1Template::FAQ(3)      User Contributed Perl Documentation     Template::FAQ(3)
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NAME

6       Template::FAQ - Frequently Asked Questions about the Template Toolkit
7

Template Toolkit Language

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
13           [% a = b IF c %]
14
15       The parser interprets it as an attempt to set "a" to the result of "b
16       IF c", like this:
17
18           [% a = (b IF c) %]
19
20       If you want to set "a = b" only if "c" is true, then do this instead:
21
22           [% SET a = b IF c %]
23
24       The explicit "SET" keyword gives the parser the clue it needs to do the
25       right thing.
26
27       NOTE: this will be fixed in TT3
28
29   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
33           [% stag = "[\%"
34              etag = "%\]"
35           %]
36
37       and then:
38
39           [% stag; 'hello'; etag %]
40
41       Or you can use the "TAGS" directive, like so:
42
43           [% TAGS [- -] %]
44           [- INCLUDE foo -]   # is a directive
45           [% INCLUDE foo %]   # not a directive
46
47   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
53           [% FOREACH key = product.keys %]
54              [% key %] => [% product.$key %]
55           [% END %]
56

Plugins

58   How do I get the Table plugin to order data across rather than down?
59       Order the data into rows:
60
61           Steve     Karen     Jeff
62           Brooklyn  Nantucket Fairfax
63           NY        MA        VA
64
65           [% USE table(data, rows=3) %]
66
67       Then ask for each column
68
69           [% FOREACH column = table.cols %]
70
71       And then print each item in the column going across the output rows
72
73           [% FOREACH item = column %]
74               <td>[% item %]</td>
75           [% END %]
76
77   Accessing Cookies
78       Jeff Boes <jboes@nexcerpt.com> asks:
79
80           Does anyone have a quick-n-dirty approach to accessing
81           cookies from templates?
82
83       Jonas Liljegren answers:
84
85           [% USE CGI %]
86
87           <p>The value is [% CGI.cookie('cookie_name') | html %]
88

Extending the Template Toolkit

90   Can I serve templates from a database?
91       Short answer: yes, Chris Nandor has done this for Slash.  You need to
92       subclass Template::Provider.  See the mailing list archives for further
93       info.
94
95   Can I fetch templates via http?
96       To do the job properly, you should subclass Template::Provider to
97       "Template::Provider::HTTP" and use a "PREFIX_MAP" option to bind the
98       "http" template prefix to that particular provider (you may want to go
99       digging around in the Changes file around version 2.01 for more info on
100       "PREFIX_MAP" - it may not be properly documented anywhere else...yet!).
101       e.g.
102
103           use Template::Provider::HTTP;
104
105           my $file = Template::Provider( INCLUDE_PATH => [...] );
106           my $http = Template::Provider::HTTP->new(...);
107           my $tt2  = Template->new({
108               LOAD_TEMPLATES => [ $file, $http ],
109               PREFIX_MAP => {
110                   file    => '0',     # file:foo.html
111                   http    => '1',     # http:foo.html
112                   default => '0',     # foo.html => file:foo.html
113               }
114           });
115
116       Now a template specified as:
117
118           [% INCLUDE foo %]
119
120       will be served by the 'file' provider (the default).  Otherwise you can
121       explicitly add a prefix:
122
123           [% INCLUDE file:foo.html %]
124           [% INCLUDE http:foo.html %]
125           [% INCLUDE http://www.xyz.com/tt2/header.tt2 %]
126
127       This same principal can be used to create a DBI template provider.
128       e.g.
129
130           [% INCLUDE dbi:foo.html %]
131
132       Alas, we don't yet have a DBI provider as part of the Template Toolkit.
133       There has been some talk on the mailing list about efforts to develop
134       DBI and/or HTTP providers but as yet no-one has stepped forward to take
135       up the challenge...
136
137       In the mean time, Craig Barrat's post from the mailing list has some
138       useful pointers on how to achieve this using existing modules.  See
139       <http://tt2.org/pipermail/templates/2001-May/000954.html>
140

