Mustache templates

A Dart library to parse and render mustache templates.

See the mustache manual for detailed usage information.

This library passes all mustache specification tests.

Example usage

import 'package:mustache/mustache.dart';

main() {
	var source = '''
	  {{# names }}
            <div>{{ lastname }}, {{ firstname }}</div>
	  {{/ names }}
	  {{^ names }}
	    <div>No names.</div>
	  {{/ names }}
	  {{! I am a comment. }}
	''';

	var template = new Template(source, name: 'template-filename.html');

	var output = template.renderString({'names': [
		{'firstname': 'Greg', 'lastname': 'Lowe'},
		{'firstname': 'Bob', 'lastname': 'Johnson'}
	]});

	print(output);
}

A template is parsed when it is created, after parsing it can be rendered any number of times with different values. A TemplateException is thrown if there is a problem parsing or rendering the template.

The Template contstructor allows passing a name, this name will be used in error messages. When working with a number of templates, it is important to pass a name so that the error messages specify which template caused the error.

By default all output from {{variable}} tags is html escaped, this behaviour can be changed by passing htmlEscapeValues : false to the Template constructor. You can also use a {{{triple mustache}}} tag, or a unescaped variable tag {{&unescaped}}, the output from these tags is not escaped.

Differences between strict mode and lenient mode.

Strict mode (default)

• Tag names may only contain the characters a-z, A-Z, 0-9, underscore, period and minus. Other characters in tags will cause a TemplateException to be thrown during parsing.

• During rendering, if no map key or object member which matches the tag name is found, then a TemplateException will be thrown.

Lenient mode

• Tag names may use any characters.
• During rendering, if no map key or object member which matches the tag name is found, then silently ignore and output nothing.

Nested paths

  var t = new Template('{{ author.name }}');
  var output = template.renderString({'author': {'name': 'Greg Lowe'}});

Partials - example usage

var partial = new Template('{{ foo }}', name: 'partial');

var resolver = (String name) {
   if (name == 'partial-name') { // Name of partial tag.
     return partial;
   }
};

var t = new Template('{{> partial-name }}', partialResolver: resolver);

var output = t.renderString({'foo': 'bar'}); // bar

Lambdas - example usage

var t = new Template('{{# foo }}');
var lambda = (_) => 'bar';
t.renderString({'foo': lambda}); // bar

var t = new Template('{{# foo }}hidden{{/ foo }}');
var lambda = (_) => 'shown'};
t.renderString({'foo': lambda); // shown

var t = new Template('{{# foo }}oi{{/ foo }}');
var lambda = (LambdaContext ctx) => '<b>${ctx.renderString().toUpperCase()}</b>';
t.renderString({'foo': lambda}); // <b>OI</b>

var t = new Template('{{# foo }}{{bar}}{{/ foo }}');
var lambda = (LambdaContext ctx) => '<b>${ctx.renderString().toUpperCase()}</b>';
t.renderString({'foo': lambda, 'bar': 'pub'}); // <b>PUB</b>

var t = new Template('{{# foo }}{{bar}}{{/ foo }}');
var lambda = (LambdaContext ctx) => '<b>${ctx.renderString().toUpperCase()}</b>';
t.renderString({'foo': lambda, 'bar': 'pub'}); // <b>PUB</b>

In the following example LambdaContext.renderSource(source) re-parses the source string in the current context, this is the default behaviour in many mustache implementations. Since re-parsing the content is slow, and often not required, this library makes this step optional.

var t = new Template('{{# foo }}{{bar}}{{/ foo }}');
var lambda = (LambdaContext ctx) => ctx.renderSource(ctx.source + ' {{cmd}}')};
t.renderString({'foo': lambda, 'bar': 'pub', 'cmd': 'build'}); // pub build