如何在 flask-admin 中呈现给用户的编辑表单之前访问模型字段值？

Question

我有模型用户：

 class User(db.Model):

    __tablename__ = "users"

    id = db.Column(db.Integer, primary_key=True, autoincrement=True)
    username = db.Column(db.String(50), unique=True, nullable=False)
    token_life_time = db.Column(db.Integer, nullable=False)

和来自 flask-admin 的 ModelView：

class UserModelView(ModelView):

    column_list = ('id', 'username', 'token_life_time')
    form_create_rules = ('username', 'token_life_span') # custom field, that doesn't exist in actual model
    form_edit_rules = ('username', 'token_life_time', 'new_token_life_time')
    form_extra_fields = {
        'token_life_span': StringField(default='1-0-0-0', validators=[DataRequired()]),
        'new_token_life_time': StringField() # how to put here actual value from model.token_life_time as default value in EDIT form ???
    }

    column_formatters = dict(
        token_life_time=lambda v, c, m, p: UserModelView.convert_seconds_to_human_readable(m.token_life_time)
    )
    
    def on_model_change(self, form, model, is_created):
        token_time = form.data.get('token_life_span', None)
        if token_time:
            model.token_life_time = self.convert_to_seconds(token_time) # my custom function  that converts string of format (days-hours-minutes-seconds, example: 1-8-23-15) into seconds for storing in DB int type

我想在 EDIT 表单呈现给用户之前访问 model.token_life_time 值并将其从秒数转换为人类可读的字符串（包括天数、小时数等）。然后将转换后的值作为默认值放入编辑表单的自定义字段中（new_token_life_time）。

问题是 - 如何从模型中访问实际值，然后将转换后的值作为默认值以编辑形式放入自定义字段？？？

Answer 1

覆盖视图的 edit_form 方法 - 请参阅 documentation。

类似于以下内容：

class UserModelView(ModelView):

    def edit_form(self, obj=None):
        form = super().edit_form(obj=obj)
        # calculate token_life_span
        _token_life_span = get_token_life_span(obj.token_life_time)
        form.token_life_span.data = _token_life_span
        return form

如何在 flask-admin 中呈现给用户的编辑表单之前访问模型字段值？

How to access model field value before edit form presented to user in flask-admin?

flask

python-3.x

flask-admin