【示例】“全名”字段显示完整的层级名称，例如：“一级分类 / 二级分类 / 三级分类”。

name = fields.Char(
    '名称',
    index=True,
    required=True
)
complete_name = fields.Char(
    '全名',
    compute='_compute_complete_name',
    store=True
)
parent_id = fields.Many2one(
    'product.category',
    '父分类',
    index=True,
    ondelete='cascade'
)

@api.depends('name', 'parent_id.complete_name')
def _compute_complete_name(self):
    for category in self:
        if category.parent_id:
            category.complete_name = '%s / %s' % (category.parent_id.complete_name, category.name)
        else:
            category.complete_name = category.name

【示例】计算产品品类下的产品数量。

product_count = fields.Integer(
    '# Products', compute='_compute_product_count',
    help="此类别下的产品数量（不考虑子类别）"
)

def _compute_product_count(self):
    read_group_res = self.env['product.template'].read_group([('categ_id', 'child_of', self.ids)], ['categ_id'], ['categ_id'])
    group_data = dict((data['categ_id'][0], data['categ_id_count']) for data in read_group_res)
    for categ in self:
        product_count = 0
        for sub_categ_id in categ.search([('id', 'child_of', categ.ids)]).ids:
            product_count += group_data.get(sub_categ_id, 0)
        categ.product_count = product_count