more doc

[roundup.git] / doc / customizing.txt

===================
Customising Roundup
===================

:Version: $Revision: 1.24 $

.. This document borrows from the ZopeBook section on ZPT. The original is at:
   http://www.zope.org/Documentation/Books/ZopeBook/current/ZPT.stx

.. contents::


What You Can Do
---------------

Customisation of Roundup can take one of five forms:

1. `tracker configuration`_ file changes
2. database, or `tracker schema`_ changes
3. "definition" class `database content`_ changes
4. behavioural changes, through detectors_
5. `access controls`_

The third case is special because it takes two distinctly different forms
depending upon whether the tracker has been initialised or not. The other two
may be done at any time, before or after tracker initialisation. Yes, this
includes adding or removing properties from classes.


Trackers in a Nutshell
----------------------

Trackers have the following structure:

+-------------------+--------------------------------------------------------+
|config.py          |Holds the basic `tracker configuration`_                |
+-------------------+--------------------------------------------------------+
|dbinit.py          |Holds the `tracker schema`_                             |
+-------------------+--------------------------------------------------------+
|interfaces.py      |Defines the Web and E-Mail interfaces for the tracker   |
+-------------------+--------------------------------------------------------+
|select_db.py       |Selects the database back-end for the tracker           |
+-------------------+--------------------------------------------------------+
|db/                |Holds the tracker's database                            |
+-------------------+--------------------------------------------------------+
|db/files/          |Holds the tracker's upload files and messages           |
+-------------------+--------------------------------------------------------+
|detectors/         |Auditors and reactors for this tracker                  |
+-------------------+--------------------------------------------------------+
|html/              |Web interface templates, images and style sheets        |
+-------------------+--------------------------------------------------------+

Tracker Configuration
---------------------

The config.py located in your tracker home contains the basic
configuration for the web and e-mail components of roundup's interfaces. This
file is a Python module. The configuration variables available are:

**INSTANCE_HOME** - ``os.path.split(__file__)[0]``
 The tracker home directory. The above default code will automatically
 determine the tracker home for you.

**MAILHOST** - ``'localhost'``
 The SMTP mail host that roundup will use to send e-mail.

**MAIL_DOMAIN** - ``'your.tracker.email.domain.example'``
 The domain name used for email addresses.

**DATABASE** - ``os.path.join(INSTANCE_HOME, 'db')``
 This is the directory that the database is going to be stored in. By default
 it is in the tracker home.

**TEMPLATES** - ``os.path.join(INSTANCE_HOME, 'html')``
 This is the directory that the HTML templates reside in. By default they are
 in the tracker home.

**INSTANCE_NAME** - ``'Roundup issue tracker'``
 A descriptive name for your roundup tracker. This is sent out in e-mails and
 appears in the heading of CGI pages.

**ISSUE_TRACKER_EMAIL** - ``'issue_tracker@%s'%MAIL_DOMAIN``
 The email address that e-mail sent to roundup should go to. Think of it as the
 tracker's personal e-mail address.

**ISSUE_TRACKER_WEB** - ``'http://your.tracker.url.example/'``
 The web address that the tracker is viewable at. This will be included in
 information sent to users of the tracker.

**ADMIN_EMAIL** - ``'roundup-admin@%s'%MAIL_DOMAIN``
 The email address that roundup will complain to if it runs into trouble.

**MESSAGES_TO_AUTHOR** - ``'yes'`` or``'no'``
 Send nosy messages to the author of the message.

**ADD_AUTHOR_TO_NOSY** - ``'new'``, ``'yes'`` or ``'no'``
 Does the author of a message get placed on the nosy list automatically?
 If ``'new'`` is used, then the author will only be added when a message
 creates a new issue. If ``'yes'``, then the author will be added on followups
 too. If ``'no'``, they're never added to the nosy.

**ADD_RECIPIENTS_TO_NOSY** - ``'new'``, ``'yes'`` or ``'no'``
 Do the recipients (To:, Cc:) of a message get placed on the nosy list?
 If ``'new'`` is used, then the recipients will only be added when a message
 creates a new issue. If ``'yes'``, then the recipients will be added on
 followups too. If ``'no'``, they're never added to the nosy.

**EMAIL_SIGNATURE_POSITION** - ``'top'``, ``'bottom'`` or ``'none'``
 Where to place the email signature in messages that Roundup generates.

