Mojo::Template

Section: User Contributed Perl Documentation (3)
Updated: 2018-11-22
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NAME

Mojo::Template - Perl-ish templates

SYNOPSIS

  use Mojo::Template;

  # Use Perl modules
  my $mt = Mojo::Template->new;
  say $mt->render(<<'EOF');
  % use Time::Piece;
  <div>
    % my $now = localtime;
    Time: <%= $now->hms %>
  </div>
  EOF

  # Render with arguments
  say $mt->render(<<'EOF', [1 .. 13], 'Hello World!');
  % my ($numbers, $title) = @_;
  <div>
    <h1><%= $title %></h1>
    % for my $i (@$numbers) {
      Test <%= $i %>
    % }
  </div>
  EOF

  # Render with named variables
  say $mt->vars(1)->render(<<'EOF', {title => 'Hello World!'});
  <div>
    <h1><%= $title %></h1>
    %= 5 + 5
  </div>
  EOF

DESCRIPTION

Mojo::Template is a minimalistic, fast, and very Perl-ish template engine, designed specifically for all those small tasks that come up during big projects. Like preprocessing a configuration file, generating text from heredocs and stuff like that.

See Mojolicious::Guides::Rendering for information on how to generate content with the Mojolicious renderer.

SYNTAX

For all templates strict, warnings, utf8 and Perl 5.10 features are automatically enabled.

  <% Perl code %>
  <%= Perl expression, replaced with result %>
  <%== Perl expression, replaced with XML escaped result %>
  <%# Comment, useful for debugging %>
  <%% Replaced with "<%", useful for generating templates %>
  % Perl code line, treated as "<% line =%>" (explained later)
  %= Perl expression line, treated as "<%= line %>"
  %== Perl expression line, treated as "<%== line %>"
  %# Comment line, useful for debugging
  %% Replaced with "%", useful for generating templates

Escaping behavior can be reversed with the ``auto_escape'' attribute, this is the default in Mojolicious ".ep" templates, for example.

  <%= Perl expression, replaced with XML escaped result %>
  <%== Perl expression, replaced with result %>

Mojo::ByteStream objects are always excluded from automatic escaping.

  % use Mojo::ByteStream 'b';
  <%= b('<div>excluded!</div>') %>

Whitespace characters around tags can be trimmed by adding an additional equal sign to the end of a tag.

  <% for (1 .. 3) { %>
    <%= 'Trim all whitespace characters around this expression' =%>
  <% } %>

Newline characters can be escaped with a backslash.

  This is <%= 1 + 1 %> a\
  single line

And a backslash in front of a newline character can be escaped with another backslash.

  This will <%= 1 + 1 %> result\\
  in multiple\\
  lines

A newline character gets appended automatically to every template, unless the last character is a backslash. And empty lines at the end of a template are ignored.

  There is <%= 1 + 1 %> no newline at the end here\

You can capture whole template blocks for reuse later with the "begin" and "end" keywords. Just be aware that both keywords are part of the surrounding tag and not actual Perl code, so there can only be whitespace after "begin" and before "end".

  <% my $block = begin %>
    <% my $name = shift; =%>
    Hello <%= $name %>.
  <% end %>
  <%= $block->('Baerbel') %>
  <%= $block->('Wolfgang') %>

Perl lines can also be indented freely.

  % my $block = begin
    % my $name = shift;
    Hello <%= $name %>.
  % end
  %= $block->('Baerbel')
  %= $block->('Wolfgang')

Mojo::Template templates get compiled to a Perl subroutine, that means you can access arguments simply via @_.

  % my ($foo, $bar) = @_;
  % my $x = shift;
  test 123 <%= $foo %>

The compilation of templates to Perl code can make debugging a bit tricky, but Mojo::Template will return Mojo::Exception objects that stringify to error messages with context.

  Bareword "xx" not allowed while "strict subs" in use at template line 4.
  2: </head>
  3: <body>
  4: % my $i = 2; xx
  5: %= $i * 2
  6: </body>
  template:4 (Mojo::Template::Sandbox)
  path/to/Mojo/Template.pm:123 (Mojo::Template)
  path/to/myapp.pl:123 (main)

ATTRIBUTES

Mojo::Template implements the following attributes.

auto_escape

  my $bool = $mt->auto_escape;
  $mt      = $mt->auto_escape($bool);

Activate automatic escaping.

  # "&lt;html&gt;"
  Mojo::Template->new(auto_escape => 1)->render("<%= '<html>' %>");

append

  my $code = $mt->append;
  $mt      = $mt->append('warn "Processed template"');

Append Perl code to compiled template. Note that this code should not contain newline characters, or line numbers in error messages might end up being wrong.

capture_end

  my $end = $mt->capture_end;
  $mt     = $mt->capture_end('end');

Keyword indicating the end of a capture block, defaults to "end".

  <% my $block = begin %>
    Some data!
  <% end %>

capture_start

  my $start = $mt->capture_start;
  $mt       = $mt->capture_start('begin');

Keyword indicating the start of a capture block, defaults to "begin".

