pycms/pycms-documentation.txt at master · flberger/pycms · GitHub

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Documentation for pycms
=======================

pycms is a lightweight web content management system.

Import
------

To use the pycms API, first import the pycms module.

    >>> import pycms
    >>>


Creating a new instance
-----------------------

An instance represents a hierarchy of pages, along with templates.
It is initialised with the path to a root directory. This is an
ordinary directory, with a subdirectory for templates.

    >>> instance = pycms.Instance("pycmsroot")
    >>>


Initialising files and directories
----------------------------------

pycms needs a working environment to store the CMS contents in.

For a new pycms instance, this working environment must be created
before pycms can be used. Otherwise an exception will be raised when
trying to run pycms.

    >>> instance.serve(test = True)
    Traceback (most recent call last):
    ...
    RuntimeError: Working environment directory 'pycmsroot' not found. Did you run pycms.envinit("pycmsroot")?
    >>>

The 'test' flag will terminate pycms after a short while, for
automated testing.

The envinit() method will take care of creating the environment.

    >>> instance.envinit()
    >>>

There now is a basic environment to work with. Let's take a look:

    >>> import glob
    >>> files = glob.glob("pycmsroot/*")
    >>> files.sort()
    >>> files
    ['pycmsroot/_templates', 'pycmsroot/_uri_template_map.json', 'pycmsroot/index.html', 'pycmsroot/static']
    >>> glob.glob("pycmsroot/_templates/*")
    ['pycmsroot/_templates/index_template.html']
    >>>


Adding templates
----------------

pycms templates are simple HTML files with placeholder lines.

To add a template, drop it into the '_templates' folder.

    >>> with open("pycmsroot/_templates/new_template.html", "wt") as templatefile:
    ...     templatefile.write('<!DOCTYPE html>\n<html>\n<meta charset="utf-8"/>\n<head>\n    <title>\n        TITLE\n    </title>\n</head>\n<body>\n    CONTENT\n</body>\n</html>')
    ...
    135
    >>> files = glob.glob("pycmsroot/_templates/*")
    >>> files.sort()
    >>> files
    ['pycmsroot/_templates/index_template.html', 'pycmsroot/_templates/new_template.html']
    >>>


Creating pages based on templates
---------------------------------

pycms pages are tied to an URI and based on a template. To create a
new page, all of these must be given.

    >>> instance.create_page("/test", "new_template.html")
    >>>

Any trailing URI slash will be stripped before creating the page.
"/test/" and "/test" refer to the same object, though.

    >>> instance.create_page("/test/", "new_template.html")
    Traceback (most recent call last):
    ...
    RuntimeError: URI "/test/" can not be created because "pycmsroot/test" already exists.
    >>>

pycms uses the traditional index page convention to represent contents
on disk. The command will create a new directory and HTML file in the
working environment.

    >>> glob.glob("pycmsroot/test/*")
    ['pycmsroot/test/index.html']
    >>> with open("pycmsroot/test/index.html") as f:
    ...     print(f.read())
    <!DOCTYPE html>
    <html>
    <meta charset="utf-8"/>
    <head>
        <title>
            TITLE
        </title>
    </head>
    <body>
        CONTENT
    </body>
    </html>
    >>>

It also registers the URI in the template-URI map.

    >>> with open("pycmsroot/_uri_template_map.json") as f:
    ...     print(f.read())
    {"/": "index_template.html", "/test": "new_template.html"}
    >>>


Editing page content
--------------------

You can edit page content in the pycms instance's working environment
straight away with your favourite HTML editor.

pycms expects that you only change the placeholder elements of the
respective page template. Anything concerning the templates will
likely affect other pages as well, so you are expected to change
the template in that case -- see the next section for this.

