NAME¶
HTML::Template::Plugin::Dot - Add Magic Dot notation to HTML::Template
SYNOPSIS¶
use HTML::Template::Pluggable;
use HTML::Template::Plugin::Dot;
my $t = HTML::Template::Pluggable->new(...);
Now you can use chained accessor calls and nested hashrefs as params, and access
them with a dot notation. You can even pass arguments to the methods.
For example, in your code:
$t->param( my_complex_struct => $struct );
And then in your template you can reference specific values in the structure:
my_complex_struct.key.obj.accessor('hash')
my_complex_struct.other_key
DESCRIPTION¶
By adding support for this dot notation to HTML::Template, the programmers' job
of sending data to the template is easier, and designers have easier access to
more data to display in the template, without learning any more tag syntax.
EXAMPLES¶
Class::DBI integration¶
Class::DBI accessors can be used in the template. If the accessor is never
called in the template, that data doesn't have to be loaded.
In the code:
$t->param ( my_row => $class_dbi_obj );
In the template:
my_row.last_name
This extends to related objects or inflated columns (commonly used for date
fields). Here's an example with a date column that's inflated into a DateTime
object:
my_row.my_date.mdy('/')
my_row.my_date.strftime('%D')
Of course, if date formatting strings look scary to the designer, you can keep
them in the application, or even a database layer to insure consistency in all
presentations.
Here's an example with related objects. Suppose you have a Customer object, that
has_a BillingAddress object attached to it. Then you could say something like
this:
<tmpl_if customer.billing_address>
<tmpl_var customer.billing_address.street>
<tmpl_var customer.billing_address.city>
...
</tmpl_if>
More complex uses¶
The dot notation allows you to pass arguments to method calls (as in the
"my_date.dmy('/')" example above). In fact, you can pass other
objects in the template as well, and this enables more complex usage. Imagine
we had a (fictional) Formatter object which could perform some basic string
formatting functions. This could be used in e.g. currencies, or dates.
In your code:
$t->param( Formatter => Formatter->new,
order => $order_obj );
In your template:
Amount: <tmpl_var Formatter.format_currency('US',order.total_amount)>
(hint: see Number::Format)
This even extends to references to plain tmpl_vars in your template:
$t->param( Formatter => Formatter->new,
plain => 'Jane' );
<tmpl_var Formatter.reverse(plain)> is
<tmpl_var plain> backwards
TMPL_LOOPs¶
As of version 0.94, the dot notation is also supported on TMPL_LOOP tags (but
see the "LIMITATIONS" section).
Given an object method (or a hash key) that returns an array or a reference to
an array, we will unwrap that array for use in the loop. Individual array
elements are mapped to a hash "{ 'this' => $elt }", so that you
can refer to them in TMPL_VARs as "this.something".
An example might help. Let's use the canonical Class::DBI example for our data.
Suppose you have an $artist object, which has_many CDs. You can now pass just
the $artist object, and handle the loops in the template:
$t->param( artist => $artist );
The template:
<tmpl_var artist.name> has released these albums:
<tmpl_loop artist.cds>
<tmpl_var this.title> - <tmpl_var this.year>
</tmpl_loop>
As you can see, each element from the artist.
cds() array is called
"this" by default. You can supply your own name by appending ':
name' like this:
<tmpl_loop artist.cds:cd>
<tmpl_var cd.title>
...
That's not the end of it! You can even nest these loops, displaying the Tracks
for each CD like so:
<tmpl_loop artist.cds:cd>
<tmpl_var cd.title>
<tmpl_loop cd.tracks:track>
- <tmpl_var track.title> ( <tmpl_var track.tracktime> )
</tmpl_loop>
</tmpl_loop>
LIMITATIONS¶
- •
- Casing of parameter names
Casing of parameter names follows the option "case_sensitive" of
HTML::Template. If you do not use that option, all parameter names are
converted to lower case. I suggest turning this option on to avoid
confusion.
- •
- Quotes and spaces
Because of the way HTML::Template parses parameter names (which follows the
rules of HTML attributes), you have to be careful when your expressions
contain spaces or quote characters. You can say "<tmpl_var
something.without.spaces>", but not "<tmpl_var something
with spaces>". You can use single or double quotes around your
entire expression, and then use the other one inside: "<tmpl_var
name="some.method('with arguments')">" This is the
recommended way to write your expressions.
(Note: within expressions, the characters in "[`'"]" are
recognised as quote characters. So if you need to pass literal quotes to a
method, you could do it like this: "<tmpl_var
name='some.method(`need a " here`)'>". )
No attempt to even measure performance has been made. For now the focus is on
usability and stability. If you carry out benchmarks, or have suggestions for
performance improvements, be sure to let us know!
CONTRIBUTING¶
Patches, questions and feedback are welcome. This project is managed using the
darcs source control system (
http://www.darcs.net/ ). A public darcs archive
is here:
http://cgiapp.erlbaum.net/darcs_hive/ht-pluggable/
AUTHORS¶
Mark Stosberg, <mark@summersault.com>; Rhesa Rozendaal,
<rhesa@cpan.org>
Copyright & License¶
Parts copyright 2006 Mark Stosberg
Parts copyright 2006 Rhesa Rozendaal
This program is free software; you can redistribute it and/or modify it under
the same terms as perl itself.