Django Admin出现异常时如何重试？

Question

如果发生异常，我想重试Django 管理员:

1. 尝试添加数据时：
   2. 尝试更改数据时：
   3. 点击时删除在“更改”页面:

   然后点击是，我确定尝试删除数据：

   4. 点击时走在“选择更改”页面:

   然后点击是，我确定尝试删除数据：

   我有Person模特以下：

   # "store/models.py"
   
   from django.db import models
   
   class Person(models.Model):
       name = models.CharField(max_length=30)
   

   和，Person管理员以下：

   # "store/admin.py"
   
   from django.contrib import admin
   from .models import Person
   
   @admin.register(Person)
   class PersonAdmin(admin.ModelAdmin):
       pass
   

   那么，当发生异常时我该如何重试Django 管理员？

Answer 1

您可以使用下面的retry()重试Django 管理员0 次或更多次，间隔秒数为 0 或更多：

# "store/admin.py"

from django.db import DatabaseError, IntegrityError, transaction, router
from django.contrib import messages, admin
from django.shortcuts import redirect
from time import sleep
from .models import Person
from django.utils.decorators import method_decorator
from django.views.decorators.csrf import csrf_protect
csrf_protect_m = method_decorator(csrf_protect)

def retry(count, interval=1):
    def _retry(func):
        def core(*args, **kwargs):
            nonlocal count
            if callable(count):
                count = 2
            for i in range(count+1):
                try:
                    return func(*args, **kwargs)
                except DatabaseError as e:
                    print(e)
                    if i == count:
                        messages.error(args[1], "Error occurred, try again!")
                        return redirect("/".join(args[1].path.split('/')[0:4]))
                    sleep(interval)
        return core
    
    if callable(count):
        return _retry(count)
    return _retry

# ...

然后，使用@retry(4, 2)被覆盖的changeform_view()除了每次异常发生时正常尝试之外，还可以重试添加和更改数据 4 次，间隔为 2 秒，如下所示：

# "store/admin.py"

from django.db import DatabaseError, IntegrityError, transaction, router
from django.contrib import messages, admin
from django.shortcuts import redirect
from time import sleep
from .models import Person
from django.utils.decorators import method_decorator
from django.views.decorators.csrf import csrf_protect
csrf_protect_m = method_decorator(csrf_protect)

def retry(count, interval=1):
    # ...

@admin.register(Person)
class PersonAdmin(admin.ModelAdmin):

    @retry(4, 2) # Here
    @csrf_protect_m
    def changeform_view(self, request, object_id=None, form_url="", extra_context=None):
        with transaction.atomic(using=router.db_for_write(self.model)):
            return self._changeform_view(request, object_id, form_url, extra_context)

所以，让我们提出IntegrityError异常在覆盖的response_add()和response_change()如下所示：

# ...

@admin.register(Person)
class PersonAdmin(admin.ModelAdmin):

    @retry(4, 2) # Here
    @csrf_protect_m
    def changeform_view(self, request, object_id=None, form_url="", extra_context=None):
        with transaction.atomic(using=router.db_for_write(self.model)):
            return super()._changeform_view(request, object_id, form_url, extra_context)

    def response_add(self, request, obj, post_url_continue=None):
        raise IntegrityError("Exception occurs") # Here
        return super().response_add(request, obj, post_url_continue)

    def response_change(self, request, obj):
        raise IntegrityError("Exception occurs") # Here
        return super().response_change(request, obj)

现在，如果尝试添加数据：

添加数据除了正常尝试外还会重试 4 次，如下所示：

Exception occurs # Normal try
Exception occurs # 1st retry
Exception occurs # 2st retry
Exception occurs # 3rd retry
Exception occurs # 4th retry
[30/Dec/2022 22:01:41] "POST /admin/store/person/add/ HTTP/1.1" 302 0
[30/Dec/2022 22:01:41] "GET /admin/store/person HTTP/1.1" 301 0
[30/Dec/2022 22:01:41] "GET /admin/store/person/ HTTP/1.1" 200 21364
[30/Dec/2022 22:01:41] "GET /admin/jsi18n/ HTTP/1.1" 200 3195

最后，页面被重定向到“选择更改”页面不添加数据如下图：

接下来，如果尝试将数据从 John 更改为 David：

除了正常尝试之外，更改数据还会重试 4 次，如下所示：

Exception occurs # Normal try
Exception occurs # 1st retry
Exception occurs # 2st retry
Exception occurs # 3rd retry
Exception occurs # 4th retry
[30/Dec/2022 23:02:49] "POST /admin/store/person/678/change/ HTTP/1.1" 302 0
[30/Dec/2022 23:02:49] "GET /admin/store/person HTTP/1.1" 301 0
[30/Dec/2022 23:02:50] "GET /admin/store/person/ HTTP/1.1" 200 22512
[30/Dec/2022 23:02:50] "GET /admin/jsi18n/ HTTP/1.1" 200 3195

最后，页面被重定向到“选择更改”页面不改变数据如下所示：

接下来，使用@retry被覆盖的delete_view()每次出现异常时，除了正常尝试之外，默认可以重试2次删除数据，间隔1秒，如下图：

# "store/admin.py"

from django.db import DatabaseError, IntegrityError, transaction, router
from django.contrib import messages, admin
from django.shortcuts import redirect
from time import sleep
from .models import Person
from django.utils.decorators import method_decorator
from django.views.decorators.csrf import csrf_protect
csrf_protect_m = method_decorator(csrf_protect)

def retry(count, interval=1):
    # ...

