如何在为渲染提供数据期间动态加载 ModelView 中 form_extra_fields 之一的选择？

Question

我有一个 User admin ModelView 和 form_extra_field constituency 我想让它动态加载choices（它是SelectField）。此视图的模型是 User，它将选区存储为项目的 id。

我尝试从远程 API 加载 choices 但肯定是加载这些东西的时间错误，因为 RuntimeError: 在应用程序外部工作context. 它发生在迁移命令 ...venv/bin/flask db init -d ctiweb/migrations 处。我从需要有应用程序上下文的配置对象中读取了一些 API_KEY ...

所以解决方案是在服务或呈现时加载选择。我不想在自定义模板中使用解决方案，而是希望在自定义管理 ModelView 中为 User 模型提供解决方案。

有这样的解决方案吗？我可以重载已经具有应用程序上下文的 ModelView 的某些方法吗（所以它是在提供数据或呈现模板期间）？

部分源代码来自models.py

class User(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    username = db.Column(db.String(80), unique=True, nullable=False)
    password_hash = db.Column(db.String(128))
    email = db.Column(db.String(255), nullable=False)
    is_superuser = db.Column(db.Boolean())
    constituency_id = db.Column(db.Integer())

    def __str__(self):
        return self.username

    @property
    def password(self):
        raise AttributeError("not readable attribute")

    @password.setter
    def password(self, password):
        self.password_hash = generate_password_hash(password)

    def verify_password(self, password):
        return check_password_hash(self.password_hash, password)

部分源代码来自admin.py

from flask_admin.contrib.sqla import ModelView

class UserAdminModelView(ModelView):

    def serve_constituency_choices():
        consituencies = (
            get_constituency(constituency_id) for constituency_id in get_constituencies()
        )
        return ((constituency['id'], constituency['name']) for constituency in consituencies)

    column_list = ['username', 'email', 'is_superuser']
    form_columns = ['username', 'email', 'password', 'is_superuser', 'constituency']
    form_extra_fields = {
        'password': PasswordField('Password'),
        'constituency': SelectField('Constituency', choices=serve_constituency_choices())
    }

Answer 1

ModelView 上有一些方法 - create_form 和 edit_form，它们可以被重载，并且 return 从远程 API 加载正确的选择。查看文档 https://flask-admin.readthedocs.io/en/latest/api/mod_model/#flask_admin.model.BaseModelView.create_form and https://flask-admin.readthedocs.io/en/latest/api/mod_model/#flask_admin.model.BaseModelView.edit_form .

class UserAdminModelView(ModelView):

    column_list = ['username', 'email', 'is_superuser']
    form_columns = ['username', 'email', 'password', 'is_superuser', 'constituency']
    form_extra_fields = {
        'password': PasswordField('Password'),
        'constituency': SelectField('Constituency', coerce=int)
    }

    class ConstituencyChoices(Iterator):
        def __init__(self, constituencies, first_item=None):
            self.first_item = first_item
            self.constituencies = constituencies

        def __next__(self):
            if self.first_item is not None:
                res = self.first_item
                self.first_item = None
                return res
            constituency = self.constituencies.__next__()
            res = (constituency['id'], constituency['name'])
            return res

    def serve_constituency_choices(self):
        constituencies = (
            get_constituency(constituency_id) for constituency_id in get_constituencies()
        )
        return self.ConstituencyChoices(constituencies, (0, "-----"))

    def create_form(self, obj=None):
        form = super().create_form(obj=obj)
        form.constituency.choices = self.serve_constituency_choices()
        return form

    def edit_form(self, obj=None):
        form = super().edit_form(obj=obj)
        form.constituency.choices = self.serve_constituency_choices()
        return form

Answer 2

实际上，我终于找到了一个 更简单的 解决方案 - 仅在选区选择上使用 class 迭代器。我认为比第一个好:-)

class ConstituencyChoices(Iterator):
    def __init__(self, first_item=None):
        self.first_item = first_item
        self.constituencies = None

    def __next__(self):
        if self.first_item is not None:
            res = self.first_item
            self.first_item = None
            return res
        if self.constituencies is None:
            self.constituencies = (
                get_constituency(constituency_id) for constituency_id in get_constituencies()
            )
        constituency = self.constituencies.__next__()
        res = (constituency['id'], constituency['name'])
        return res

# pylint: disable=too-many-ancestors
class UserAdminModelView(ModelView):

    column_list = ['username', 'email', 'is_superuser']
    form_columns = ['username', 'email', 'password', 'is_superuser', 'constituency']
    form_extra_fields = {
        'password': PasswordField('Password'),
        'constituency': SelectField(
            'Constituency',
            coerce=int,
            choices=ConstituencyChoices(
                (0, "--- {} ---".format(_('no constituency')))
            )
        )
    }

如何在为渲染提供数据期间动态加载 ModelView 中 form_extra_fields 之一的选择？

How to load choices for one of form_extra_fields in ModelView dynamically during serving data for rendering?

flask

sqlalchemy

flask-admin