使用ViewFlow创建工作流执行makemigrations报错：AttributeError

我是ViewFlow新手，正尝试创建工作流，已编写flows.py、models.py、helloworld/urls.py代码（代码如下）。执行python manage.py makemigrations命令时，出现错误：AttributeError: module 'viewflow.nodes' has no attribute 'Obsolete'，请问问题出在哪里或遗漏了什么？

代码文件 #

flows.py #

from viewflow import rest

from viewflow.base import this, Flow

from viewflow.rest import flow
from viewflow.rest.views import CreateProcessView

from .models import FormInstanceProcess


@rest.register
class FormFlow(Flow):
    process_class = FormInstanceProcess

    create_form = (
        flow.Start(CreateProcessView, fields=["asset", "attributes"])
        .Available(
            lambda user: True
        )
        .Next(this.end_process)
    )

end_process = flow.End()

models.py #

from django.db import models
from django.contrib.auth import get_user_model

from viewflow.models import Process

User = get_user_model()


class FormInstanceProcess(Process):
    asset = models.CharField(max_length=236)

helloworld/urls.py #

from django.urls import path, include
from viewflow.rest.viewset import FlowViewSet
from .flows import FormFlow

form_flow_urls = FlowViewSet(FormFlow).urls


app_name = "helloworld"
urlpatterns = [
    path("workflow/", include((form_flow_urls, "form"), namespace="form_flow")),

]

问题原因及解决方法 #

这个错误核心是ViewFlow版本不兼容+代码结构不符合当前版本规范导致的，具体修复步骤如下：

1. 统一ViewFlow REST模块的导入路径
   你当前混合导入了viewflow.base和viewflow.rest的内容，REST工作流应统一使用viewflow.rest下的Flow和this：
   修改flows.py的导入部分：

   from viewflow import rest
   from viewflow.rest import this, Flow  # 替换原viewflow.base的导入
   from viewflow.rest import flow
   from viewflow.rest.views import CreateProcessView
   from .models import FormInstanceProcess
   

2. 调整流程节点的定义位置
   流程的End节点必须定义在Flow类内部，不能放在全局作用域：
   修改flows.py的流程结构：

   @rest.register
   class FormFlow(Flow):
       process_class = FormInstanceProcess
   
       create_form = (
           flow.Start(CreateProcessView, fields=["asset"])  # 注意：模型中无attributes字段，需移除
           .Available(lambda user: True)
           .Next(this.end_process)
       )
   
       end_process = flow.End()  # 移至类内部
   

3. 修正字段不一致问题
   你的FormInstanceProcess模型仅定义了asset字段，但Start节点中指定了fields=["asset", "attributes"]，这会导致后续运行报错，需删除attributes或在模型中添加对应字段。

4. 确保使用稳定版ViewFlow
   运行pip show viewflow查看当前版本，若为测试版或旧版本，升级至官方稳定版：

   pip install --upgrade viewflow
   

完成以上修改后，重新执行python manage.py makemigrations和python manage.py migrate即可正常生成迁移文件。

内容的提问来源于stack exchange，提问作者Pooja Kumari