Miscellaneous

142   How can I find out the name of the main template being processed?
143       The "template" variable contains a reference to the Template::Document
144       object for the main template you're processing (i.e. the one provided
145       as the first argument to the Template process() method).  The "name"
146       method returns its name.
147
148           [% template.name %]     # e.g. index.html
149
150   How can I find out the name of the current template being processed?
151       The "template" variable always references the main template being
152       processed.  So even if you call [% INCLUDE header %], and that calls [%
153       INCLUDE menu %], the "template" variable will be unchanged.
154
155       index.html:
156
157           [% template.name  %]     # index.html
158           [% INCLUDE header %]
159
160       header:
161
162           [% template.name  %]     # index.html
163           [% INCLUDE menu   %]
164
165       menu:
166
167           [% template.name  %]     # index.html
168
169       In contrast, the "component" variable always references the current
170       template being processed.
171
172       index.html
173
174           [% component.name %]     # index.html
175           [% INCLUDE header %]
176
177       header:
178
179           [% component.name %]     # header
180           [% INCLUDE menu   %]
181
182       menu:
183
184           [% component.name  %]     # menu
185
186   How do I print the modification time of the template or component?
187       The "template" and "component" variables reference the main template
188       and the current template being processed (see previous questions).  The
189       "modtime" method returns the modification time of the corresponding
190       template file as a number of seconds since the Unix epoch (00:00:00 GMT
191       1st January 1970).
192
193       This number doesn't mean much to anyone (except perhaps serious Unix
194       geeks) so you'll probably want to use the Date plugin to format it for
195       human consumption.
196
197           [% USE Date %]
198           [% template.name %] last modified [% Date.format(template.modtime) %]
199
200   How can I configure variables on a per-request basis?
201       One easy way to achieve this is to define a single "PRE_PROCESS"
202       template which loads in other configuration files based on variables
203       defined or other conditions.
204
205       For example, my setup usually looks something like this:
206
207           PRE_PROCESS => 'config/main'
208
209       config/main:
210
211           [%  DEFAULT  style   = 'text'
212                        section =  template.section or 'home';
213
214               PROCESS  config/site
215                     +  config/urls
216                     +  config/macros
217                     + "config/style/$style"
218                     + "config/section/$section"
219                     + ...
220           %]
221
222       This allows me to set a single 'style' variable to control which config
223       file gets pre-processed to set my various style options (colours, img
224       paths, etc).  For example:
225
226       config/style/basic:
227
228           [%  style = {
229                   name = style    # save existing 'style' var as 'style.name'
230
231                   # define various other style variables....
232                   col = {
233                       back => '#ffffff'
234                       text => '#000000'
235                           # ...etc...
236                   }
237
238                   logo = {
239                           # ...etc...
240                   }
241
242                   # ...etc...
243               }
244           %]
245
246       Each source template can declare which section it's in via a META
247       directive:
248
249         [% META
250              title   = 'General Information'
251              section = 'info'
252         %]
253         ...
254
255       This controls which section configuration file gets loaded to set
256       various other variables for defining the section title, menu, etc.
257
258       config/section/info:
259
260           [%  section = {
261                   name   = section  # save 'section' var as 'section.name'
262                   title  = 'Information'
263                   menu   = [ ... ]
264                   # ...etc...
265               }
266           %]
267
268       This illustrates the basic principal but you can extend it to perform
269       pretty much any kind of per-document initialisation that you require.
270
271   Why do I get rubbish for my utf-8 templates?
272       First of all, make sure that your template files define a Byte Order
273       Mark <http://en.wikipedia.org/wiki/Byte_Order_Mark>
274
275       If you for some reason don't want to add BOM to your templates, you can
276       force Template to use a particular encoding (e.g. "utf8") for your
277       templates with the "ENCODING" option.
278
279           my $template = Template->new({
280               ENCODING => 'utf8'
281           });
282

Questions About This FAQ

284   Why is this FAQ so short?
285       Because we don't have anyone maintaining it.
286
287   Can I help?
288       Yes please :-)
289
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292perl v5.32.0                      2020-07-28                  Template::FAQ(3)
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