1Template::FAQ(3) User Contributed Perl Documentation Template::FAQ(3)
2
6 Template::FAQ - Frequently Asked Questions about the Template Toolkit
7
9 Why doesn't [% a = b IF c %] work as expected?
10 There's a limitation in the TT2 parser which means that the following
11 code doesn't work as you might expect:
12 [% a = b IF c %]
14 The parser interprets it as an attempt to set "a" to the result of "b
16 IF c", like this:
17 [% a = (b IF c) %]
19 If you want to set "a = b" only if "c" is true, then do this instead:
21 [% SET a = b IF c %]
23 The explicit "SET" keyword gives the parser the clue it needs to do the
25 right thing.
26 NOTE: this will be fixed in TT3
28 If I'm using TT to write out a TT template, is there a good way to escape
30 [% and %]?
31 You can do something like this:
32 [% stag = "[\%"
34 etag = "%\]"
35 %]
36 and then:
38 [% stag; 'hello'; etag %]
40 Or you can use the "TAGS" directive, like so:
42 [% TAGS [- -] %]
44 [- INCLUDE foo -] # is a directive
45 [% INCLUDE foo %] # not a directive
46 How do I iterate over a hash?
48 This is covered in the Template::Manual::VMethods section of the
49 manual. A list of all the keys that are in the hash can be obtained
50 with the "keys" virtual method. You can then iterate over that list and
51 by looking up each key in turn get the value.
52 [% FOREACH key = product.keys %]
54 [% key %] => [% product.$key %]
55 [% END %]
56
58 How do I get the Table plugin to order data across rather than down?
59 Order the data into rows:
60 Steve Karen Jeff
62 Brooklyn Nantucket Fairfax
63 NY MA VA
64 [% USE table(data, rows=3) %]
66 Then ask for each column
68 [% FOREACH column = table.cols %]
70 And then print each item in the column going across the output rows
72 [% FOREACH item = column %]
74 <td>[% item %]</td>
75 [% END %]
76 Accessing Cookies
78 Jeff Boes <jboes@nexcerpt.com> asks:
79 Does anyone have a quick-n-dirty approach to accessing
81 cookies from templates?
82 Jonas Liljegren answers:
84 [% USE CGI %]
86 <p>The value is [% CGI.cookie('cookie_name') | html %]
88 You will need to have Template::Plugin::CGI installed.
90
92 Can I serve templates from a database?
93 Short answer: yes, Chris Nandor has done this for Slash. You need to
94 subclass Template::Provider. See the mailing list archives for further
95 info.
96 Can I fetch templates via http?
98 To do the job properly, you should subclass Template::Provider to
99 "Template::Provider::HTTP" and use a "PREFIX_MAP" option to bind the
100 "http" template prefix to that particular provider (you may want to go
101 digging around in the Changes file around version 2.01 for more info on
102 "PREFIX_MAP" - it may not be properly documented anywhere else...yet!).
103 e.g.
104 use Template::Provider::HTTP;
106 my $file = Template::Provider( INCLUDE_PATH => [...] );
108 my $http = Template::Provider::HTTP->new(...);
109 my $tt2 = Template->new({
110 LOAD_TEMPLATES => [ $file, $http ],
111 PREFIX_MAP => {
112 file => '0', # file:foo.html
113 http => '1', # http:foo.html
114 default => '0', # foo.html => file:foo.html
115 }
116 });
117 Now a template specified as:
119 [% INCLUDE foo %]
121 will be served by the 'file' provider (the default). Otherwise you can
123 explicitly add a prefix:
124 [% INCLUDE file:foo.html %]
126 [% INCLUDE http:foo.html %]
127 [% INCLUDE http://www.xyz.com/tt2/header.tt2 %]
128 This same principal can be used to create a DBI template provider.
130 e.g.
131 [% INCLUDE dbi:foo.html %]
133 Alas, we don't yet have a DBI provider as part of the Template Toolkit.
135 There has been some talk on the mailing list about efforts to develop
136 DBI and/or HTTP providers but as yet no-one has stepped forward to take
137 up the challenge...
