变形/漏勺HTML中的多对多关系选择字段

Question

我正在使用Pyramid框架并使用Deform包来呈现HTML表单,并给出了漏勺方案.我正在努力解决如何处理具有多对多关系的模式的问题.例如,我的s​​qlalchemy模型如下所示:

class Product(Base):
    """ The SQLAlchemy declarative model class for a Product object. """
    __tablename__ = 'products'

    id = Column(Integer, primary_key=True)
    name = Column(String(80), nullable=False)
    description = Column(String(2000), nullable=False)
    categories = relationship('Category', secondary=product_categories,
                               backref=backref('categories', lazy='dynamic'))


class Category(Base):                                                                                
    """ The SQLAlchemy declarative model class for a Category object. """                            
    __tablename__ = 'categories'

    id = Column(Integer, primary_key=True)                                                                                            
    name = Column(String(80), nullable=False)                                                                                                                                 
    products = relationship('Product', secondary=product_categories,                                 
                               backref=backref('products', lazy='dynamic'))


product_categories = Table('product_categories', Base.metadata,
    Column('products_id', Integer, ForeignKey('products.id')),
    Column('categories_id', Integer, ForeignKey('categories.id'))
)

如您所见,这是一个非常简单的模型,代表一个在线商店,其中一个产品可以属于一个或多个类别.在我的渲染形式中,我想有一个选择多个字段,我可以在其中选择几个不同的类别来放置产品.这是一个简单的漏勺模式:

def get_category_choices():

    all_categories = DBSession.query(Category).all()

    choices = []
    for category in all_categories:
        choices.append((category.id, category.name))

    return choices


class ProductForm(colander.Schema):
    """ The class which constructs a PropertyForm form for add/edit pages. """

    name = colander.SchemaNode(colander.String(), title = "Name",
                               validator=colander.Length(max=80),
                              )

    description = colander.SchemaNode(colander.String(), title="Description",
                                  validator=colander.Length(max=2000),
                                  widget=deform.widget.TextAreaWidget(rows=10, cols=60),
                                 )

    categories = colander.SchemaNode(
                colander.Set(),
                widget=deform.widget.SelectWidget(values=get_category_choices(), multiple=True),
                validator=colander.Length(min=1),
                )

而且,果然,我确实得到了所有字段的正确呈现,但是,categories字段似乎并没有"束缚"任何东西.如果我编辑一个我知道属于两个类别的产品,我希望select字段已经突出显示了这两个类别.进行更改(选择第三项)应导致DB更改,其中product_categories具有给定product_id的三行,每行具有不同的category_id.它可能是TMI,但我也使用类似于此的方法来读/写appstruct.

现在,我已经看到提及(并且再次)使用Mapping来处理这样的多对多关系字段,但是没有一个如何使用它的可靠示例.

提前感谢任何可以伸出援助之手的人.不胜感激.

Answer 1

在这个问题上,我出现在左侧,甚至没有为正确的区域提出正确的问题.我真正想要的是在多选漏勺SchemaNode中选择一些默认值.我把我的问题带到了铁塔 - 讨论谷歌集团,他们能够帮助我.当我在我的Product类中构建appstruct时,使用'set()',如下所示:

def appstruct(self):
    """ Returns the appstruct model for use with deform. """

    appstruct = {}
    for k in sorted(self.__dict__):
        if k[:4] == "_sa_":
            continue

        appstruct[k] = self.__dict__[k]

    # Special case for the categories
    appstruct['categories'] = set([str(c.id) for c in self.categories])

    return appstruct

然后,我将它(以及appstruct中的其他项目)一起传递给表单,并且正确地呈现HTML,并选择了所有类别.要在提交后应用appstruct,代码最终看起来像:

def apply_appstruct(self, appstruct):
    """ Set the product with appstruct from the submitted form. """

    for kw, arg in appstruct.items():

        if kw == "categories":
            categories = []
            for id in arg:
                categories.append(DBSession.query(Category).filter(Category.id == id).first())
            arg = categories

        setattr(self, kw, arg)

漏勺架构最终看起来像:

def get_category_choices():
    all_categories = DBSession.query(Category).all()
    return [(str(c.id), c.name) for c in all_categories]

categories = get_category_choices()

class ProductForm(colander.Schema):
    """ The class which constructs a ProductForm form for add/edit pages. """

    name = colander.SchemaNode(colander.String(), title = "Name",
                               validator=colander.Length(max=80),
                              )

    description = colander.SchemaNode(colander.String(), title="Description",
                                  validator=colander.Length(max=2000),
                                  widget=deform.widget.TextAreaWidget(rows=10, cols=60),
                                 )

    categories = colander.SchemaNode(
                colander.Set(),
                widget=deform.widget.SelectWidget(
                    values=categories,
                    multiple=True,
                ),
                validator=colander.Length(min=1),
                )

感谢所有看过的人.我道歉,我问的是错误的问题而不是保持简单.:-)