Vast improvements to validation, based on suggestions by Rick Copeland.

Error handlers are now internal redirects, rather than browser
redirects.

Added error handler middleware. This needs some configuration improvements.

Made the project template much better, with some CSS, and a Kajiki-based
layout.

pecan/__init__.py

@@ -1,7 +1,9 @@
 from paste.urlparser import StaticURLParser
 from paste.cascade import Cascade
+from weberror.errormiddleware import ErrorMiddleware
+from paste.recursive import RecursiveMiddleware
 
-from pecan import Pecan, request, response, override_template, redirect
+from pecan import Pecan, request, response, override_template, redirect, error_for
 from decorators import expose
 
 __all__ = [
@@ -9,8 +11,10 @@ __all__ = [
 ]
 
 
-def make_app(root, static_root=None, **kw):        
+def make_app(root, static_root=None, debug=False, errorcfg={}, **kw):
     app = Pecan(root, **kw)
+    app = RecursiveMiddleware(app)
+    app = ErrorMiddleware(app, debug=debug, **errorcfg)
     if static_root:
         app = Cascade([StaticURLParser(static_root), app])
     return app

pecan/pecan.py

@@ -5,6 +5,7 @@ from webob      import Request, Response, exc
 from threading  import local
 from itertools  import chain
 from formencode import Invalid
+from paste.recursive import ForwardRequestException
 
 try:
     from json import loads
@@ -19,6 +20,8 @@ def proxy(key):
     class ObjectProxy(object):
         def __getattr__(self, attr):
             obj = getattr(state, key)
+            if attr == 'validation_error':
+                return getattr(obj, attr, None)
             return getattr(obj, attr)
         def __setattr__(self, attr, value):
             obj = getattr(state, key)
@@ -37,6 +40,10 @@ def override_template(template):
 def redirect(location):
     raise exc.HTTPFound(location=location)
 
+def error_for(field):
+    if request.validation_error is None: return ''
+    return request.validation_error.error_dict.get(field, '')
+
 
 class Pecan(object):
     def __init__(self, root, 
@@ -122,6 +129,7 @@ class Pecan(object):
             controller.pecan['argspec']
         )
         if 'schema' in controller.pecan:
+            request.validation_error = None
             try:
                 params = self.validate(
                     controller.pecan['schema'], 
@@ -131,8 +139,7 @@ class Pecan(object):
             except Invalid, e:
                 request.validation_error = e
                 if controller.pecan['error_handler'] is not None:
-                    state.validation_error = e
+                    raise ForwardRequestException(controller.pecan['error_handler'])
-                    redirect(controller.pecan['error_handler'])
             if controller.pecan['validate_json']: params = dict(data=params)
         
         # get the result from the controller
@@ -147,7 +154,10 @@ class Pecan(object):
             renderer = self.renderers.get(self.default_renderer, self.template_path)
             if template == 'json':
                 renderer = self.renderers.get('json', self.template_path)
-            elif ':' in template:
+            else:
+                result['error_for'] = error_for
+                
+            if ':' in template:
                 renderer = self.renderers.get(template.split(':')[0], self.template_path)
                 template = template.split(':')[1]
             result = renderer.render(template, result)
@@ -168,12 +178,7 @@ class Pecan(object):
         state.request = Request(environ)
         state.response = Response()
         state.hooks = []
-        
+                
-        # handle validation errors from redirects
-        if hasattr(state, 'validation_error'):
-            state.request.validation_error = state.validation_error
-            del state.validation_error
-        
         # handle the request
         try:
             self.handle_request()

setup.py

@@ -21,7 +21,8 @@ class PyTest(Command):
 # determine requirements
 #
 requirements = [
-  "WebOb >= 0.9.8", 
+  "WebOb >= 1.0.0", 
+  "WebCore >= 1.0.0",
   "simplegeneric >= 0.7",
   "Genshi >= 0.6",
   "Kajiki >= 0.2.2",

templates/project/+egg+/controllers/root.py

@@ -1,6 +1,17 @@
-from pecan import expose
+from pecan import expose, request
+from formencode import Schema, validators as v
+
+
+class SampleForm(Schema):
+    name = v.String(not_empty=True)
+    age = v.Int(not_empty=True)
+
 
 class RootController(object):
     @expose('kajiki:index.html')
-    def index(self, name='World'):
+    def index(self, name='', age=''):
-        return dict(name=name)
+        return dict(errors=request.validation_error, name=name, age=age)
+    
+    @expose('kajiki:success.html', schema=SampleForm(), error_handler='index')
+    def handle_form(self, name, age):
+        return dict(name=name, age=age)

