Zope Concepts - DTML

Zope Concepts - DTML

Valentin Baciu

Finsiel Romania

Tirana, 7 June 2005

Zope Scripting languages - DTML

• DTML (Document Template Markup Language) • is a facility for generating textual information using a template document and

application information stored in Zope. • It is used in Zope primarily to generate Hypertext Markup Language (HTML) files• Can be used to generate SQL commands in Zope SQL Methods.

• DTML dynamically generates, controls and formats content.• DTML is server side scripting language, executed by the Zope server

DTML

• DTML is a tag based presentation and scripting language• That means that tags embedded in your HTML cause parts of your page to be

replaced with “computed” content• The code placed in DTML Objects is constrained by Zope’s security policy• DTML can be added in

– DTML Documents – supports properties– DTML Methods – used to carry out actions

• DTML makes the reuse of content and layout possible

DTML tags

• The format for DTML tags is the following

<dtml-tag name attribute1="value1" attribute2="value2" ... >

• The name attribute is used to obtain data by name. The data is looked up using a set of rules• When the value of a name attribute is looked up, the value is automatically called, if possible.

If the value is a Zope Document or Python document template, it is rendered before being given to the tag that uses the name attribute.

<dtml-var standard_html_header>

standard_html_header is a Zope document which provides standard HTML to be included at the top of every page. When the var tag above is used, the DTML in standard_html_header is rendered and the result is inserted in the current document.

• The expr attribute allows complex expressions to be evaluated.

DTML tags

• dtml-var - The dtml-var tag is used to perform simple variable substitutions.• dtml-if/dtml-unless - supports the conditional insertion of text based on DTML

variables or expressions.• dtml-in - is used to iterate over a sequence of objects, iterative insertion,• dtml-with - can be used to expand the namespace of a document template by

adding attributes (or mapping keys) from an object which already exists in the document template namespace.

• dtml-let - multiple assignments with this tag• dtml-call - evaluating names or expressions without generating text• dtml-raise – used for raising errors

DTML tags - continued

• dtml-try (dtml-except/dtml-finnaly) - catch and handle these problematic exceptions within a block of DTML code, This allows you to anticipate and handle errors yourself,

• dtml-comment - provides a way to exclude source text from the rendered text.• dtml-return - used to return data rather than text from a DTML method.• dtml-tree - displaying information hierarchically• dtml-sendmail - used to send an electronic message using the Simple Mail

Transport Protocol (SMTP). No text in the output• dtml-mime - used in conjunction with the dtml-sendmail tag to send

attachments along with electronic mail messages.

Examples of dtml-var usage

• <dtml-var x> includes the value of x. x is looked up in the current DTML namespace,

called, if it is callable, and the result converted to a string. • <dtml-var expr="x+y">

includes the value of x+y. • <dtml-var x html_quote missing>

includes the value of x with the special HTML characters < and & quoted. If x is not bound in the current DTML namespace, no KeyError is raise but the (default) value of missing, the empty string, is included.

• <dtml-var x url> includes the URL of x.

Edit the front page of your site

• Suppose we have two folders ‘cars’ and ‘trucks’ in our Zope server

• Homepage for the site which gives access to the above information (index_html) looks like this:


<p>This site presents information about various types of cars.</p>

<ul>

<li><a href="/cars">Cars</a>

<li><a href="/trucks">Trucks</a>

</ul>

<dtml-var standard_html_footer>

How the page is constructedTo provide consistent look over the site the following methods are used:

• standard_html_header - The standard Zope header object. By convention this object displays an HTML header <html><head><title><dtml-var title_or_id></title></head><body bgcolor="#FFFFFF">

<h2><dtml-var site_title></h2>

<dtml-var logo>

• index_html - The name of the default Zope object in a Folder. When you view a Folder the index_html object will be displayed unless you specify otherwise. <dtml-var standard_html_header>

<h2><dtml-var title_or_id></h2>

<p>This is the section about <dtml-var title_or_id>.</p>


• standard_html_footer - The standard Zope footer object. By convention this object displays an HTML footer<p><hr>

<a href="mailto:<dtml-var webmaster>">Feedback to Webmaster</a><br>

Page last modified: <dtml-var bobobase_modification_time>

</p>

</body></html>

Customising views

• Customise default views for the folders• in the ‘cars’ folder, we should add a DTML Method• Give it the Id 'index_html'• Edit this method and replace the text with the following:


<h2><dtml-var title_or_id></h2>

<p>This is the section about <dtml-var title_or_id>.</p>

<ul>

<dtml-in objectValues>

<li><a href="<dtml-var absolute_url>"><dtml-var title_or_id></a>

</dtml-in>

</ul>


Creating a breadcrumb trail

• In the Root folder, a DTML Method called 'breadcrumbtrail‘ should be added• It should contain the following text and called form the standard_html_header:<p>

<dtml-call "REQUEST.set('stopshort', 0)">

<dtml-if expr="_['id'] == 'index_html' or PARENTS[0].id == _['id'] or absolute_url(1) == ''">

<dtml-call "REQUEST.set('stopshort',1)">

</dtml-if>

<dtml-in PARENTS skip_unauthorized reverse>

<dtml-if "stopshort and _['sequence-end']">

<dtml-var title_or_id size=25>

<dtml-else>

<a href="<dtml-var absolute_url>"><dtml-var title_or_id size=25></a> >>

</dtml-if>

</dtml-in>

<dtml-unless stopshort>

<dtml-var title_or_id size=25>

</dtml-unless>

</p>

Zope concepts

Your Website structure

a simple hierarchical folder structure

How acquisition works

from …/cars/diesel only the attributes of:

- cars folder

- Root folder

are visible