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https://github.com/SmartBear/ruby-handlebars

Pure Ruby library for Handlebars templates
https://github.com/SmartBear/ruby-handlebars

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Pure Ruby library for Handlebars templates

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README 

        
ruby-handlebars

===============



[![Build status](https://github.com/SmartBear/ruby-handlebars/actions/workflows/ci.yml/badge.svg)](https://github.com/SmartBear/ruby-handlebars/actions/workflows/ci.yml)

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[![Test Coverage](https://api.codeclimate.com/v1/badges/22dbe81de487cb27097c/test_coverage)](https://codeclimate.com/github/SmartBear/ruby-handlebars/test_coverage)



Pure Ruby library for [Handlebars](http://handlebarsjs.com/) template system.

The main goal of this library is to simplify the use of Ruby and Handlebars on Windows machine. If you do not have any need of working on Windows, take a look at [handlebars.rb](https://github.com/cowboyd/handlebars.rb) that uses the real Handlebars library.



Installing

----------



Simply run:



```shell

gem install ruby-handlebars

```



No need for libv8, ruby-racer or any JS related tool.



Using

-----



A very simple case:



```ruby



require 'ruby-handlebars'



hbs = Handlebars::Handlebars.new

hbs.compile("Hello {{name}}").call({name: 'world'})

# Gives: "Hello world", how original ...

```



You can also use partials:



```ruby

hbs.register_partial('full_name', "{{person.first_name}} {{person.last_name}}")

hbs.compile("Hello {{> full_name}}").call({person: {first_name: 'Pinkie', last_name: 'Pie'}})

# Gives: "Hello Pinkie Pie"

```



Partials support parameters:

```ruby

hbs.register_partial('full_name', "{{fname}} {{lname}}")

hbs.compile("Hello {{> full_name fname='jon' lname='doe'}}")

# Gives: "Hello jon doe"

```



You can also register inline helpers:



```ruby

hbs.register_helper('strip') {|context, value| value.strip}

hbs.compile("Hello {{strip name}}").call({name: '                       world     '})

# Will give (again ....): "Hello world"

```



or block helpers:



```ruby

hbs.register_helper('comment') do |context, commenter, block|

  block.fn(context).split("\n").map do |line|

    "#{commenter} #{line}"

  end.join("\n")

end



hbs.compile("{{#comment '//'}}My comment{{/comment}}").call

# Will give: "// My comment"

```



Note that in any block helper you can use an ``else`` block:



```ruby

hbs.register_helper('markdown') do |context, block, else_block|

  html = md_to_html(block.fn(context))

  html.nil? : else_block.fn(context) : html

end



template = [

  "{{#markdown}}",

  "  {{ description }}",

  "{{else}}",

  "  Description is not valid markdown, no preview available",

  "{{/markdown}}"

].join("\n")



hbs.compile(template).call({description: my_description})

# Output will depend on the validity of the 'my_description' variable

```



Default helpers:

----------------



Three default helpers are provided: ``each``, ``if`` and ``unless``.



The each helper let you walk through a list. You can either use the basic notation and referencing the current item as ``this``:



```

  {{#each items}}

    {{{ this }}}

  {{else}}

    No items

  {{/each}}

```



or the "as |name|" notation:



```

  {{#each items as |item| }}

    {{{ item }}}

  {{else}}

    No items

  {{/each}}

```



The ``if`` helper can be used to write conditionnal templates:



```

  {{#if my_condition}}

    It's ok

  {{else}}

    or maybe not

  {{/if}}

```



The ``unless`` helper works the opposite way to ``if``:



```

  {{#unless my_condition}}

    It's not ok

  {{else}}

    or maybe it is

  {{/unless}}

```



Currently, if you call an unknown helper, it will raise an exception. You can override that by registering your own version of the ``helperMissing`` helper. Note that only the name of the missing helper will be provided.



For example:



```ruby

hbs.register_helper('helperMissing') do |context, name|

  puts "No helper found with name #{name}"

end

```



Limitations and roadmap

-----------------------



This gem does not reuse the real Handlebars code (the JS one) and not everything is handled yet (but it will be someday ;) ):



 - the parser is not fully tested yet, it may complain with spaces ...

 - parsing errors are, well, not helpful at all



Aknowledgements

---------------



This gem would simply not exist if the handlebars team was not here. Thanks a lot for this awesome templating system.

Thanks a lot to @cowboyd for the [handlebars.rb](https://github.com/cowboyd/handlebars.rb) gem. We used it for a while and it's great (and as told at the beginning of the README, if you do not need any Windows support, use handlebars.rb instead ;) )



Thanks a lot to the contributors @mvz, @schuetzm and @stewartmckee for making it a way better Handlebars renderer :)