138 In the mean time, Craig Barrat's post from the mailing list has some
140 useful pointers on how to achieve this using existing modules. See
141 <http://tt2.org/pipermail/templates/2001-May/000954.html>
142
144 How can I find out the name of the main template being processed?
145 The "template" variable contains a reference to the Template::Document
146 object for the main template you're processing (i.e. the one provided
147 as the first argument to the Template process() method). The "name"
148 method returns its name.
149 [% template.name %] # e.g. index.html
151 How can I find out the name of the current template being processed?
153 The "template" variable always references the main template being
154 processed. So even if you call [% INCLUDE header %], and that calls [%
155 INCLUDE menu %], the "template" variable will be unchanged.
156 index.html:
158 [% template.name %] # index.html
160 [% INCLUDE header %]
161 header:
163 [% template.name %] # index.html
165 [% INCLUDE menu %]
166 menu:
168 [% template.name %] # index.html
170 In contrast, the "component" variable always references the current
172 template being processed.
173 index.html
175 [% component.name %] # index.html
177 [% INCLUDE header %]
178 header:
180 [% component.name %] # header
182 [% INCLUDE menu %]
183 menu:
185 [% component.name %] # menu
187 How do I print the modification time of the template or component?
189 The "template" and "component" variables reference the main template
190 and the current template being processed (see previous questions). The
191 "modtime" method returns the modification time of the corresponding
192 template file as a number of seconds since the Unix epoch (00:00:00 GMT
193 1st January 1970).
194 This number doesn't mean much to anyone (except perhaps serious Unix
196 geeks) so you'll probably want to use the Date plugin to format it for
197 human consumption.
198 [% USE Date %]
200 [% template.name %] last modified [% Date.format(template.modtime) %]
201 How can I configure variables on a per-request basis?
203 One easy way to achieve this is to define a single "PRE_PROCESS"
204 template which loads in other configuration files based on variables
205 defined or other conditions.
206 For example, my setup usually looks something like this:
208 PRE_PROCESS => 'config/main'
210 config/main:
212 [% DEFAULT style = 'text'
214 section = template.section or 'home';
215 PROCESS config/site
217 + config/urls
218 + config/macros
219 + "config/style/$style"
220 + "config/section/$section"
221 + ...
222 %]
223 This allows me to set a single 'style' variable to control which config
225 file gets pre-processed to set my various style options (colours, img
226 paths, etc). For example:
227 config/style/basic:
229 [% style = {
231 name = style # save existing 'style' var as 'style.name'
232 # define various other style variables....
234 col = {
235 back => '#ffffff'
236 text => '#000000'
237 # ...etc...
238 }
239 logo = {
241 # ...etc...
242 }
243 # ...etc...
245 }
246 %]
247 Each source template can declare which section it's in via a META
249 directive:
250 [% META
252 title = 'General Information'
253 section = 'info'
254 %]
255 ...
256 This controls which section configuration file gets loaded to set
258 various other variables for defining the section title, menu, etc.
259 config/section/info:
261 [% section = {
263 name = section # save 'section' var as 'section.name'
264 title = 'Information'
265 menu = [ ... ]
266 # ...etc...
267 }
268 %]
269 This illustrates the basic principal but you can extend it to perform
271 pretty much any kind of per-document initialisation that you require.
272 Why do I get rubbish for my utf-8 templates?
274 First of all, make sure that your template files define a Byte Order
275 Mark <http://en.wikipedia.org/wiki/Byte_Order_Mark>
276 If you for some reason don't want to add BOM to your templates, you can
278 force Template to use a particular encoding (e.g. "utf8") for your
279 templates with the "ENCODING" option.
280 my $template = Template->new({
282 ENCODING => 'utf8'
283 });
284
286 Why is this FAQ so short?
287 Because we don't have anyone maintaining it.
288 Can I help?
290 Yes please :-)
291perl v5.38.0 2023-07-21 Template::FAQ(3)