Django V Rails

A talk I gave to pybelfast on the 26th October 2016

Transcript

1. django v rails
   Stephen McCullough
   

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2. who am i
   • Stephen McCullough
   • @swmcc on the interwebs
   • Senior Software Engineer @ ShopKeep
   • We are hiring - python/ruby - talk to me after
   

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4. Translation
   • models
   • template
   • views
   • URL
   • models
   • views
   • controllers
   • routes
   django rails
   

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5. Tools
   • pypi
   • pip
   • pdb
   • virtualenv
   • rubygems
   • bundler
   • debugger
   • rvm/rbenv
   django rails
   

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6. Comparison
   • generic templates
   • models
   • admin interface
   • authentication
   • south
   • scaffolding
   • active record
   • active admin
   • devise
   • migrations
   django rails
   

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7. models
   To create a model in rails you run a command
   rails generate model SomeModel 

   somerow:string
   class SomeModel < ActiveRecord::Base

   

   end
   create_table “some_model”, force => true do |t|
   t.string “somerow”
   end
   

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8. models
   To create a model in django you run a command
   class SomeModel(models.Model):

   somerow = models.CharField()
   created_at = models.DateTimeField(auto_now_add=True)
   upcated_at = models.DateTimeField(auto_now=True)
   

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9. migrations
   To create a migration in rails you run a command
   rails generate migration AddAnotherThingToSomeModel
   something_else:string
   

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10. migrations
    To create a migration in django you edit model.py
    class SomeModel(models.Model):

    somerow = models.CharField()
    something_else = models.CharField()
    created_at = models.DateTimeField(auto_now_add=True)
    upcated_at = models.DateTimeField(auto_now=True)
    end
    python manage.py schemamigration somemodel —auto
    python manage.py migrate somemodel
    

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11. queries
    In rails you can be quite expressive with your queries.
    Client.where(created_at: (Time.now.midnight -
    1.day)..Time.now.midnight)
    Model.where('field >= ?', value)
    Model.objects.filter(field__gt=value)
    

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12. controllers
    In rails the controllers look nice.
    class OrdersController < ApplicationController
    def index
    @orders = Order.where(active: true)
    end
    def show
    @order = Order.find(params[:id])
    end
    def new
    @order = Order.new
    end
    def create
    @order = Order.new(params[:order])
    if @order.save
    redirect_to @order
    else
    render 'new'
    end
    end
    end
    

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13. controllers
    In django the controllers don’t look so nice.
    # django usually calls the 'show' method 'detail'
    # the product_id parameter comes from the routing
    def detail(request, product_id):
    p = Product.objects.get(pk=product_id) # pk = primary key
    # renders detail.html with the third parameter passed as context
    return render(request, 'products/detail.html', {'product': p})
    def create(request):
    # check if form was submitted
    if request.method == 'POST':
    # similar to RoR' 'create' action
    form = ProductForm(request.POST) # A form bound to the POST data
    if form.is_valid(): # All validation rules pass
    new_product = form.save()
    return HttpResponseRedirect(new_product.get_absolute_url())
    else:
    # similar to RoR' 'new' action
    form = ProductForm() # An empty form
    return render(request, 'products/create.html', { 'form': form })
    

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14. controllers
    In django controllers don’t look so nice.
    # Supposes the routing passed in a parameter called 'pk'
    # containing the object id and uses it for fetching the object.
    # Automatically renders the view /products/product_detail.html
    # and passes product as a context variable to the view.
    class ProductDetail(DetailView):
    model = Product
    # Generates a form for the given model. If data is POSTed,
    # automatically validates the form and creates the resource.
    # Automatically renders the view /products/product_create.html
    # and passes the form as a context variable to the view.
    class ProductCreate(CreateView):
    model = Product
    

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15. views
    Forms
    <%= form_tag("/contact", method: "post") do %>
    <%= label_tag(:subject, "Subject:") %>
    <%= text_field_tag(:subject) %>
    <%= label_tag(:message, "Message:") %>
    <%= text_field_tag(:message) %>
    <%= label_tag(:subject, "Sender:") %>
    <%= text_field_tag(:sender) %>
    <%= label_tag(:subject, "CC myself:") %>
    <%= check_box_tag(:sender) %>
    <%= submit_tag("Search") %>
    <% end %>
    

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16. views
    Forms
    class ContactForm(forms.Form):
    subject = forms.CharField(max_length=100)
    message = forms.CharField()
    sender = forms.EmailField()
    cc_myself = forms.BooleanField(required=False)
    def contact(request):
    if request.method == 'POST':
    form = ContactForm(request.POST)
    if form.is_valid():
    return HttpResponseRedirect('/thanks/') # Redirect after POST
    else:
    form = ContactForm() # An unbound form
    return render(request, 'contact.html', { 'form': form }
    

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17. views
    Forms
    class ContactForm(forms.Form):
    subject = forms.CharField(max_length=100)
    message = forms.CharField()
    sender = forms.EmailField()
    cc_myself = forms.BooleanField(required=False)
    def contact(request):
    if request.method == 'POST':
    form = ContactForm(request.POST)
    if form.is_valid():
    return HttpResponseRedirect('/thanks/') # Redirect after POST
    else:
    form = ContactForm() # An unbound form
    return render(request, 'contact.html', { 'form': form }
    

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18. views
    Forms
    
    {{ form.as_p }}
    
    
    

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19. routing
    # automatically maps GET /products/:id to products#show
    # GET /products to products#index
    # POST /products to products#create
    # DELETE /products/:id to products#destroy
    # etc.
    resources :products
    urlpatterns = patterns('',
    # matches the detail method in the products controller
    url(r'^products/(?P\d+)/$', products.views.DetailView.as_view(),
    name='detail'),
    # matches the index method, you get the gist
    url(r'^products/$', products.views.IndexView.as_view(), name='index'),
    url(r'^products/create/$', products.views.CreateView.as_view(),
    name='create'),
    url(r'^products/(?P\d+)/delete/$', products.views.DeleteView.as_view(),
    name='delete'),
    )
    

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20. testing
    class UsersControllerTest < ActionController::TestCase
    test "should get index" do
    get :index # GET request to the index action
    assert_response :success # request returned 200
    # assigns is a hash containing all instance variables
    assert_not_nil assigns(:users)
    end
    end
    class UsersTest(unittest.TestCase):
    def setUp(self):
    self.client = Client()
    def test_index(self):
    """ should get index """
    response = self.client.get(reverse('users:index'))
    self.assertEqual(response.status_code, 200)
    self.assertIsNotNone(response.context['users'])
    

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21. Conclusion
    • Both are outstanding frameworks
    • You can’t go wrong my picking either one.
    • I prefer django, marginally
    • It's not hard to switch from one to another
    

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