Flask-Admin with additional field in relationship Many to Many

问题

I have two tables: "Product", "Ingredient" and "ProductIngredient"

class ProductIngredient(db.Model):
    __tablename__ = "product_ingredient"
    id = db.Column(db.Integer(), primary_key=True)
    product_id = db.Column('product_id', db.Integer, db.ForeignKey('product.id'))
    ingredient_id = db.Column('ingredient_id', db.Integer, db.ForeignKey('ingredient.id'))
    amount = db.Column(db.DECIMAL(10, 3))


class Ingredient(db.Model):
    __tablename__ = "ingredient"

    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(50))
    desc = db.Column(db.Text)


class Produto(db.Model):
    __tablename__ = "product"

    id = db.Column(db.Integer, primary_key=True)
    desc = db.Column(db.String(20))
    ingredients = db.relationship('Ingredient', secondary='product_ingredient', backref=db.backref('product', lazy='dynamic'))

Note that in the ProductIngredient class there is an amount field, which would take the quantity of each ingredient that makes up each product

setting the fields in admin, I get the following error

class ProdMV(ModelView):
    column_display_pk = False
    form_columns = [Product.desc, Ingredient.name, ProductIngredient.amount]
    column_auto_select_related = True
    column_hide_backrefs = False


admin.add_view(ProdMV(Product, db.session))

builtins.Exception

Exception: form column is located in another table and requires inline_models: Ingrediente.desc

I researched a lot about inline_models but found nothing that solved this problem

回答1:

The problem is that Product object can have several ingredients and they cannot be specified in one form field. So flask_admin hints that you should use inline_models. You need to add relationships to the ProductIngredient model:

class ProductIngredient(db.Model):
    __tablename__ = 'product_ingredient'

    id = db.Column(db.Integer, primary_key=True)
    product_id = db.Column(db.Integer, db.ForeignKey('product.id'))
    ingredient_id = db.Column(db.Integer, db.ForeignKey('ingredient.id'))
    amount = db.Column(db.DECIMAL(10, 3))

    product = db.relationship('Product', backref='products')
    ingredient = db.relationship('Ingredient', backref='ingredients')

And your ProductMV will look something like this:

class ProductMV(ModelView):
    form_columns = ('desc',)
    inline_models = ((
        ProductIngredient,
        {
            'form_columns': ('id', 'amount', 'ingredient'),
        }
    ),)

If you would not have ProductIngredient.amount field you could just type:

form_columns = [Product.desc, Product.ingredients]

This makes a field which allows adding items to it like tags.

来源：https://stackoverflow.com/questions/52637653/flask-admin-with-additional-field-in-relationship-many-to-many

标签

python

python-3.x

Flask

flask-sqlalchemy

flask-admin