Examples: using ColanderAlchemy with DeformΒΆ

When using ColanderAlchemy, the resulting Colander schema will reflect the configuration on the mapped class, as shown in the code below:

from colanderalchemy import SQLAlchemySchemaNode

from sqlalchemy import Enum, ForeignKey, Integer, Unicode
from sqlalchemy.ext.declarative import declarative_base

Base = declarative_base()

class Phone(Base):
    __tablename__ = 'phones'

    person_id = Column(Integer, ForeignKey('persons.id'),
    number = Column(Unicode(128), primary_key=True)
    location = Column(Enum('home', 'work'))

class Person(Base):
    __tablename__ = 'persons'

    id = Column(Integer, primary_key=True)
    name = Column(Unicode(128), nullable=False)
    surname = Column(Unicode(128), nullable=False)
    phones = relationship(Phone)

schema = SQLAlchemySchemaNode(Person)

The resulting schema from the code above is the same as what would be produced by constructing the following Colander schema by hand:

import colander

class Phone(colander.MappingSchema):
    person_id = colander.SchemaNode(colander.Int())
    number = colander.SchemaNode(
        validator=colander.Length(0, 128)
    location = colander.SchemaNode(
        validator=colander.OneOf(['home', 'work']),

class Phones(colander.SequenceSchema):
    phones = Phone(missing=[])

class Person(colander.MappingSchema):
    id = colander.SchemaNode(colander.Int(),
    name = colander.SchemaNode(
        validator=colander.Length(0, 128)
    surname = colander.SchemaNode(
        validator=colander.Length(0, 128)
    phones = Phones(missing=[])

schema = Person()

Note the various configuration aspects like field length and the like will automatically be mapped. This means that getting a Deform form to use ColanderAlchemy is as simple as using any other Colander schema:

from colanderalchemy import SQLAlchemySchemaNode
from deform import Form

# Using Colander requires manually constructing the schema
# person = Person()

# Using ColanderAlchemy is easy!
person = SQLAlchemySchemaNode(Person)

form = Form(person, buttons=('submit',))

Keep in mind that if you want additional control over the resulting Colander schema and nodes produced (such as controlling a node’s title, description, widget or more), you are able to provide appropriate keyword arguments declaratively within the SQLAlchemy model as part of the respective info argument to a sqlalchemy.Column or sqlalchemy.orm.relationship() declaration. For more information, see Customization.