如何以可读的显示下拉列表以模型形式显示烧瓶外键字段？

Question

我的模型中具有一对多关系。我正在使用wtforms_alchemy ModelForm创建表单，但是ForeignKey字段未显示为下拉字段，而是将整数显示为值。我尝试引用类似的问题并尝试了答案，例如，我在其中放置了__str__()和__repr__()函数，以便它们在下拉列表中返回一些可读且有意义的字符串，但那没有发生。有谁知道我还能怎么做？

Models.py-

class Product(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(20), nullable=False)
    location_id = db.Column(db.Integer, db.ForeignKey('location.id'))

    def __init__(self, name, location=None):
        self.name = name
        if location:
            self.location_id = location.id

    def __repr__(self):
        warehouse = Location.query.filter_by(id = self.location_id).first()
        qty = warehouse.get_product_quantity(self.name)
        return '{0}-{1}-{2}'.format(self.name, warehouse.name, qty)

class Location(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(20), unique=True, nullable=False)
    products = db.relationship('Product', backref='warehouse')

    def __init__(self, name):
        self.name = name

    def __repr__(self):
        return 'Location-{0}'.format(self.name)

class Movement(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    timestamp = db.Column(db.DateTime, nullable=False, default=datetime.utcnow)
    from_location_id = db.Column(db.Integer, db.ForeignKey("location.id"))
    to_location_id = db.Column(db.Integer, db.ForeignKey("location.id"))
    from_location = db.relationship(Location, lazy='joined', foreign_keys=[from_location_id], backref='from_location')
    to_location = db.relationship(Location, lazy='joined', foreign_keys=[to_location_id], backref='to_location')
    product_id = db.Column(db.Integer, db.ForeignKey('product.id'))
    product = db.relationship(Product, backref='movements')
    qty = db.Column(db.Integer)

forms.py-

class ProductForm(ModelForm, Form):
    class Meta:
        model = Product
        include = ['name']

class LocationForm(ModelForm, Form):
    class Meta:
        model = Location
        include = ['name']

class MovementForm(ModelForm, Form):
    class Meta:
        model = Movement
        include = ['from_location_id', 'to_location_id', 'product_id', 'qty']

Answer 1

由于ID是整数，因此WTForm-ALchemy会将表单字段转换为整数字段，您可以看到此here

因此，您可以按照here的说明强制使用选择字段>

如果您想提高可读性，可以使用QuerySelectField。

class MovementForm(ModelForm, Form):
    class Meta:
        model = Movement

    product = QuerySelectField(
        query_factory=lambda: Product.query.all(),
        get_pk=lambda a: a.id,
        get_label=lambda a: a.name,
        allow_blank=False,
    )
如果愿意，可以使用视图/路线来查询选项并将其传递给表单。

def movement_new():
    movement = Movement()
    form = MovementForm(obj=movement)

    products = [(c.id, c.name) for c in Product.query.all()]
    form.product_id.choices = products
    ...
Then on MovementForm

class MovementForm(ModelForm, Form):
    class Meta:
        model = Movement    ---> note tha the include was removed

    product_id = SelectField('Product', coerce=int)
  ...