TurboGears – Scaffolding


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Gearbox toolkit contains scaffold command, which is very useful to quickly create new components of TurboGears application. An application generated by quickstart command of gearbox has a skeleton template in the model folder (model.py.template), a templates folder (template.html.template) and a controllers folder (controller.py.template). These ‘.template’ files are used as basis for creating new scaffolds for an application

For example, in order to create a new model named mymodel, simply run the following command −

gearbox scaffold model mymodel

This command will generate model/mymodel.py with newmodel class defined in it.

# -*- coding: utf-8 -*-
"""Mymodel model module."""
from sqlalchemy import *
from sqlalchemy import Table, ForeignKey, Column
from sqlalchemy.types import Integer, Unicode, DateTime, LargeBinary
from sqlalchemy.orm import relationship, backref
from hello.model import DeclarativeBase, metadata, DBSession

class Mymodel(DeclarativeBase):
   __tablename__ = 'mymodels'
   
   uid = Column(Integer, primary_key = True)
   data = Column(Unicode(255), nullable = False)
   
   user_id = Column(Integer, ForeignKey('tg_user.user_id'), index = True)
   user = relationship('User', uselist = False,
      backref = backref('mymodels',cascade = 'all, delete-orphan'))
   __all__ = ['Mymodel']

The users can now make modifications in the table structure as per their requirement and then import it inside model/__init__.py to make the model available inside the application.

In order to create a model, a controller class to handle it and an index page all these three components can be created simultaneously by the following command.

gearbox scaffold model controller template mymodel

This command will result in controllers\mymodel.py in which the MymodelController class is duly defined.

# -*- coding: utf-8 -*-
"""Mymodel controller module"""

from tg import expose, redirect, validate, flash, url
# from tg.i18n import ugettext as _
# from tg import predicates

from hello.lib.base import BaseController
# from hello.model import DBSession

class MymodelController(BaseController):
   # Uncomment this line if your controller requires an authenticated user
   # allow_only = predicates.not_anonymous()
   
   @expose('hello.templates.mymodel')
   def index(self, **kw):
      return dict(page = 'mymodel-index')

To start using this controller, mount it inside your application RootController just to define an instance of MymodelController. Add these lines in the controllers\root.py −

From hello.controller.mymodel import MymodelController

class RootController(BaseController): mymodel = MymodelController()

A template scaffold templates\mymodel.html will also be created in the templates folder. It will act as an index page for ‘/mymodel’ URL.

The generated mymodel.html file in the templates folder will be as follows −

<html xmlns = "http://www.w3.org/1999/xhtml"
   xmlns:py = "http://genshi.edgewall.org/"
   xmlns:xi = "http://www.w3.org/2001/XInclude">
	
   <xi:include href = "master.html" />
	
   <head>
      <title>Mymodel</title>
   </head>
	
   <body>
      <div class = "row">
         <div class = "col-md-12">
            <h2>Mymodel</h2>
            <p>Template page for Mymodel</p>
         </div>
      </div>
   </body>
	
</html>


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