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Smarty Tips And Tricks
Chapter 18. Tips & Tricks
Blank Variable Handling
There may be times when you want to print a default value
for an empty variable instead of printing nothing, such as printing " "
so that table backgrounds work properly. Many would use an {if} statement to
handle this, but there is a shorthand way with Smarty, using the
default variable
modifier.
Example 18-1. Printing when a variable is empty
{* the long way *}
{if $title eq ""}
{else}
{$title}
{/if}
{* the short way *}
{$title|default:" "}
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Default Variable Handling
If a variable is used frequently throughout your templates,
applying the default modifier every time it is mentioned can get a bit ugly. You
can remedy this by assigning the variable its default value with the assign
function.
Example 18-2. Assigning a template variable its default value
{* do this somewhere at the top of your template *}
{assign var="title" value=$title|default:"no title"}
{* if $title was empty, it now contains the value "no title" when you print it *}
{$title}
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Passing variable title to header template
When the majority of your templates use the same headers and footers, it is
common to split those out into their own templates and include them. But what if
the header needs to have a different title, depending on what page you are
coming from? You can pass the title to the header when it is included.
Example 18-3. Passing the title variable to the header template
mainpage.tpl
------------
{include file="header.tpl" title="Main Page"}
{* template body goes here *}
{include file="footer.tpl"}
archives.tpl
------------
{config_load file="archive_page.conf"}
{include file="header.tpl" title=#archivePageTitle#}
{* template body goes here *}
{include file="footer.tpl"}
header.tpl
----------
<HTML>
<HEAD>
<TITLE>{$title|default:"BC News"}</TITLE>
</HEAD>
<BODY>
footer.tpl
----------
</BODY>
</HTML>
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When the main page is drawn, the title of "Main Page" is
passed to the header.tpl, and will subsequently be used as the title. When the
archives page is drawn, the title will be "Archives". Notice in the archive
example, we are using a variable from the archives_page.conf file instead of a
hard coded variable. Also notice that "BC News" is printed if the $title
variable is not set, using the
default variable modifier.
Dates
As a rule of thumb, always pass dates to Smarty as timestamps. This allows
template designers to use date_format for full control over date formatting, and
also makes it easy to compare dates if necessary.
Note: As of Smarty 1.4.0, you can pass dates to Smarty as unix
timestamps, mysql timestamps, or any date parsable by strtotime().
Example 18-4. using date_format
This will output:
{$startDate|date_format:"%Y/%m/%d"}
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This will output:
{if $date1 < $date2}
...
{/if}
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When using {html_select_date} in a template, The programmer will most likely
want to convert the output from the form back into timestamp format. Here is a
function to help you with that.
Example 18-5. converting form date elements back to a timestamp
<?php
// this
assumes your form elements are named
// startDate_Day, startDate_Month, startDate_Year
$startDate
=
makeTimeStamp($startDate_Year,
$startDate_Month,
$startDate_Day);
function
makeTimeStamp($year="",
$month="",
$day="")
{
if(empty($year))
{
$year
=
strftime("%Y");
}
if(empty($month))
{
$month
=
strftime("%m");
}
if(empty($day))
{
$day
=
strftime("%d");
}
return mktime(0,
0,
0,
$month,
$day,
$year);
}
?>
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WAP/WML
WAP/WML templates require a php Content-Type header to be
passed along with the template. The easist way to do this would be to write a
custom function that prints the header. If you are using caching, that won't
work so we'll do it using the insert tag (remember insert tags are not cached!)
Be sure that there is nothing output to the browser before the template, or else
the header may fail.
Example 18-6. using insert to write a WML Content-Type header
<?php
//
be sure apache is configure for the .wml
extensions!
// put this function somewhere in your application, or in
Smarty.addons.php
function
insert_header($params)
{
// this
function expects $content argument
if (empty($params['content']))
{
return;
}
header($params['content']);
return;
}
?>
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your Smarty template
must begin with the insert tag :
{insert name=header content="Content-Type: text/vnd.wap.wml"}
<?xml version="1.0"?>
<!DOCTYPE wml PUBLIC "-//WAPFORUM//DTD WML 1.1//EN" "http://www.wapforum.org/DTD/wml_1.1.xml">
<!-- begin new wml deck -->
<wml>
<!-- begin first card -->
<card>
<do type="accept">
<go class="blue" HREF="p_#two"/>
</do>
<p>
Welcome to WAP with Smarty!
Press OK to continue...
</p>
</card>
<!-- begin second card -->
<card id="two">
<p>
Pretty easy isn't it?
</p>
</card>
</wml>
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Componentized Templates
Traditionally, programming templates into your applications
goes as follows: First, you accumulate your variables within your PHP
application, (maybe with database queries.) Then, you instantiate your Smarty
object, assign the variables and display the template. So lets say for example
we have a stock ticker on our template. We would collect the stock data in our
application, then assign these variables in the template and display it. Now
wouldn't it be nice if you could add this stock ticker to any application by
merely including the template, and not worry about fetching the data up front?
You can do this by writing a custom plugin for fetching the content and
assigning it to a template variable.
Example 18-7. componentized template
<?php
// drop file "function.load_ticker.php"
in plugin directory
// setup our function for fetching stock data
function
fetch_ticker($symbol)
{
// put
logic here that fetches $ticker_info
// from some ticker resource
return
$ticker_info;
}
function
smarty_function_load_ticker($params,
&$smarty)
{
// call the
function
$ticker_info
=
fetch_ticker($params['symbol']);
// assign
template variable
$smarty->assign($params['assign'],
$ticker_info);
}
?>
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{* in index.tpl *}
{load_ticker symbol="YHOO" assign="ticker"}
Stock Name: {$ticker.name} Stock Price: {$ticker.price}
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Obfuscating E-mail Addresses
Do you ever wonder how your E-mail address gets on so many
spam mailing lists? One way spammers collect E-mail addresses is from web pages.
To help combat this problem, you can make your E-mail address show up in
scrambled javascript in the HTML source, yet it it will look and work correctly
in the browser. This is done with the mailto plugin.
Example 18-8. Example of Obfuscating an E-mail Address
{* in index.tpl *}
Send inquiries to
{mailto address=$EmailAddress encode="javascript" subject="Hello"}
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Technical Note: This method isn't 100% foolproof. A spammer
could conceivably program his e-mail collector to decode these values,
but not likely.
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