@admin.register(Person)
class PersonAdmin(admin.ModelAdmin):

    @retry # Here
    @csrf_protect_m
    def delete_view(self, request, object_id, extra_context=None):
        with transaction.atomic(using=router.db_for_write(self.model)):
            return self._delete_view(request, object_id, extra_context)

所以，让我们提出IntegrityError异常在被覆盖的response_delete()如下所示：

# ...

@admin.register(Person)
class PersonAdmin(admin.ModelAdmin):

    @retry # Here
    @csrf_protect_m
    def delete_view(self, request, object_id, extra_context=None):
        with transaction.atomic(using=router.db_for_write(self.model)):
            return super()._delete_view(request, object_id, extra_context)

    def response_delete(self, request, obj_display, obj_id):
        raise IntegrityError("Exception occurs") # Here
        return super().response_delete(request, obj_display, obj_id)

现在，如果点击删除在“更改”页面:

然后点击是，我确定尝试删除数据：

除了正常尝试之外，删除数据还会重试 2 次，如下所示：

Exception occurs # Normal try
Exception occurs # 1st retry
Exception occurs # 2st retry
[30/Dec/2022 23:30:30] "POST /admin/store/person/680/delete/ HTTP/1.1" 302 0
[30/Dec/2022 23:30:30] "GET /admin/store/person HTTP/1.1" 301 0
[30/Dec/2022 23:30:30] "GET /admin/store/person/ HTTP/1.1" 200 22513
[30/Dec/2022 23:30:31] "GET /admin/jsi18n/ HTTP/1.1" 200 3195

最后，页面被重定向到“选择更改”页面不删除数据如下图：

最后，使用@retry被覆盖的delete_queryset()每次出现异常时，除了正常尝试之外，默认可以重试删除数据2次，间隔1秒，如下图。默认，交易不用于Django 管理操作:

# "store/admin.py"

from django.db import DatabaseError, IntegrityError, transaction, router
from django.contrib import messages, admin
from django.shortcuts import redirect
from time import sleep
from .models import Person
from django.utils.decorators import method_decorator
from django.views.decorators.csrf import csrf_protect
csrf_protect_m = method_decorator(csrf_protect)

def retry(count, interval=1):
    # ...

@admin.register(Person)
class PersonAdmin(admin.ModelAdmin):

    @retry # Here
    @transaction.atomic
    def delete_queryset(self, request, queryset):
        queryset.delete()

所以，让我们提出IntegrityError异常在被覆盖的delete_queryset()如下所示：

# ...

@admin.register(Person)
class PersonAdmin(admin.ModelAdmin):

    @retry # Here
    @transaction.atomic
    def delete_queryset(self, request, queryset):
        queryset.delete()
        raise IntegrityError("Exception occurs") # Here

现在，如果点击走在“更改”页面在“选择更改”页面:

然后点击是，我确定尝试删除数据：

删除数据除了正常尝试外还会重试 2 次，如下所示：

Exception occurs # Normal try
Exception occurs # 1st retry
Exception occurs # 2st retry
[31/Dec/2022 00:18:54] "POST /admin/store/person/ HTTP/1.1" 302 0
[31/Dec/2022 00:18:55] "GET /admin/store/person/ HTTP/1.1" 200 23013
[31/Dec/2022 00:18:55] "GET /admin/jsi18n/ HTTP/1.1" 200 3195

最后，页面被重定向到“选择更改”页面没有删除数据，但我不知道如何删除默认消息“已成功删除 2 人”。如下所示：

另外，如果使用@retry默认0.5间隔秒重试3次，需要分别将count = 2改为count = 3，将interval=1改为interval=0.5，如下图：

# "store/admin.py"

# ...
                 # ↓ Here
def retry(count, interval=0.5):
    def _retry(func):
        def core(*args, **kwargs):
            nonlocal count
            if callable(count):
                count = 3 # <= Here
            for i in range(count+1):
                try:
                    return func(*args, **kwargs)
                except DatabaseError as e:
                    print(e)
                    if i == count:            
                        messages.error(args[1], "Error occurred, try again!")                        
                        return redirect("/".join(args[1].path.split('/')[0:4]))
                    sleep(interval)
        return core
    
    if callable(count):
        return _retry(count)
    return _retry

# ...