Flask-当数据库文件分离时，如何填充wtf形式的select字段

Question

我已经分离了模型文件和使用应用程序工厂。项目结构为像这样：

project/
|-- config.py
|-- core.py      # app factory definition which calls db.init_app(app)
|-- database.py  # models definition and 'db = SQLAlchemy()' is done here
|-- forms.py     # forms definition.
|-- __init__.py  # app = create_app() is done here
-- routes.py

我有两种模式：文章和分类。然后，在forms.py中，我尝试像这样：

class ArticleForm(Form):
    title = StringField()
    content = TextAreaField()
    category = SelectField(
        choices=[(c.id, c.name) for c in Category.query.all()]
    )

因此，Category.query.all()在应用程序上下文之外被调用，并引发以下问题：

RuntimeError: application not registered on db instance and no application
bound to current context

那么，我如何用数据库中的现有数据填充SelectField呢？

Answer 1

您可以使用WTForms的QuerySelectField扩展名：

from flask_wtf import Form
from wtforms.fields import StringField, TextAreaField
from wtforms.ext.sqlalchemy.fields import QuerySelectField
from database import Category
class ArticleForm(Form):
    title = StringField()
    content = TextAreaField()
    category = QuerySelectField(query_factory=lambda: Category.query.all())

Answer 2

这篇博客文章帮助了我，因为我无法获得公认的答案来完成我想要的工作。也去掉了一个导入。

http://kyle.marek-spartz.org/posts/2014-04-04-setting-wtforms-selection-fields-dynamically.html

我用了他的第二个技巧，这个问题看起来像

from flask_wtf import Form
from wtforms.fields import StringField, TextAreaField
from database import Category
class ArticleForm(Form):
    title = StringField()
    content = TextAreaField()
    category = SelectField()
    def __init__(self):
        super(ArticleForm, self).__init__()
        self.category.choices = [(c.id, c.name) for c in Category.query.all()]