Sessions in Java

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The signin form (/sessions/new)
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Listing 95 HTML for the signin form produced by Listing 94
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<form action="/sessions" method="post"> <div class="field"> <label for="session_email">Email</label><br /> <input id="session_email" name="session[email]" size="30" type="text" /> </div> <div class="field"> <label for="session_password">Password</label><br /> <input id="session_password" name="session[password]" size="30" type="password" /> </div> <div class="actions"> <input id="session_submit" name="commit" type="submit" value="Sign in" /> </div> </form>
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9: Sign In, Sign Out
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Comparing Listing 95 with Listing 85, you might be able to guess that submitting this form will result in a params hash where params[:session][:email] and params[:session][:password] correspond to the email and password fields Handling this submission and, in particular, authenticating users based on the submitted email and password is the goal of the next two sections
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92 Signin Failure
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As in the case of creating users (signup), the first step in creating sessions (signin) is to handle invalid input We ll start by reviewing what happens when a form gets submitted, and then arrange for helpful error messages to appear in the case of signin failure (as mocked up in Figure 93) Finally, we ll lay the foundation for successful
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A mockup of signin failure
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Signin Failure
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signin (Section 93) by evaluating each signin submission based on the validity of its email/password combination
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921 Reviewing Form Submission
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Let s start by defining a minimalist create action for the Sessions controller (Listing 96), which does nothing but render the new view Submitting the /sessions/new form with blank fields then yields the result shown in Figure 94
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Listing 96 A preliminary version of the Sessions create action
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app/controllers/sessions_controllerrb
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class SessionsController < ApplicationController def create render 'new' end end
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Carefully inspecting the debug information in Figure 94 shows that, as hinted at the end of Section 912, the submission results in a params hash containing the email and password under the key :session:
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--- !map:ActiveSupport::HashWithIndifferentAccess commit: Sign in session: !ActiveSupport::HashWithIndifferentAccess password: "" email: "" authenticity_token: BlO65PA1oS5vqrv591dt9B22HGSWW0HbBtoHKbBKYDQ= action: create controller: sessions
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As with the case of user signup (Figure 86) these parameters form a nested hash like the one we saw in Listing 45 In particular, params contains a nested hash of the form
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{ :session => { :password => "", :email => "" } }
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9: Sign In, Sign Out
The initial failed signin, with create as in Listing 96
This means that
params[:session]
is itself a hash:
{ :password => "", :email => "" }
As a result,
params[:session][:email]
Signin Failure
is the submitted email address and
params[:session][:password]
is the submitted password In other words, inside the create action the params hash has all the information needed to authenticate users by email and password Not coincidentally, we have already developed exactly the method needed: Userauthenticate from Section 724 (Listing 712) Recalling that authenticate returns nil for an invalid authentication, our strategy for user signin can be summarized as follows:
def create user = Userauthenticate(params[:session][:email], params[:session][:password]) if usernil # Create an error message and re-render the signin form else # Sign the user in and redirect to the user's show page end end
922 Failed Signin (Test and Code)
In order to handle a failed signin attempt, first we need to determine that it s a failure The tests follow the example from the analogous tests for user signup (Listing 86), as shown in Listing 97
Listing 97 Tests for a failed signin attempt
spec/controllers/sessions_controller_specrb
require 'spec_helper' describe SessionsController do render_views describe "POST 'create'" do describe "invalid signin" do before(:each) do
9: Sign In, Sign Out
@attr = { :email => "email@examplecom", :password => "invalid" } end it "should re-render the new page" do post :create, :session => @attr responseshould render_template('new') end it "should have the right title" do post :create, :session => @attr responseshould have_selector("title", :content => "Sign in") end
it "should have a flashnow message" do post :create, :session => @attr flashnow[:error]should = /invalid/i end end end end
The application code needed to get these tests to pass appears in Listing 98 As promised in Section 921, we extract the submitted email address and password from the params hash, and then pass them to the Userauthenticate method If the user is not authenticated (ie, if it s nil), we set the title and re-render the signin form4 We ll handle the other branch of the if-else statement in Section 93; for now we ll just leave a descriptive comment