    >>> with open("pycmsroot/test/index.html", "rt") as f:
    ...    html = f.read()
    ...
    >>> html = html.replace("TITLE", "My first pycms page")
    >>> html = html.replace("CONTENT", '<h1>My fist pycms page</h1>\n<p>This is my first pycms page.</p>')
    >>> with open("pycmsroot/test/index.html", "wt") as f:
    ...     f.write(html)
    ...
    205
    >>> with open("pycmsroot/test/index.html") as f:
    ...     print(f.read())
    <!DOCTYPE html>
    <html>
    <meta charset="utf-8"/>
    <head>
        <title>
            My first pycms page
        </title>
    </head>
    <body>
        <h1>My fist pycms page</h1>
    <p>This is my first pycms page.</p>
    </body>
    </html>
    >>>


Editing templates and applying changes
--------------------------------------

pycms templates make it very convenient to change the style, layout
and repeating content on several pages.

pycms has to be able to track the changes you are about to make to
a template. So you first have to signal that you are going to edit
it.

    >>> instance.edit_template("new_template.html")
    >>>

This will create a backup of the current template, with the suffix
'.old' added.

    >>> files = glob.glob("pycmsroot/_templates/*")
    >>> files.sort()
    >>> files
    ['pycmsroot/_templates/index_template.html', 'pycmsroot/_templates/new_template.html', 'pycmsroot/_templates/new_template.html.old']
    >>>

You can now go ahead and edit the original template.

    >>> with open("pycmsroot/_templates/new_template.html", "wt") as templatefile:
    ...     templatefile.write('<!DOCTYPE html>\n<html>\n<meta charset="utf-8"/>\n<head>\n    <title>\n        TITLE\n    </title>\n</head>\n<body>\n<hr>\n    CONTENT\n<hr>\n</body>\n</html>')
    ...
    145

After that, notify pycms that you are done updating the template. This
will apply pending changes to all pages using the template, and delete
any preceding versions of the template.

    >>> instance.update()
    >>> with open("pycmsroot/test/index.html") as f:
    ...     print(f.read())
    <!DOCTYPE html>
    <html>
    <meta charset="utf-8"/>
    <head>
        <title>
            My first pycms page
        </title>
    </head>
    <body>
    <hr>
        <h1>My fist pycms page</h1>
    <p>This is my first pycms page.</p>
    <hr>
    </body>
    </html>
    >>> files = glob.glob("pycmsroot/_templates/*")
    >>> files.sort()
    >>> files
    ['pycmsroot/_templates/index_template.html', 'pycmsroot/_templates/new_template.html']
    >>>


Removing a page
---------------

Removing a page is simple:

    >>> instance.remove_page("/test")
    >>>

Again, a trailing slash will be stripped:

    >>> instance.remove_page("/test/")
    Traceback (most recent call last):
    ...
    RuntimeError: URI "/test/" can not be removed because "pycmsroot/test" does not exist.
    >>>

On disk, the directory and the index page will be removed:

    >>> files = glob.glob("pycmsroot/*")
    >>> files.sort()
    >>> files
    ['pycmsroot/_templates', 'pycmsroot/_uri_template_map.json', 'pycmsroot/index.html', 'pycmsroot/static']

The URI will also be removed from the template-URI map.

    >>> with open("pycmsroot/_uri_template_map.json") as f:
    ...     print(f.read())
    {"/": "index_template.html"}
    >>>

However the template used persists:

    >>> files = glob.glob("pycmsroot/_templates/*")
    >>> files.sort()
    >>> files
    ['pycmsroot/_templates/index_template.html', 'pycmsroot/_templates/new_template.html']
    >>>

Removing the root URI "/" will remove the index page only, not the
root directory.

    >>> instance.remove_page("/")
    >>> with open("pycmsroot/_uri_template_map.json") as f:
    ...     print(f.read())
    {}
    >>> files = glob.glob("pycmsroot/*")
    >>> files.sort()
    >>> files
    ['pycmsroot/_templates', 'pycmsroot/_uri_template_map.json', 'pycmsroot/static']
    >>>

This of course is a state one would not want to keep.

