MUSTACHE EXtended for Dart

The features of mustache with the addition of:

  • recasing variables
  • missing variables fulfillment function
  • hasVarName check

All with nested transitive variables handling


A simple usage example:

import 'package:mustachex/mustachex.dart';

main() async {
  var template = "{{#hasFoo}} this won't be rendered {{/hasFoo}}"
  '{{greeting_pascalCase}} {{world_pc}}!'
  '{{#hasBar}} This neither {{/hasBar}}';
  var vars = {'greeting': 'HELLO', 'foo': false};
  String fulfillmentFunction(MissingVariableException variable) {
    if (variable.varName == 'world') {
      return 'WORLD';
    } else {
      return 'UNIVERSE';

  var processor = MustachexProcessor(
      initialVariables: vars, missingVarFulfiller: fulfillmentFunction);
  var rendered = await processor.process(template);
  assert(rendered == 'Hello World!');

Features summary

Variables recasing

You can recase your variables by simply adding and _xxxCase termination:

{{ var_snakeCase }}{{ var_sc }}snake_case
{{ var_dotCase }}
{{ var_pathCase }}path/case
{{ var_paramCase }}param-case
{{ var_pascalCase }}{{ var_pc }}PascalCase
{{ var_headerCase }}Header-Case
{{ var_titleCase }}Title Case
{{ var_camelCase }}{{ var_cc }}camelCase
{{ var_sentenceCase }}Sentence case
{{ var_constantCase }}CONSTANT_CASE

Missing variables fullfillment

the fulfillment function should be of this kind:

String foo(MissingVariableException variable) => 'new_var_value_for_${variable.varName}';

and supposing the source of the missing exception was the following:

var src = '{{#parent1}}{{#parent2}}'

variable will have all this values:

variable.recasing; // 'paramCase'
variable.request; // 'var_paramCase'
variable.varName; // 'var'
variable.parentCollections; // ['parent1', 'parent2']
variable.humanReadableVariable; // "['parent1'],['parent2'],['var']"
variable.parentCollectionsWithVarName; // ['parent1', 'parent2', 'var']
variable.parentCollectionsWithRequest; // ['parent1', 'parent2', 'var_paramCase']

hasFoo guard

The mustache's sections that begins with has will automatically include a variable with the same name that will contain true or false depending on the context in which it was computed.

Supposing a mustache code of:

{{#hasFoo}}hasFoo was true{{/hasFoo}}
{{^hasFoo}}hasFoo was false{{/hasFoo}}

And the following JSON:

var json = {'foo': valueOfFoo}
valueOfFoohasFoo valuerendered mustache
nullfalsehasFoo was false
falsefalsehasFoo was false
[]falsehasFoo was false
{}falsehasFoo was false
''falsehasFoo was false
'a'truehasFoo was true
{'a':1}truehasFoo was true
['a']truehasFoo was true
truetruehasFoo was true


MUSTACHE EXtended library