  <% my $block = begin %>
    Some data!
  <% end %>

code

  my $code = $mt->code;
  $mt      = $mt->code($code);

Perl code for template if available.

comment_mark

  my $mark = $mt->comment_mark;
  $mt      = $mt->comment_mark('#');

Character indicating the start of a comment, defaults to "#".

  <%# This is a comment %>

compiled

  my $compiled = $mt->compiled;
  $mt          = $mt->compiled($compiled);

Compiled template code if available.

encoding

  my $encoding = $mt->encoding;
  $mt          = $mt->encoding('UTF-8');

Encoding used for template files, defaults to "UTF-8".

escape

  my $cb = $mt->escape;
  $mt    = $mt->escape(sub {...});

A callback used to escape the results of escaped expressions, defaults to ``xml_escape'' in Mojo::Util.

  $mt->escape(sub {
    my $str = shift;
    return reverse $str;
  });

escape_mark

  my $mark = $mt->escape_mark;
  $mt      = $mt->escape_mark('=');

Character indicating the start of an escaped expression, defaults to "=".

  <%== $foo %>

expression_mark

  my $mark = $mt->expression_mark;
  $mt      = $mt->expression_mark('=');

Character indicating the start of an expression, defaults to "=".

  <%= $foo %>

line_start

  my $start = $mt->line_start;
  $mt       = $mt->line_start('%');

Character indicating the start of a code line, defaults to "%".

  % $foo = 23;

name

  my $name = $mt->name;
  $mt      = $mt->name('foo.mt');

Name of template currently being processed, defaults to "template". Note that this value should not contain quotes or newline characters, or error messages might end up being wrong.

namespace

  my $namespace = $mt->namespace;
  $mt           = $mt->namespace('main');

Namespace used to compile templates, defaults to "Mojo::Template::SandBox". Note that namespaces should only be shared very carefully between templates, since functions and global variables will not be cleared automatically.

prepend

  my $code = $mt->prepend;
  $mt      = $mt->prepend('my $self = shift;');

Prepend Perl code to compiled template. Note that this code should not contain newline characters, or line numbers in error messages might end up being wrong.

replace_mark

  my $mark = $mt->replace_mark;
  $mt      = $mt->replace_mark('%');

Character used for escaping the start of a tag or line, defaults to "%".

  <%% my $foo = 23; %>

tag_start

  my $start = $mt->tag_start;
  $mt       = $mt->tag_start('<%');

Characters indicating the start of a tag, defaults to "<%".

  <% $foo = 23; %>

tag_end

  my $end = $mt->tag_end;
  $mt     = $mt->tag_end('%>');

Characters indicating the end of a tag, defaults to "%>".

  <%= $foo %>

tree

  my $tree = $mt->tree;
  $mt      = $mt->tree([['text', 'foo'], ['line']]);

Template in parsed form if available. Note that this structure should only be used very carefully since it is very dynamic.

trim_mark

  my $mark = $mt->trim_mark;
  $mt      = $mt->trim_mark('-');

Character activating automatic whitespace trimming, defaults to "=".

  <%= $foo =%>

unparsed

  my $unparsed = $mt->unparsed;
  $mt          = $mt->unparsed('<%= 1 + 1 %>');

Raw unparsed template if available.

vars

  my $bool = $mt->vars;
  $mt      = $mt->vars($bool);

Instead of a list of values, use a hash reference with named variables to pass data to templates.

  # "works!"
  Mojo::Template->new(vars => 1)->render('<%= $test %>!', {test => 'works'});

METHODS

Mojo::Template inherits all methods from Mojo::Base and implements the following new ones.

parse

  $mt = $mt->parse('<%= 1 + 1 %>');

Parse template into ``tree''.

process

  my $output = $mt->process;
  my $output = $mt->process(@args);
  my $output = $mt->process({foo => 'bar'});

Process previously parsed template and return the result, or a Mojo::Exception object if rendering failed.

  # Parse and process
  say Mojo::Template->new->parse('Hello <%= $_[0] %>')->process('Bender');

  # Reuse template (for much better performance)
  my $mt = Mojo::Template->new;
  say $mt->render('Hello <%= $_[0] %>!', 'Bender');
  say $mt->process('Fry');
  say $mt->process('Leela');

render

  my $output = $mt->render('<%= 1 + 1 %>');
  my $output = $mt->render('<%= shift() + shift() %>', @args);
  my $output = $mt->render('<%= $foo %>', {foo => 'bar'});

Render template and return the result, or a Mojo::Exception object if rendering failed.

  # Longer version
  my $output = $mt->parse('<%= 1 + 1 %>')->process;

  # Render with arguments
  say Mojo::Template->new->render('<%= $_[0] %>', 'bar');

  # Render with named variables
  say Mojo::Template->new(vars => 1)->render('<%= $foo %>', {foo => 'bar'});

render_file

  my $output = $mt->render_file('/tmp/foo.mt');
  my $output = $mt->render_file('/tmp/foo.mt', @args);
  my $output = $mt->render_file('/tmp/bar.mt', {foo => 'bar'});

Same as ``render'', but renders a template file.

DEBUGGING

You can set the "MOJO_TEMPLATE_DEBUG" environment variable to get some advanced diagnostics information printed to "STDERR".

  MOJO_TEMPLATE_DEBUG=1