Changes between Version 3 and Version 4 of GenshiTutorial

Timestamp:

Aug 29, 2007, 11:44:31 AM (16 years ago)

Author:

cmlenz

Comment:

First baby steps

GenshiTutorial

@@ -10 +10 @@
 
 The application is a stripped-down version of sites such as [http://reddit.com/ reddit] or [http://digg.com/ digg]: it lets users submit links to online articles they find interesting, and then lets other users vote on those stories and post comments.
+
+The project is kept as simple as possible, while still showing many of Genshi features and how to best use them:
+ * For persistence, we'll use native Python object serialization (via the `pickle` module), instead of an SQL database and an ORM.
+ * There's no authentication of any kind. Anyone can submit links, anyone can comment.
+
+== Prerequisites ==
+
+First, make sure you have !CherryPy 3.0.x installed, as well as recent versions of [http://formencode.org/ FormEncode], Genshi (obviously), and [http://pythonpaste.org/ Paste]. You can download and install those manually, or just use [http://peak.telecommunity.com/DevCenter/EasyInstall easy_install]:
+
+{{{
+$ easy_install CherryPy
+$ easy_install FormEncode
+$ easy_install Genshi
+$ easy_install Paste
+}}}
+
+== Getting Started ==
+
+Next, set up the basic !CherryPy application. Create a directory that should contain the application, and inside that directory create a Python package named `geddit` (basically a `geddit` directory containing an empty file called `__init__.py`. Inside that package, create a file called `controller.py` with the following content:
+
+{{{
+#!python
+#!/usr/bin/env python
+
+import os
+import pickle
+import sys
+
+import cherrypy
+from paste.evalexception.middleware import EvalException
+
+
+class Root(object):
+
+    def __init__(self, data):
+        self.data = data
+
+    @cherrypy.expose
+    def index(self):
+        return 'Geddit'
+
+
+def main(filename):
+    # load data from the pickle file, or initialize it to an empty list
+    if os.path.exists(filename):
+        fileobj = open(filename, 'rb')
+        try:
+            data = pickle.load(fileobj)
+        finally:
+            fileobj.close()
+    else:
+        data = []
+
+    # save data back to the pickle file when the server is stopped
+    def _save_data():
+        fileobj = open(filename, 'wb')
+        try:
+            pickle.dump(data, fileobj)
+        finally:
+            fileobj.close()
+    cherrypy.engine.on_stop_engine_list.append(_save_data)
+
+    # Some global configuration; note that this could be moved into a configuration file
+    cherrypy.config.update({
+        'request.throw_errors': True,
+        'tools.encode.on': True,
+        'tools.decode.on': True,
+        'tools.trailing_slash.on': True,
+        'tools.staticdir.root': os.path.abspath(os.path.dirname(__file__)),
+    })
+
+    # Initialize the application, and add EvalException for more helpful error messages
+    app = cherrypy.Application(Root(data))
+    app.wsgiapp.pipeline.append(('paste_exc', EvalException))
+    cherrypy.quickstart(app, '/', {
+        '/media': {
+            'tools.staticdir.on': True,
+            'tools.staticdir.dir': 'static'
+        }
+    })
+
+if __name__ == '__main__':
+    main(sys.argv[1])
+}}}
+
+Make that file executable, enter the tutorial directory in the terminal, and run:
+
+{{{
+$ geddit/controller.py geddit.db
+}}}
+
+You should see a log message pointing you to the URL where the application is being served, which is usually http://localhost:8080/. Visiting that page will respond with just the string “Geddit”, as that's what the `index()` method of the `Root` object returns.
+
+Note that we've configured !CherryPy to serve static files from the `geddit/media` directory. !CherryPy will complain that that directory does not exist, so create it, but leave it empty for now. We'll add static resources later on in the tutorial.
+
+== Rendering from a Genshi Template ==
+
+So far the code doesn't actually use Genshi, or even any kind of templating. Let's change that.