**EMAIL_KEEP_QUOTED_TEXT** - ``'yes'`` or ``'no'``
 Keep email citations. Citations are the part of e-mail which the sender has
 quoted in their reply to previous e-mail.

**EMAIL_LEAVE_BODY_UNCHANGED** - ``'no'``
 Preserve the email body as is. Enabiling this will cause the entire message
 body to be stored, including all citations and signatures. It should be
 either ``'yes'`` or ``'no'``.

**MAIL_DEFAULT_CLASS** - ``'issue'`` or ``''``
 Default class to use in the mailgw if one isn't supplied in email
 subjects. To disable, comment out the variable below or leave it blank.

The default config.py is given below - as you
can see, the MAIL_DOMAIN must be edited before any interaction with the
tracker is attempted.::

    # roundup home is this package's directory
    INSTANCE_HOME=os.path.split(__file__)[0]

    # The SMTP mail host that roundup will use to send mail
    MAILHOST = 'localhost'

    # The domain name used for email addresses.
    MAIL_DOMAIN = 'your.tracker.email.domain.example'

    # This is the directory that the database is going to be stored in
    DATABASE = os.path.join(INSTANCE_HOME, 'db')

    # This is the directory that the HTML templates reside in
    TEMPLATES = os.path.join(INSTANCE_HOME, 'html')

    # A descriptive name for your roundup tracker
    INSTANCE_NAME = 'Roundup issue tracker'

    # The email address that mail to roundup should go to
    ISSUE_TRACKER_EMAIL = 'issue_tracker@%s'%MAIL_DOMAIN

    # The web address that the tracker is viewable at
    ISSUE_TRACKER_WEB = 'http://your.tracker.url.example/'

    # The email address that roundup will complain to if it runs into trouble
    ADMIN_EMAIL = 'roundup-admin@%s'%MAIL_DOMAIN

    # Somewhere for roundup to log stuff internally sent to stdout or stderr
    LOG = os.path.join(INSTANCE_HOME, 'roundup.log')

    # Send nosy messages to the author of the message
    MESSAGES_TO_AUTHOR = 'no'           # either 'yes' or 'no'

    # Does the author of a message get placed on the nosy list automatically?
    # If 'new' is used, then the author will only be added when a message
    # creates a new issue. If 'yes', then the author will be added on followups
    # too. If 'no', they're never added to the nosy.
    ADD_AUTHOR_TO_NOSY = 'new'          # one of 'yes', 'no', 'new'

    # Do the recipients (To:, Cc:) of a message get placed on the nosy list?
    # If 'new' is used, then the recipients will only be added when a message
    # creates a new issue. If 'yes', then the recipients will be added on followups
    # too. If 'no', they're never added to the nosy.
    ADD_RECIPIENTS_TO_NOSY = 'new'      # either 'yes', 'no', 'new'

    # Where to place the email signature
    EMAIL_SIGNATURE_POSITION = 'bottom' # one of 'top', 'bottom', 'none'

    # Keep email citations
    EMAIL_KEEP_QUOTED_TEXT = 'no'       # either 'yes' or 'no'

    # Preserve the email body as is
    EMAIL_LEAVE_BODY_UNCHANGED = 'no'   # either 'yes' or 'no'

    # Default class to use in the mailgw if one isn't supplied in email
    # subjects. To disable, comment out the variable below or leave it blank.
    # Examples:
    MAIL_DEFAULT_CLASS = 'issue'   # use "issue" class by default
    #MAIL_DEFAULT_CLASS = ''        # disable (or just comment the var out)

Tracker Schema
--------------

Note: if you modify the schema, you'll most likely need to edit the
      `web interface`_ HTML template files and `detectors`_ to reflect
      your changes.

A tracker schema defines what data is stored in the tracker's database.
The
schemas shipped with Roundup turn it into a typical software bug tracker or
help desk.

