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N2O templates. Static HTML

сб 02 мая 2020, tags: ErlangN2OTutorial

Re-posting from 2014-09-24

It's a time to learn more N2O. In this article we will show how to render templates using different techniques:

  • Static html template
  • N2O record-based templates
  • Erlydtl templates


For this example, we will use a project we have created in the previous tutorial. A directory structure will be like that:

example|master⚡ ⇒ tree .
├── apps
│   └── web
│       ├── ebin
│       └── src
│           ├── index.erl
│           ├── routes.erl
│           ├──
│           ├── web_app.erl
│           └── web_sup.erl
├── deps
├── rebar
└── rebar.config

Static html

This method will be useful in case if you want to have some static files, but do not want to run a web-server on the development machine.

For routing and handling requests N2O is using the cowboy web server, so rendering a static html file basically will be through configuring a cowboy handler. For this step we should create an HTML file in the priv directory of our web app and add route to the routes map.

Create a directory and file:

$ mkdir apps/web/priv                 # create a 'priv' directory
$ touch apps/web/priv/example.html    # create an HTML file
$ echo "<h1>Example page</h1>" > apps/web/priv/example.html # insert content

As you remember we defined routes in web_sup:rules/0 function. So let's go and add our example page to the routes map.

$ vim apps/web/src/web_sup.erl
rules() ->
    [{'_', [
       {"/example",                                    % handling url
         cowboy_static,                                % cowboy handler
         {priv_file, web, "example.html",              % a place where the file is saved
             {mimetypes, {<<"text">>, <<"html">>, []}} % mime type
       {'_', n2o_cowboy, []}

A 'cowboy_router:compile/1' is accepting a list of tuples with domain + routes definitions.

Well, it's done. Let's compile our project, run and check it out in browser by http://localhost:8002/example url.

$ ./rebar compile
$ erl -name "web@$(hostname)" -pa deps/*/ebin -pa apps/*/ebin -boot start_sasl -s web_app start

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