,
"count": count,
"male_count": male_count,
"female_count": female_count,
"user_count": user_count,
})
表格模板:
<!--filter form-->
<form action="" class="form form-inline employee-filter-form" method="get">
<legend class="mb-2">Filter employee records</legend>
<div class="fieldWrapper">
{{ filter.form.first_name }}
</div>
<div class="fieldWrapper">
{{ filter.form.last_name }}
</div>
<button aria-expanded="false" aria-haspopup="true"
class="ml-2 btn btn-danger filter-btn" type="submit">
Filter
</button>
</form>
解决方案
您可以在模板中处理它。只需检查您传递的查询集是否为空:
{% if queryset %}
{% for i in queryset %}
{{ i.text }}
{% endfor %}
{% else %}
Error: Queryset is empty!
{% endif %}
正如丹尼尔上面提到的,你也可以不用if
但用empty
:
{% for i in queryset %}
{{ i.text }}
{% empty %}
Error: Queryset is empty!
{% endfor %}