XXX make sure we ship the help desk

Schemas are defined using Python code in the ``dbinit.py`` module of your
tracker. The "classic" schema looks like this::

    pri = Class(db, "priority", name=String(), order=String())
    pri.setkey("name")
    pri.create(name="critical", order="1")
    pri.create(name="urgent", order="2")
    pri.create(name="bug", order="3")
    pri.create(name="feature", order="4")
    pri.create(name="wish", order="5")

    stat = Class(db, "status", name=String(), order=String())
    stat.setkey("name")
    stat.create(name="unread", order="1")
    stat.create(name="deferred", order="2")
    stat.create(name="chatting", order="3")
    stat.create(name="need-eg", order="4")
    stat.create(name="in-progress", order="5")
    stat.create(name="testing", order="6")
    stat.create(name="done-cbb", order="7")
    stat.create(name="resolved", order="8")

    keyword = Class(db, "keyword", name=String())
    keyword.setkey("name")

    user = Class(db, "user", username=String(), password=String(),
        address=String(), realname=String(), phone=String(),
        organisation=String())
    user.setkey("username")
    user.create(username="admin", password=adminpw,
        address=config.ADMIN_EMAIL)

    msg = FileClass(db, "msg", author=Link("user"), recipients=Multilink
        ("user"), date=Date(), summary=String(), files=Multilink("file"))

    file = FileClass(db, "file", name=String(), type=String())

    issue = IssueClass(db, "issue", assignedto=Link("user"),
        topic=Multilink("keyword"), priority=Link("priority"), status=Link
        ("status"))
    issue.setkey('title')

XXX security definitions

Classes and Properties - creating a new information store
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

In the tracker above, we've defined 7 classes of information:

  priority
      Defines the possible levels of urgency for issues.

  status
      Defines the possible states of processing the issue may be in.

  keyword
      Initially empty, will hold keywords useful for searching issues.

  user
      Initially holding the "admin" user, will eventually have an entry for all
      users using roundup.

  msg
      Initially empty, will all e-mail messages sent to or generated by
      roundup.

  file
      Initially empty, will all files attached to issues.

  issue
      Initially empty, this is where the issue information is stored.

We define the "priority" and "status" classes to allow two things: reduction in
the amount of information stored on the issue and more powerful, accurate
searching of issues by priority and status. By only requiring a link on the
issue (which is stored as a single number) we reduce the chance that someone
mis-types a priority or status - or simply makes a new one up.

Class and Items
:::::::::::::::

A Class defines a particular class (or type) of data that will be stored in the
database. A class comprises one or more properties, which given the information
about the class items.
The actual data entered into the database, using class.create() are called
items. They have a special immutable property called id. We sometimes refer to
this as the itemid.

Properties
::::::::::

A Class is comprised of one or more properties of the following types:

* String properties are for storing arbitrary-length strings.
* Password properties are for storing encoded arbitrary-length strings. The
  default encoding is defined on the roundup.password.Password class.
* Date properties store date-and-time stamps. Their values are Timestamp
  objects.
* Number properties store numeric values.
* Boolean properties store on/off, yes/no, true/false values.
* A Link property refers to a single other item selected from a specified
  class. The class is part of the property; the value is an integer, the id
  of the chosen item.
* A Multilink property refers to possibly many items in a specified class.
  The value is a list of integers.

FileClass
:::::::::

FileClasses save their "content" attribute off in a separate file from the rest
of the database. This reduces the number of large entries in the database,
which generally makes databases more efficient, and also allows us to use
command-line tools to operate on the files. They are stored in the files sub-
directory of the db directory in your tracker.

IssueClass
::::::::::

IssueClasses automatically include the "messages", "files", "nosy", and
"superseder" properties.
The messages and files properties list the links to the messages and files
related to the issue. The nosy property is a list of links to users who wish to
be informed of changes to the issue - they get "CC'ed" e-mails when messages
are sent to or generated by the issue. The nosy reactor (in the detectors
directory) handles this action. The superceder link indicates an issue which
has superceded this one.
They also have the dynamically generated "creation", "activity" and "creator"
properties.
The value of the "creation" property is the date when an item was created, and
the value of the "activity" property is the date when any property on the item
was last edited (equivalently, these are the dates on the first and last
records in the item's journal). The "creator" property holds a link to the user
that created the issue.

setkey(property)
::::::::::::::::

Select a String property of the class to be the key property. The key property
muse be unique, and allows references to the items in the class by the content
of the key property. That is, we can refer to users by their username, e.g.
let's say that there's an issue in roundup, issue 23. There's also a user,
richard who happens to be user 2. To assign an issue to him, we could do either
of::

     roundup-admin set issue assignedto=2

or::

     roundup-admin set issue assignedto=richard

Note, the same thing can be done in the web and e-mail interfaces.

create(information)
:::::::::::::::::::

Create an item in the database. This is generally used to create items in the
"definitional" classes like "priority" and "status".


