feed username into login when failure

app.rb

@@ -134,11 +134,13 @@ end
 
 post '/signin' do
   dashboard_if_signed_in
+
   if Site.valid_login? params[:username], params[:password]
     site = Site[username: params[:username]]
 
     if site.is_banned
       flash[:error] = 'Invalid login.'
+      flash[:username] = params[:username]
       redirect '/signin'
     end
 
@@ -146,6 +148,7 @@ post '/signin' do
     redirect '/dashboard'
   else
     flash[:error] = 'Invalid login.'
+    flash[:username] = params[:username]
     redirect '/signin'
   end
 end

views/layout.slim

@@ -24,6 +24,7 @@ html
     .page
       .container
         - flash.keys.each do |key|
+          - next unless %i{success error}.include? key
           div class="alert alert-#{key}"
             button.close type="button" data-dismiss="alert" ×
             == flash[key]

views/signin.slim

@@ -6,7 +6,7 @@
         input name="csrf_token" type="hidden" value="#{csrf_token}"
 
         fieldset.col-60 style="margin:0 auto"
-          input name="username" type="text" placeholder="Your username" class="input-Area" autocapitalize="off" autocorrect="off"
+          input name="username" type="text" placeholder="Your username" class="input-Area" autocapitalize="off" autocorrect="off" value="#{flash[:username]}"
           br
           input name="password" type="password" class="input-Area" placeholder="Your password"
           br