敏捷类型的反向引用RelationList

我创建了两种敏捷类型：lab_equipment.py,class_activity.py.
class_activity类型包含与lab_activity类型的以下关系：

class_activity.py：

class IClassActivity(form.Schema, IImageScaleTraversable):
[...]
    dexteritytextindexer.searchable('apparatus')
    apparatus = RelationList(
        title=_(u"Apparatus"),
        description=_(u"Choose equipment used in this activity"),
        value_type=RelationChoice(
            source=ObjPathSourceBinder(
                object_provides=ILabEquipment.__identifier__,
                navigation_tree_query= {'path': {'query':'/Plone/ug-demos/equipment'}},
            ),
        ),
    )

[...]

现在,我需要在lab_equipment页面模板中列出class_activity类型的相关成员.

有没有办法将RelationList从class_activity类型反向引用到lab_activity类型,然后将此列表显示到页面模板中？

解决方法:

要检索向后引用(所有使用指定属性指向特定对象的对象),您不能简单地使用from_object或from_path,因为源对象存储在关系中而没有获取包装器.您应该使用from_id和helper方法来搜索IntId目录中的对象.

from Acquisition import aq_inner
from zope.component import getUtility
from zope.intid.interfaces import IIntIds
from zope.security import checkPermission
from zc.relation.interfaces import ICatalog


def back_references(source_object, attribute_name):
    """ Return back references from source object on specified attribute_name """
    catalog = getUtility(ICatalog)
    intids = getUtility(IIntIds)
    result = []
    for rel in catalog.findRelations(
                            dict(to_id=intids.getId(aq_inner(source_object)),
                                 from_attribute=attribute_name)
                            ):
        obj = intids.queryObject(rel.from_id)
        if obj is not None and checkPermission('zope2.View', obj):
            result.append(obj)
    return result

请注意,此方法不检查有效和有效期或内容语言.

在您的情况下,您需要从实验室设备浏览器视图的某些方法调用此方法,并将反向引用对象的列表传递到模板.例如：

class LabEquipmentView(BrowserView):

    def aparatus_backrefs(self):
        return back_references(self.context, 'apparatus')

附言我复制了自己一段时间前发布的敏捷问题#234的答案：http://code.google.com/p/dexterity/issues/detail?id=234&colspec=ID%20Type%20Status%20Priority%20Difficulty%20Milestone%20Owner%20Summary

标签：dexterity,python,plone
来源： https://codeday.me/bug/20191201/2080569.html