Examples of adding to your schema
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

TODO


Detectors - adding behaviour to your tracker
--------------------------------------------
.. _detectors:

The detectors in your tracker fire before (*auditors*) and after (*reactors*)
changes to the contents of your database. They are Python modules that sit in
your tracker's ``detectors`` directory. You will have some installed by
default - have a look. You can write new detectors or modify the existing
ones. The existing detectors installed for you are:

**nosyreaction.py**
  This provides the automatic nosy list maintenance and email sending. The nosy
  reactor (``nosyreaction``) fires when new messages are added to issues.
  The nosy auditor (``updatenosy``) fires when issues are changed and figures
  what changes need to be made to the nosy list (like adding new authors etc)
**statusauditor.py**
  This provides the ``chatty`` auditor which changes the issue status from
  ``unread`` or ``closed`` to ``chatting`` if new messages appear. It also
  provides the ``presetunread`` auditor which pre-sets the status to
  ``unread`` on new items if the status isn't explicitly defined.

See the detectors section in the `design document`__ for details of the
interface for detectors.

__ design.html

Sample additional detectors that have been found useful will appear in the
``detectors`` directory of the Roundup distribution:

**newissuecopy.py**
  This detector sends an email to a team address whenever a new issue is
  created. The address is hard-coded into the detector, so edit it before you
  use it (look for the text 'team@team.host') or you'll get email errors!

XXX give the example here.


Database Content
----------------

Note: if you modify the content of definitional classes, you'll most likely
       need to edit the tracker `detectors`_ to reflect your changes.

Customisation of the special "definitional" classes (eg. status, priority,
resolution, ...) may be done either before or after the tracker is
initialised. The actual method of doing so is completely different in each
case though, so be careful to use the right one.

**Changing content before tracker initialisation**
    Edit the dbinit module in your tracker to alter the items created in using
    the create() methods.


**Changing content after tracker initialisation**
    Use the roundup-admin interface's create, set and retire methods to add,
    alter or remove items from the classes in question.

XXX example


Web Interface
-------------

The web is provided by the roundup.cgi.client module and is used by
roundup.cgi, roundup-server and ZRoundup.
In all cases, we determine which tracker is being accessed
(the first part of the URL path inside the scope of the CGI handler) and pass
control on to the tracker interfaces.Client class - which uses the Client class
from roundup.cgi.client - which handles the rest of
the access through its main() method. This means that you can do pretty much
anything you want as a web interface to your tracker.

Repurcussions of changing the tracker schema
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

If you choose to change the `tracker schema`_ you will need to ensure the web
interface knows about it:

1. Index, item and search pages for the relevant classes may need to have
   properties added or removed,
2. The "page" template may require links to be changed, as might the "home"
   page's content arguments.

How requests are processed
~~~~~~~~~~~~~~~~~~~~~~~~~~

The basic processing of a web request proceeds as follows:

1. figure out who we are, defaulting to the "anonymous" user
2. figure out what the request is for - we call this the "context"
3. handle any requested action (item edit, search, ...)
4. render a template, resulting in HTML output

In some situations, exceptions occur:

- HTTP Redirect  (generally raised by an action)
- SendFile       (generally raised by determine_context)
  here we serve up a FileClass "content" property
- SendStaticFile (generally raised by determine_context)
  here we serve up a file from the tracker "html" directory
- Unauthorised   (generally raised by an action)
  here the action is cancelled, the request is rendered and an error
  message is displayed indicating that permission was not
  granted for the action to take place
- NotFound       (raised wherever it needs to be)
  this exception percolates up to the CGI interface that called the client

Determining web context
~~~~~~~~~~~~~~~~~~~~~~~

To determine the "context" of a request, we look at the URL and the special
request variable ``:template``. The URL path after the tracker identifier
is examined. Typical URL paths look like:

1.  ``/tracker/issue``
2.  ``/tracker/issue1``
3.  ``/tracker/_file/style.css``
4.  ``/cgi-bin/roundup.cgi/tracker/file1``
5.  ``/cgi-bin/roundup.cgi/tracker/file1/kitten.png``

where the "tracker identifier" is "tracker" in the above cases. That means
we're looking at "issue", "issue1", "_file/style.css", "file1" and
"file1/kitten.png" in the cases above. The path is generally only one
entry long - longer paths are handled differently.

