如何通过Odoo中的字段对树状视图进行分组或嵌套？

<tree>
    <field name="name"/>
    <field name="category"/>
    ...
</tree>

@api.model
def _group_by_category(self):
    return {
        'field': 'category',
        'group_expand': False,
        'group_by': 'category',
        'group_order': 'category desc',
        'group_label': 'Category',
    }

<tree>
    <field name="name"/>
    <field name="category"/>
    <group expand="0" string="Group By Category" context="{'group_by': 'category'}">
        <field name="category" widget="group_expand"/>
    </group>
</tree>