templates/project/+egg+/templates/index.html

@@ -1,8 +1,44 @@
-<html>
+<html py:extends="layout.html">
   <head>
-    <title>Hello, ${name}</title>
+    <title py:block="title">Welcome to Pecan!</title>
   </head>
-  <body>
+  <body py:block="body">
-    <h1>Hello, ${name}!</h1>
+    <header>
+      <h1>Welcome to Pecan</h1>
+    </header>
+    <p>This is the default Pecan project, which includes:</p>
+    
+    <ul>
+      <li>The ability to serve static files.</li>
+      <li>Templating using the <a href="http://kajiki.pythonisito.com/">Kajiki template engine</a>.</li>
+      <li>Built-in error management using <a href="http://pypi.python.org/pypi/WebError">WebError</a>.</li>
+    </ul>
+    
+    <p>
+      Note that most functionality is enabled/disabled in your <code>start.py</code>,
+      which can be edited to suit your needs, and to add additional WSGI middleware.
+    </p>
+    
+    <p>
+      To get an idea of how to develop applications with Pecan, 
+      here is a simple form:
+    </p>
+    
+    <form method="POST" action="/handle_form" class="${'invalid' if errors else ''}">
+      <table>
+        <tr>
+          <td><label for="name">What is your name</label></td>
+          <td><input name="name" value="${name}" class="${'invalid' if error_for('name') else ''}" /></td>
+          <td py:if="errors">${error_for('name')}</td>
+        </tr>
+        <tr>
+          <td><label for="age">How old are you?</label></td>
+          <td><input name="age" value="${age}" class="${'invalid' if error_for('age') else ''}" /></td>
+          <td py:if="errors">${error_for('age')}</td>
+        </tr>
+      </table>
+      
+      <input type="submit" />
+    </form>
   </body>
 </html>

templates/project/+egg+/templates/layout.html

@@ -0,0 +1,13 @@
+<html>
+  <head>
+    <title py:block="title">Default Title</title>
+    <py:block name="style">
+      <link rel="stylesheet" type="text/css" media="screen" href="/css/style.css" />
+    </py:block>
+    <py:block name="javascript" py:strip="True">
+      <script language="text/javascript" src="/javascript/shared.js" />
+    </py:block>
+  </head>
+  <body py:block="body">
+  </body>
+</html>

templates/project/+egg+/templates/success.html

@@ -0,0 +1,11 @@
+<html py:extends="layout.html">
+  <head>
+    <title py:block="title">Success!</title>
+  </head>
+  <body py:block="body">
+    <header>
+      <h1>Success!</h1>
+    </header>
+    <p>Your form submission was successful! Thanks, ${name}!</p>
+  </body>
+</html>

templates/project/public/css/style.css

@@ -0,0 +1,39 @@
+body {
+  background: #311F00;
+  color: white;
+  font-family: 'Helvetica Neue', 'Helvetica', 'Verdana', sans-serif;
+  font-size: 1.25em;
+  padding: 1em 2em;
+}
+
+a {
+  color: #FAFF78;
+  text-decoration: none;
+}
+
+a:hover {
+  text-decoration: underline;
+}
+
+form {
+  margin: 0 1em;
+  padding: 1em;
+  border: 5px transparent;
+}
+
+form.invalid {
+  border: 5px solid FAFF78;
+}
+
+input.invalid {
+  background: #FAFF78;
+}
+
+header {
+  text-align: center;
+}
+
+h1, h2, h3, h4, h5, h6 {
+  font-family: 'Futura-CondensedExtraBold', 'Futura', 'Helvetica', sans-serif;
+  text-transform: uppercase;
+}

templates/project/start.py_tmpl

@@ -5,7 +5,8 @@ if __name__ == '__main__':
     app = make_app(
         RootController(), 
         static_root='public',
-        template_path='${egg}/templates'
+        template_path='${egg}/templates',
+        debug=True
     )
 
     print 'Serving on http://0.0.0.0:8080'    

tests/test_validation.py

@@ -1,4 +1,4 @@
-from pecan import Pecan, expose, request, response
+from pecan import make_app, expose, request, response
 from webtest import TestApp
 
 from formencode import validators, Schema
@@ -45,7 +45,7 @@ class TestValidation(object):
                 return 'Success!'
 
         # test form submissions
-        app = TestApp(Pecan(RootController()))
+        app = TestApp(make_app(RootController()))
         r = app.post('/', dict(
             first_name='Jonathan',
             last_name='LaCour',
@@ -85,6 +85,11 @@ class TestValidation(object):
             ]
         
         class RootController(object):
+            @expose()
+            def errors(self, *args, **kwargs):
+                assert request.validation_error is not None
+                return 'There was an error!'
+            
             @expose(schema=RegistrationSchema())
             def index(self, first_name, 
                             last_name, 
@@ -116,15 +121,10 @@ class TestValidation(object):
             def json_with_handler(self, data):
                 assert request.validation_error is not None
                 return 'Success!'
-            
-            @expose()
-            def errors(self, *args, **kwargs):
-                assert request.validation_error is not None
-                return 'There was an error!'
                 
 
         # test without error handler
-        app = TestApp(Pecan(RootController()))
+        app = TestApp(make_app(RootController()))
         r = app.post('/', dict(
             first_name='Jonathan',
             last_name='LaCour',
@@ -138,7 +138,7 @@ class TestValidation(object):
         assert r.body == 'Success!'
         
         # test with error handler
-        app = TestApp(Pecan(RootController()))
+        app = TestApp(make_app(RootController()))
         r = app.post('/with_handler', dict(
             first_name='Jonathan',
             last_name='LaCour',
@@ -148,8 +148,6 @@ class TestValidation(object):
             password_confirm='654321',
             age='31'
         ))
-        assert r.status_int == 302
-        r = r.follow()
         assert r.status_int == 200
         assert r.body == 'There was an error!'
         
@@ -176,7 +174,5 @@ class TestValidation(object):
             password_confirm='654321',
             age='31'
         )), [('content-type', 'application/json')])
-        assert r.status_int == 302
-        r = r.follow()
         assert r.status_int == 200
         assert r.body == 'There was an error!'