a. if there is no path, then we are in the "home" context.
b. if the path starts with "_file" (as in example 3,
   "/tracker/_file/style.css"), then the additional path entry,
   "style.css" specifies the filename of a static file we're to serve up
   from the tracker "html" directory. Raises a SendStaticFile
   exception.
c. if there is something in the path (as in example 1, "issue"), it identifies
   the tracker class we're to display.
d. if the path is an item designator (as in examples 2 and 4, "issue1" and
   "file1"), then we're to display a specific item.
e. if the path starts with an item designator and is longer than
   one entry (as in example 5, "file1/kitten.png"), then we're assumed
   to be handling an item of a
   FileClass, and the extra path information gives the filename
   that the client is going to label the download with (ie
   "file1/kitten.png" is nicer to download than "file1"). This
   raises a SendFile exception.

Both b. and e. stop before we bother to
determine the template we're going to use. That's because they
don't actually use templates.

The template used is specified by the ``:template`` CGI variable,
which defaults to:

- only classname suplied:          "index"
- full item designator supplied:   "item"


Performing actions in web requests
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

When a user requests a web page, they may optionally also request for an
action to take place. As described in `how requests are processed`_, the
action is performed before the requested page is generated. Actions are
triggered by using a ``:action`` CGI variable, where the value is one of:

login
 Attempt to log a user in.
logout
 Log the user out - make them "anonymous".
register
 Attempt to create a new user based on the contents of the form and then log
 them in.
edit
 Perform an edit of an item in the database. There are some special form
 elements you may use:

 :link=designator:property and :multilink=designator:property
  The value specifies an item designator and the property on that
  item to add _this_ item to as a link or multilink.
 :note
  Create a message and attach it to the current item's
  "messages" property.
 :file
  Create a file and attach it to the current item's
  "files" property. Attach the file to the message created from
  the :note if it's supplied.
 :required=property,property,...
  The named properties are required to be filled in the form.

new
 Add a new item to the database. You may use the same special form elements
 as in the "edit" action.

editCSV
 Performs an edit of all of a class' items in one go. See also the
 *class*.csv templating method which generates the CSV data to be edited, and
 the "_generic.index" template which uses both of these features.

search
 Mangle some of the form variables.

 Set the form ":filter" variable based on the values of the
 filter variables - if they're set to anything other than
 "dontcare" then add them to :filter.

 Also handle the ":queryname" variable and save off the query to
 the user's query list.

Each of the actions is implemented by a corresponding *actionAction* (where
"action" is the name of the action) method on
the roundup.cgi.Client class, which also happens to be in your tracker as
interfaces.Client. So if you need to define new actions, you may add them
there (see `definining new web actions`_).

Each action also has a corresponding *actionPermission* (where
"action" is the name of the action) method which determines
whether the action is permissible given the current user. The base permission
checks are:

login
 Determine whether the user has permission to log in.
 Base behaviour is to check the user has "Web Access".
logout
 No permission checks are made.
register
 Determine whether the user has permission to register
 Base behaviour is to check the user has "Web Registration".
edit
 Determine whether the user has permission to edit this item.
 Base behaviour is to check the user can edit this class. If we're
 editing the "user" class, users are allowed to edit their own
 details. Unless it's the "roles" property, which requires the
 special Permission "Web Roles".
new
 Determine whether the user has permission to create (edit) this item.
 Base behaviour is to check the user can edit this class. No
 additional property checks are made. Additionally, new user items
 may be created if the user has the "Web Registration" Permission.
editCSV
 Determine whether the user has permission to edit this class.
 Base behaviour is to check the user can edit this class.
search
 Determine whether the user has permission to search this class.
 Base behaviour is to check the user can view this class.


Default templates
~~~~~~~~~~~~~~~~~

Most customisation of the web view can be done by modifying the templates in
the tracker **html** directory. There are several types of files in there:

page
  defines the overall look of your tracker. When you
  view an issue, it appears inside this template. When you view an index, it
  also appears inside this template.
home
  the default page displayed when no other page is indicated by the user
home.classlist
  a special version of the default page that lists the classes in the tracker
*classname*.item
  displays an item of the *classname* class
*classname*.index
  displays a list of *classname* items
*classname*.search
  displays a search page for *classname* items
_generic.index
  used to display a list of items where there is no *classname*.index available
_generic.help
  used to display a "class help" page where there is no *classname*.help
user.register
  a special page just for the user class that renders the registration page
style.css
  a static file that is served up as-is

Overall Look - "page" template
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

XXX

How the templates work
~~~~~~~~~~~~~~~~~~~~~~

