使用额外字段扩展Wagtail抽象模型的正确方法是什么？

问题描述

我有一个抽象的Wagtail模型，有几个 StreamField s。其中两个 StreamField 在管理视图中的另一个选项卡中，添加到 edit_handler 。


pre $ class AbstractHomePage（页）：
body = StreamField（
HomePageStreamBlock（），
default = '
）
headingpanel = StreamField（
HeadingPanelStreamBlock（），
default =''
）
sidepanel = StreamField（
SidePanelStreamBlock ），
default =''
）

class Meta：
abstract = True

search_fields = Page.search_fields + [index。 SearchField（'body'）]

content_panels = Page.content_panels + [
StreamFieldPanel（'body'），
]

pagesection_panels = [
StreamFieldPanel（'headingpanel'），
StreamFieldPanel（'sidepanel'），
]

edit_handler = TabbedInterface（[
ObjectList（content_panel
ObjectList（pagesection_panels，heading ='Page sections'），
ObjectList（Page.promote_panels），
ObjectList（Page.settings_panels，classname ='settings'），
]）


我想扩展此模型并添加一个字段：

  class Foo（AbstractHomePage）：
 extra = models.TextField（）
 
元：
 verbose_name = 'Foo'
 
 content_panels = [
 AbstractHomePage.content_panels [0]，＃title 
 FieldPanel（'extra'），
 AbstractHomePage.content_panels [-1]＃ streamfield 
] 
  

添加新的Foo页面时，管理面板中唯一可用的字段是来自 AbstractHomePage 的字段。新添加的字段在我更新 Foo 的 edit_handler 之前不可用：

  class Foo（AbstractHomePage）：
 extra = models.TextField（）
 
元：
 verbose_name =' Foo'
 
 content_panels = [
 AbstractHomePage.content_panels [0]，＃title 
 FieldPanel（'extra'），
 AbstractHomePage.content_panels [-1]＃streamfield 
] 
 
 edit_handler = TabbedInterface（[
 ObjectList（content_panels），
 ObjectList（AbstractHomePage.pagesection_panels，heading ='Page sections'），
 ObjectList （Page.promote_panels），
 ObjectList（Page.settings_panels，classname ='settings'），
]）
  

现在我的问题：我做错了还是不遵循良好的编码习惯？

如果我必须更新每个扩展模型的 edit_handler ，是否有更好的方法？必须确保新增的字段扩展了 AbstractHomePage ，每次都感觉到明确的样板 edit_handler 块丑陋。

解决方案

你必须重新定义 edit_handler的原因在 Foo 中，Python从顶部到底部评估 AbstractHomePage 类定义 - 指出它遇到的行：

  ObjectList（content_panels），
  

content_panels 被视为变量，而不是类属性，因此编辑处理程序是基于 content_panels 列表，因为它现在存在。在子类中重新定义 content_panels 不能覆盖此。

本质上，您正在寻找一种推迟方式构造edit_handler直到子类被定义。我看不到一个很好的方式直接进行，但是我想你可以通过一些挖掘Wagtail内部实现它，通过覆盖：

从$ w $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ b @cached_classmethod 
 def get_edit_handler（cls）：
 edit_handler = TabbedInterface（[
 ObjectList（cls.content_panels））
 ObjectList（cls.pagesection_panels，heading ='页面部分） ，
 ObjectList（cls.promote_panels），
 ObjectList（cls.settings_panels，classname ='settings'），
]）
返回edit_handler.bind_to_model（cls）
  

I have an abstract Wagtail model with a few StreamFields. Two of these StreamFields are in a separate tab in the admin view, which are added to the edit_handler.

class AbstractHomePage(Page):
    body = StreamField(
        HomePageStreamBlock(),
        default=''
    )
    headingpanel = StreamField(
        HeadingPanelStreamBlock(),
        default=''
    )
    sidepanel = StreamField(
        SidePanelStreamBlock(),
        default=''
    )

    class Meta:
        abstract = True

    search_fields = Page.search_fields + [index.SearchField('body')]

    content_panels = Page.content_panels + [
        StreamFieldPanel('body'),
    ]

    pagesection_panels = [
        StreamFieldPanel('headingpanel'),
        StreamFieldPanel('sidepanel'),
    ]

    edit_handler = TabbedInterface([
        ObjectList(content_panels),
        ObjectList(pagesection_panels, heading='Page sections'),
        ObjectList(Page.promote_panels),
        ObjectList(Page.settings_panels, classname='settings'),
    ])

I want to extend this model and add a field:

class Foo(AbstractHomePage):
    extra = models.TextField()

    Meta:
        verbose_name='Foo'

    content_panels = [
        AbstractHomePage.content_panels[0],     # title
        FieldPanel('extra'),
        AbstractHomePage.content_panels[-1]     # streamfield
    ]

When adding a new Foo page, the only fields available in the admin panel are the fields from the AbstractHomePage. The newly added field isn't available until I update Foo's edit_handler:

class Foo(AbstractHomePage):
    extra = models.TextField()

    Meta:
        verbose_name='Foo'

    content_panels = [
        AbstractHomePage.content_panels[0],     # title
        FieldPanel('extra'),
        AbstractHomePage.content_panels[-1]     # streamfield
    ]

    edit_handler = TabbedInterface([
        ObjectList(content_panels),
        ObjectList(AbstractHomePage.pagesection_panels, heading='Page sections'),
        ObjectList(Page.promote_panels),
        ObjectList(Page.settings_panels, classname='settings'),
    ])

And now to my question: Have I done something wrong or not followed good coding practices?

If I do have to update the edit_handler for each extending model, is there a better way to do this? Having to ensure that newly added fields for models extending the AbstractHomePage gets the explicit "boilerplate" edit_handler block each time feels really ugly. I see it as a massive violation of the DRY principle.

解决方案

The reason you have to redefine edit_handler in Foo is that Python evaluates the AbstractHomePage class definition from top to bottom - at the point that it encounters the line:

ObjectList(content_panels),

content_panels is treated as a variable, not a class property, and so the edit handler is built based on the content_panels list as it existed at that point. Redefining content_panels in the subclass can't override this.

Essentially, you're looking for a way to defer constructing the edit_handler until the subclass has been defined. I can't see a good way of doing that directly, but I think you could achieve it with a bit of digging into Wagtail internals, by overriding the Page.get_edit_handler method:

from wagtail.utils.decorators import cached_classmethod

class AbstractHomePage(Page):
    ...
    @cached_classmethod
    def get_edit_handler(cls):
        edit_handler = TabbedInterface([
            ObjectList(cls.content_panels),
            ObjectList(cls.pagesection_panels, heading='Page sections'),
            ObjectList(cls.promote_panels),
            ObjectList(cls.settings_panels, classname='settings'),
        ])
        return edit_handler.bind_to_model(cls)

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