    >>> instance.create_page("/", "index_template.html")
    >>>


Running the pycms web server
----------------------------

Once there is a working environment, pycms can serve content from it.

The serve() method runs an HTTP server.

    >>> instance.serve(test = True)
    >>>


pycms data representation
-------------------------

When preparing to serve, pymcs parses the working environment and
creates an internal data structure. This is done by the
pycms.envparse() method. This method expects the path to the
working environment and a pycms.CMS instance as input. For
demonstration purposes, we will use a dummy object here, bypassing
pycms.CMS.__init__().

    >>> class DummyCMS:
    ...     pass
    ...
    >>> dummy_cms = DummyCMS()
    >>> dummy_cms.__dict__["__class__"] = pycms.CMS
    >>> pycms.envparse("pycmsroot", dummy_cms)
    >>>

The CMS instance will be populated by the parsing results. In this
case, only the single root page is created, which can be obtained by
calling the CMS instance as a method. This yields the default page
created by pycms.envinit() above.

    >>> dummy_cms()
    '<!DOCTYPE html>\n    <html>\n    <meta charset="utf-8"/>\n    <head>\n        <title>\n            TITLE\n        </title>\n    </head>\n    <body>\n    CONTENT\n    </body>\n    </html>\n    '
    >>>


Static content and special directories
--------------------------------------

There is a folder 'static' below the pycms root directory where you
can store static content. It can neither be removed nor re-created.

    >>> instance.remove_page("/static")
    Traceback (most recent call last):
    ...
    RuntimeError: "/static/" is a special URI and can not be removed.
    >>>

    >>> instance.create_page("/static", "new_template.html")
    Traceback (most recent call last):
    ...
    RuntimeError: "/static/" is a special URI and can not be re-created.
    >>>

The same goes for the '_templates' folder.

    >>> instance.remove_page("/_templates")
    Traceback (most recent call last):
    ...
    RuntimeError: "/_templates/" is a special URI and can not be removed.
    >>>

    >>> instance.create_page("/_templates", "new_template.html")
    Traceback (most recent call last):
    ...
    RuntimeError: "/_templates/" is a special URI and can not be re-created.
    >>>


Deleting a pycms environment
----------------------------

To do this, simply delete the project folder.

    >>> import shutil
    >>> shutil.rmtree("pycmsroot")
    >>>


Command line interface
----------------------

To make pycms serve content over an HTTP socket, issue the command

    python pycms.py htmlroot

on the command line. `htmlroot` is a directory containing the data to serve
from and to save to. If written as above, pycms assumes it to be a local
subdirectory. You can also give full qualified paths as `/home/user/htmlroot`
or `C:\htmlroot\`, depending on your operatings system.


Helper Classes and Methods
--------------------------

pycms contains various helpers under the hood to perform its work.


### LineReplacement

The LineReplacement class is being used to compute differences between
templates and actual pages. It utilises knowledge about how pycms
templates work.

    >>> source = """<html>
    ... <head><title>Test Template</title></head>
    ... <body>
    ... REPLACE_THIS
    ... </body>
    ... </html>"""
    >>> result = """<html>
    ... <head><title>Test Template</title></head>
    ... <body>
    ...     <div>
    ...         <p>Replaced!</p>
    ...     </div>
    ... </body>
    ... </html>"""
    >>> lp = pycms.LineReplacement(source, result)
    >>> lp.replacements
    {'REPLACE_THIS': '<div>\n        <p>Replaced!</p>\n    </div>'}
    >>>

It also has a method to apply the found replacements to new strings.

    >>> original = """<html>
    ... <head><title>Another Template</title></head>
    ... <body>
    ...   <div>
    ... REPLACE_THIS
    ...   </div>
    ... </body>
    ... </html>"""
    >>> lp.replace(original)
    '<html>\n<head><title>Another Template</title></head>\n<body>\n  <div>\n<div>\n        <p>Replaced!</p>\n    </div>\n  </div>\n</body>\n</html>'
    >>>