Roundup's templates consist of special attributes on your template tags. These
attributes form the Template Attribute Language, or TAL. The commands are:


tal:define="variable expression; variable expression; ..."
   Define a new variable that is local to this tag and its contents. For
   example::

      <html tal:define="title request/description">
       <head><title tal:content="title"></title></head>
      </html>

   In the example, the variable "title" is defined as being the result of the
   expression "request/description". The tal:content command inside the <html>
   tag may then use the "title" variable.

tal:condition="expression"
   Only keep this tag and its contents if the expression is true. For example::

     <p tal:condition="python:request.user.hasPermission('View', 'issue')">
      Display some issue information.
     </p>

   In the example, the <p> tag and its contents are only displayed if the
   user has the View permission for issues. We consider the number zero, a
   blank string, an empty list, and the built-in variable nothing to be false
   values. Nearly every other value is true, including non-zero numbers, and
   strings with anything in them (even spaces!).

tal:repeat="variable expression"
   Repeat this tag and its contents for each element of the sequence that the
   expression returns, defining a new local variable and a special "repeat"
   variable for each element. For example::

     <tr tal:repeat="u user/list">
      <td tal:content="u/id"></td>
      <td tal:content="u/username"></td>
      <td tal:content="u/realname"></td>
     </tr>

   The example would iterate over the sequence of users returned by
   "user/list" and define the local variable "u" for each entry.

tal:replace="expression"
   Replace this tag with the result of the expression. For example::

    <span tal:replace="request/user/realname"></span>

   The example would replace the <span> tag and its contents with the user's
   realname. If the user's realname was "Bruce" then the resultant output
   would be "Bruce".

tal:content="expression"
   Replace the contents of this tag with the result of the expression. For
   example::

    <span tal:content="request/user/realname">user's name appears here</span>

   The example would replace the contents of the <span> tag with the user's
   realname. If the user's realname was "Bruce" then the resultant output
   would be "<span>Bruce</span>".

tal:attributes="attribute expression; attribute expression; ..."
   Set attributes on this tag to the results of expressions. For example::

     <a tal:attributes="href string:user${request/user/id}">My Details</a>

   In the example, the "href" attribute of the <a> tag is set to the value of
   the "string:user${request/user/id}" expression, which will be something
   like "user123".

tal:omit-tag="expression"
   Remove this tag (but not its contents) if the expression is true. For
   example::

      <span tal:omit-tag="python:1">Hello, world!</span>

   would result in output of::

      Hello, world!

Note that the commands on a given tag are evaulated in the order above, so
*define* comes before *condition*, and so on.

Additionally, a tag is defined, tal:block, which is removed from output. Its
content is not, but the tag itself is (so don't go using any tal:attributes
commands on it). This is useful for making arbitrary blocks of HTML
conditional or repeatable (very handy for repeating multiple table rows,
which would othewise require an illegal tag placement to effect the repeat).

The expressions you may use in the attibute values may be one of the following
three forms:

Path Expressions - eg. ``item/status/checklist``
   These are object attribute / item accesses. Roughly speaking, the path
   ``item/status/checklist`` is broken into parts ``item``, ``status``
   and ``checklist``. The ``item`` part is the root of the expression.
   We then look for a ``status`` attribute on ``item``, or failing that, a
   ``status`` item (as in ``item['status']``). If that
   fails, the path expression fails. When we get to the end, the object we're
   left with is evaluated to get a string - methods are called, objects are
   stringified. Path expressions may have an optional ``path:`` prefix, though
   they are the default expression type, so it's not necessary.

   XXX | components of expressions

   XXX "nothing" and "default"

String Expressions - eg. ``string:hello ${user/name}``
   These expressions are simple string interpolations (though they can be just
   plain strings with no interpolation if you want. The expression in the
   ``${ ... }`` is just a path expression as above.

Python Expressions - eg. ``python: 1+1``
   These expressions give the full power of Python. All the "root level"
   variables are available, so ``python:item.status.checklist()`` would be
   equivalent to ``item/status/checklist``, assuming that ``checklist`` is
   a method.

Information available to templates
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The following variables are available to templates.

