Changes between Version 1 and Version 2 of TemplatePitfalls

Timestamp:

Aug 20, 2005, 10:23:32 PM (20 years ago)

Author:

garthk

Comment:

--

TemplatePitfalls

@@ -1 @@
-describe TemplatePitfalls here
+Here's how to dodge some of the more obvious template pitfalls: 
 
 
-
-----
+== Debugging ==
 
 Not a pitfall, but a tip:
@@ -9 +8 @@
 Use {% debug %} in a template block if you want to know what is defined and can be used in a template.
 
-Any tips on how to format the debug output nicer?
+The debug output is pretty ugly unless you look at it through View Source. 
 
-----
+== Anonymity ==
+
+{{{user.is_anonymous}}} is a method, not an attribute, which makes it hard to test against in a template. Set your own context variable {{{is_anonymous}}}, instead. 
+
+== Context variables and template inheritance ==
+
+To solve ''Anonymity'' above, it's handy to define a method each view can call to fill in its {{{Context}}} with the right variables. If you're inheriting templates, you should also do the same with the method. I've ended up with an {{{app_vars}}} method in each app's views module which calls {{{site_vars}}} in the site. 
+
+{{{site_vars}}} goes in {{{sitename/views/sitename.py}}} if you're trying to match the default shape of the application namespace, or in {{{sitename/views.py}}} if you're flattening it: 
+
+{{{
+def site_vars(request, **kwargs): 
+    """Determine context variables for the site's base template."""
+    user = request.user
+    is_anonymous = user.is_anonymous()
+    if is_anonymous: 
+        username = name = '(anonymous)'
+    else: 
+        username = user.username
+        name = user.get_full_name()
+        if not name: 
+            name = username
+    vars = {
+        'is_anonymous': is_anonymous,
+        'name': name,
+        'username': username,
+    }
+    vars.update(kwargs)
+    return vars
+}}}
+
+A custom version of {{{app_vars}}} goes in each {{{sitename/apps/appname/views/appname.py}}} (or, if you're flattening the namespace, {{{sitename/apps/appname/views.py}}}):
+
+{{{
+def app_vars(request, **kwargs): 
+    """Determine context variables for the application and site base templates."""
+    vars = {} # set your app variables here
+    vars.update(site_vars(request, **kwargs))
+    return vars
+}}}
+
+The keyword arguments let you define additional useful variables for your page without having to further manipulate the dictionary: just keep piling on the arguments to {{{app_vars}}}. Let's say your base template likes to have a {{{title}}} variable available to it: 
+
+{{{
+def index(request): 
+    """View the appname index."""
+
+    # Customise the app variables the hard way
+    vars = app_vars(request)
+    vars['title'] = "Index" 
+
+    # Or, the easy way
+    vars = app_vars(request, title="Index")
+
+    # Load the template, construct the context, and render one against the other: 
+    t = template_loader.get_template('appname_index')
+    c = Context(request, vars)
+    return HttpResponse(t.render(c))
+}}}