How can you split templates in mako in several files/directories?

Question

I am trying to understand how to split a project which uses Mako and CherryPy in several directories. I have prepared the following directory structure:

[FOLDER] /home/user/myapp
         |- main.py
         |- app.config
         |- server.config
[FOLDER] /home/user/myapp/templates
[FOLDER] /home/user/myapp/templates/base
         |- index.html
         |- sidebar_menu.html
[FOLDER] /home/user/myapp/config
         |- templates.py

In /home/user/myapp/templates there will be the different templates organised in directories.

Under /home/user/myapp/config I have the following file: templates.py with the following code:

# -*- coding: utf-8 -*-

import mako.template
import mako.lookup

# Templates
templates_lookup = mako.lookup.TemplateLookup(
    directories=[
        '/templates',
        '/templates/base',
    ],
    module_directory='/tmp/mako_modules',
    input_encoding='utf-8', 
    output_encoding='utf-8', 
    encoding_errors='replace'
)

def serve_template(templatename, **kwargs):
    mytemplate = templates_lookup.get_template(templatename)
    print(mytemplate.render(**kwargs))

Under /home/user/myapp there will be the following main.py file:

# -*- coding: utf-8 -*-

import os
import cherrypy
import mako.template
import mako.lookup
import config.templates

# Main Page
class Index(object):
    @cherrypy.expose
    def index(self): 
        t = config.templates.serve_template('index.html')
        print(t)
        return t

cherrypy.config.update("server.config")
cherrypy.tree.mount(Index(), '/', "app.config")
cherrypy.engine.start()

When I launch the application and access / I get the following message:

500 Internal Server Error

The server encountered an unexpected condition which prevented it from fulfilling the request.

Traceback (most recent call last):
  File "C:\Python37\lib\site-packages\mako\lookup.py", line 247, in get_template
    return self._check(uri, self._collection[uri])
KeyError: 'index.html'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "C:\Python37\lib\site-packages\cherrypy\_cprequest.py", line 628, in respond
    self._do_respond(path_info)
  File "C:\Python37\lib\site-packages\cherrypy\_cprequest.py", line 687, in _do_respond
    response.body = self.handler()
  File "C:\Python37\lib\site-packages\cherrypy\lib\encoding.py", line 219, in __call__
    self.body = self.oldhandler(*args, **kwargs)
  File "C:\Python37\lib\site-packages\cherrypy\_cpdispatch.py", line 54, in __call__
    return self.callable(*self.args, **self.kwargs)
  File ".....\myapp\main.py", line 18, in index
    t = config.templates.serve_template('index.html')
  File ".....\myapp\config\templates.py", line 19, in serve_template
    mytemplate = templates_lookup.get_template(templatename)
  File "C:\Python37\lib\site-packages\mako\lookup.py", line 261, in get_template
    "Cant locate template for uri %r" % uri)
mako.exceptions.TopLevelLookupException: Cant locate template for uri 'index.html'

Powered by CherryPy 18.1.0 

So basically it seems that Mako can not locate index.html despite we are providing the directories. I guess I am not understanding how Mako uses in the lookup.

Note: program is actually run in Windows, I used UNIX file structure above just to make the file structure easier to read.

Python 3.7.2
CherryPy 18.1.0
Mako 1.0.7

Answer 1

You state your directory structure is /home/user/myapp/templates

but you're telling Mako to look in /templates

Maybe change code to: directories=[ '/home/user/myapp/templates', '/home/user/myapp/templates/base', ],

Answer 2

I usually split the templates into per-page templates and global templates example:

src/
├── constants.py
├── home
│   └── user
│       └── myapp
│           ├── app.config
│           ├── main.mako
│           ├── main.py
│           └── server.config
└── templates
    ├── e404.mako
    ├── e500.mako
    ├── footer.mako
    └── header.mako

in this case, i'll always import a global file with the lookup dir

# src/constants.py
from mako.lookup import TemplateLookup
mylookup = TemplateLookup(directories=['.', 'dir/to/src/templates/'])

# home/user/myapp/main.py
from src.constants import mylookup

def main():
   if i_have_errer:
       template = mylookup.get_template('e500.mako')
   else:
       template = mylookup.get_template('main.mako')

   return template.render_unicode()

the '.' will lookup first in current directory the templates/ will lookup the global src/templates/ for a more generic templates