.. taken from roundup.cgi.templating.RoundupPageTemplate docstring

*context*
  The current context. This is either None, a wrapper around a
  hyperdb class (an HTMLClass) or a wrapper around a hyperdb item (an
  HTMLItem).
*request*
  Includes information about the current request, including:
   - the url
   - the current index information (``filterspec``, ``filter`` args,
     ``properties``, etc) parsed out of the form. 
   - methods for easy filterspec link generation
   - *user*, the current user item as an HTMLItem instance
   - *form*
     The current CGI form information as a mapping of form argument
     name to value
*tracker*
  The current tracker
*db*
  The current database, through which db.config may be reached.
*nothing*
  XXX a special variable
*default*
  XXX a special variable

The context variable
::::::::::::::::::::

The *context* variable is one of three things based on the current context
(see `determining web context`_ for how we figure this out):

1. if we're looking at a "home" page, then it's None
2. if we're looking at a specific hyperdb class, it's an HTMLClass instance
3. if we're looking at a specific hyperdb item, it's an HTMLItem instance

If the context is not None, we can access the properties of the class or item.
The only real difference between cases 2 and 3 above are:

1. the properties may have a real value behind them, and this will appear if
   the property is displayed through ``context/property`` or
   ``context/property/field``.
2. the context's "id" property will be a false value in the second case, but
   a real, or true value in the third. Thus we can determine whether we're
   looking at a real item from the hyperdb by testing "context/id".


The request variable
::::::::::::::::::::

The request variable is packed with information about the current request.

.. taken from roundup.cgi.templating.HTMLRequest docstring

=========== ================================================================
Variable    Holds
=========== ================================================================
form        the CGI form as a cgi.FieldStorage
env         the CGI environment variables
url         the current URL path for this request
base        the base URL for this tracker
user        a HTMLUser instance for this user
classname   the current classname (possibly None)
template    the current template (suffix, also possibly None)
form        the current CGI form variables in a FieldStorage
=========== ================================================================

**Index page specific variables (indexing arguments)**

=========== ================================================================
Variable    Holds
=========== ================================================================
columns     dictionary of the columns to display in an index page
show        a convenience access to columns - request/show/colname will
              be true if the columns should be displayed, false otherwise
sort        index sort column (direction, column name)
group       index grouping property (direction, column name)
filter      properties to filter the index on
filterspec  values to filter the index on
search_text text to perform a full-text search on for an index
=========== ================================================================


Displaying Properties
~~~~~~~~~~~~~~~~~~~~~

Properties appear in the user interface in three contexts: in indices, in
editors, and as search arguments.
For each type of property, there are several display possibilities.
For example, in an index view, a string property may just be
printed as a plain string, but in an editor view, that property may be
displayed in an editable field.


Index Views
~~~~~~~~~~~

This is one of the class context views. It is also the default view for
classes. The template used is "*classname*.index".

Index View Specifiers
:::::::::::::::::::::

An index view specifier (URL fragment) looks like this (whitespace has been
added for clarity)::

     /issue?status=unread,in-progress,resolved&
            topic=security,ui&
            :group=+priority&
            :sort=-activity&
            :filters=status,topic&
            :columns=title,status,fixer

The index view is determined by two parts of the specifier: the layout part and
the filter part. The layout part consists of the query parameters that begin
with colons, and it determines the way that the properties of selected items
are displayed. The filter part consists of all the other query parameters, and
it determines the criteria by which items are selected for display.
The filter part is interactively manipulated with the form widgets displayed in
the filter section. The layout part is interactively manipulated by clicking on
the column headings in the table.

The filter part selects the union of the sets of items with values matching any
specified Link properties and the intersection of the sets of items with values
matching any specified Multilink properties.

The example specifies an index of "issue" items. Only items with a "status" of
either "unread" or "in-progres" or "resolved" are displayed, and only items
with "topic" values including both "security" and "ui" are displayed. The items
are grouped by priority, arranged in ascending order; and within groups, sorted
by activity, arranged in descending order. The filter section shows filters for
the "status" and "topic" properties, and the table includes columns for the
"title", "status", and "fixer" properties.

Filtering of indexes
::::::::::::::::::::

TODO

Searching Views
~~~~~~~~~~~~~~~

This is one of the class context views. The template used is typically
"*classname*.search".

TODO

Item Views
~~~~~~~~~~

The basic view of a hyperdb item is provided by the "*classname*.item"
template. It generally has three sections; an "editor", a "spool" and a
"history" section.



