ORM-1 字段默认值

  当在odoo页面新建一条记录的时候,前端会通过rpc调用后端模型的default_get 函数,根据前端传入的字段列表,来获取相对应的字段默认值。
	# odoo/models.py
    @api.model
    def default_get(self, fields_list):
        """ default_get(fields_list) -> default_values

        Return default values for the fields in ``fields_list``. Default
        values are determined by the context, user defaults, and the model
        itself.

        :param list fields_list: names of field whose default is requested
        :return: a dictionary mapping field names to their corresponding default values,
            if they have a default value.
        :rtype: dict

        .. note::

            Unrequested defaults won't be considered, there is no need to return a
            value for fields whose names are not in `fields_list`.
		
        """
        defaults = {}
        parent_fields = defaultdict(list)
        ir_defaults = self.env['ir.default'].get_model_defaults(self._name)

        for name in fields_list:
            # 1. look up context
            key = 'default_' + name
            if key in self._context:
                defaults[name] = self._context[key]
                continue

            # 2. look up ir.default
            if name in ir_defaults:
                defaults[name] = ir_defaults[name]
                continue

            field = self._fields.get(name)

            # 3. look up field.default
            if field and field.default:
                defaults[name] = field.default(self)
                continue

            # 4. delegate to parent model
            if field and field.inherited:
                field = field.related_field
                parent_fields[field.model_name].append(field.name)

        # convert default values to the right format
        #
        # we explicitly avoid using _convert_to_write() for x2many fields,
        # because the latter leaves values like [(Command.LINK, 2),
        # (Command.LINK, 3)], which are not supported by the web client as
        # default values; stepping through the cache allows to normalize
        # such a list to [(Command.SET, 0, [2, 3])], which is properly
        # supported by the web client
        for fname, value in defaults.items():
            if fname in self._fields:
                field = self._fields[fname]
                value = field.convert_to_cache(value, self, validate=False)
                defaults[fname] = field.convert_to_write(value, self)

        # add default values for inherited fields
        for model, names in parent_fields.items():
            defaults.update(self.env[model].default_get(names))

        return defaults

1、该函数的作用

    函数文档说的很清楚了,我在赘述一遍。
    该函数根据传入的字段名返回响应的默认值,默认值是由context,用户定义以及模型本身决定的。
    输入参数: field_list  字段名称列表。
    返回值: 一个字典,key是字段名称,value是该字段的默认值
    注意: 该函数只返回请求列表中的字段的默认值。至于有哪些字段,是由前端视图决定的。

2、设置默认值的四种方式

从代码中可以看到,获取字典的默认值,按照优先级有四种方式:

2.1 上下文context

action

        <record id="action_move_out_invoice_type" model="ir.actions.act_window">
            <field name="name">Invoices</field>
            <field name="res_model">account.move</field>
            <field name="view_mode">tree,kanban,form</field>
            <field name="view_id" ref="view_out_invoice_tree"/>
            <field name="search_view_id" ref="view_account_invoice_filter"/>
            <field name="domain">[('move_type', '=', 'out_invoice')]</field>
            <field name="context">{'default_move_type': 'out_invoice'}</field>
            <field name="help" type="html">
              <p class="o_view_nocontent_smiling_face">
                Create a customer invoice
              </p><p>
                Create invoices, register payments and keep track of the discussions with your customers.
              </p>
            </field>
        </record>

2.2 ir.default

@api.model
    def get(self, model_name, field_name, user_id=False, company_id=False, condition=False):
        """ Return the default value for the given field, user and company, or
            ``None`` if no default is available.

            :param model_name:
            :param field_name:
            :param user_id: may be ``False`` for all users, ``True`` for the
                            current user, or any user id
            :param company_id: may be ``False`` for all companies, ``True`` for
                               the current user's company, or any company id
            :param condition: optional condition that restricts the
                              applicability of the default value; this is an
                              opaque string, but the client typically uses
                              single-field conditions in the form ``'key=val'``.
        """
        if user_id is True:
            user_id = self.env.uid
        if company_id is True:
            company_id = self.env.company.id

        field = self.env['ir.model.fields']._get(model_name, field_name)
        default = self.search([
            ('field_id', '=', field.id),
            ('user_id', '=', user_id),
            ('company_id', '=', company_id),
            ('condition', '=', condition),
        ], limit=1)
        return json.loads(default.json_value) if default else None

从代码看, 可以对模型中的某一字典,根据不同的用户、公司、条件设置不同的默认值。
但是实际开发中很少用。

2.3 字段的默认值

这是最常见的设置默认值的一种方式
有三种设置方法:
1、 直接设置

active = fields.Boolean(default=True)

2、设置为一个函数

example_date = fields.Date(string='Date example', default=_default_example_date, store=False)

3 设置为lamda函数

 user_id = fields.Many2one('res.users', default= lambda self: self.env.user) 

2.4 通过委托继承的父表的默认值(_inherits)

关于委托继承,这里就不具体描述了。 简单理解就是数据存储在父表中,但是可以当自己的字段用。
通过一个many2one字段进行关联。

3 重写default_get

某些场景下,我们可以model中重写这个函数,加上我们自己的逻辑,比如:

    def default_get(self, fields_list):
    	# 先调用父类方法
        defaults = super().default_get(fields_list)
		# 然后再执行自己的逻辑去对defaults 进行修改,最后再将它返回。
        if 'journal_id' in defaults and 'date' in fields_list:
            last_line = self.search([
                ('journal_id', '=', defaults.get('journal_id')),
                ('state', '=', 'posted'),
            ], limit=1)
            statement = last_line.statement_id
            if statement:
                defaults.setdefault('date', statement.date)
            elif last_line:
                defaults.setdefault('date', last_line.date)

        return defaults

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