Editor Section
::::::::::::::

The editor section is used to manipulate the item - it may be a
static display if the user doesn't have permission to edit the item.

Here's an example of a basic editor template (this is the default "classic"
template issue item edit form - from the "issue.item" template)::

 <table class="form">
 <tr>
  <th nowrap>Title</th>
  <td colspan=3 tal:content="structure python:context.title.field(size=60)">title</td>
 </tr>
 
 <tr>
  <th nowrap>Priority</th>
  <td tal:content="structure context/priority/menu">priority</td>
  <th nowrap>Status</th>
  <td tal:content="structure context/status/menu">status</td>
 </tr>
 
 <tr>
  <th nowrap>Superseder</th>
  <td>
   <span tal:replace="structure python:context.superseder.field(showid=1, size=20)" />
   <span tal:replace="structure python:db.issue.classhelp('id,title', label='list', width=500)" />
   <span tal:condition="context/superseder">
    <br>View: <span tal:replace="structure python:context.superseder.link(showid=1)" />
   </span>
  </td>
  <th nowrap>Nosy List</th>
  <td>
   <span tal:replace="structure context/nosy/field" />
   <span tal:replace="structure python:db.user.classhelp('username,realname,address,phone', label='list', width=500)" />
  </td>
 </tr>
 
 <tr>
  <th nowrap>Assigned To</th>
  <td tal:content="structure context/assignedto/menu">
   assignedto menu
  </td>
  <td>&nbsp;</td>
  <td>&nbsp;</td>
 </tr>
 
 <tr>
  <th nowrap>Change Note</th>
  <td colspan=3>
   <textarea name=":note" wrap="hard" rows="5" cols="60"></textarea>
  </td>
 </tr>
 
 <tr>
  <th nowrap>File</th>
  <td colspan=3><input type="file" name=":file" size="40"></td>
 </tr>
 
 <tr>
  <td>&nbsp;</td>
  <td colspan=3 tal:content="structure context/submit">
   submit button will go here
  </td>
 </tr>
 </table>


When a change is submitted, the system automatically generates a message
describing the changed properties. As shown in the example, the editor
template can use the ":note" and ":file" fields, which are added to the
standard change note message generated by Roundup.

Spool Section
:::::::::::::

The spool section lists related information like the messages and files of
an issue.

TODO


History Section
:::::::::::::::

The final section displayed is the history of the item - its database journal.
This is generally generated with the template::

 <tal:block tal:replace="structure context/history" />

*To be done:*

*The actual history entries of the item may be accessed for manual templating
through the "journal" method of the item*::

 <tal:block tal:repeat="entry context/journal">
  a journal entry
 </tal:block>

*where each journal entry is an HTMLJournalEntry.*


Access Controls
---------------

A set of Permissions are built in to the security module by default:

- Edit (everything)
- View (everything)

The default interfaces define:

- Web Registration
- Web Access
- Web Roles
- Email Registration
- Email Access

These are hooked into the default Roles:

- Admin (Edit everything, View everything, Web Roles)
- User (Web Access, Email Access)
- Anonymous (Web Registration, Email Registration)

And finally, the "admin" user gets the "Admin" Role, and the "anonymous" user
gets the "Anonymous" assigned when the database is initialised on installation.
The two default schemas then define:

- Edit issue, View issue (both)
- Edit file, View file (both)
- Edit msg, View msg (both)
- Edit support, View support (extended only)

and assign those Permissions to the "User" Role. New users are assigned the
Roles defined in the config file as:

- NEW_WEB_USER_ROLES
- NEW_EMAIL_USER_ROLES

You may alter the configuration variables to change the Role that new web or
email users get, for example to not give them access to the web interface if
they register through email.

You may use the ``roundup-admin`` "``security``" command to display the
current Role and Permission configuration in your tracker.

Adding a new Permission
~~~~~~~~~~~~~~~~~~~~~~~

When adding a new Permission, you will need to:

1. add it to your tracker's dbinit so it is created
2. enable it for the Roles that should have it (verify with
   "``roundup-admin security``")
3. add it to the relevant HTML interface templates
4. add it to the appropriate xxxPermission methods on in your tracker
   interfaces module



-----------------

Back to `Table of Contents`_

.. _`Table of Contents`: index.html