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https://github.com/zotonic/cowmachine

Webmachine for Zotonic and Cowboy
https://github.com/zotonic/cowmachine

cowboy erlang erlang-library http-server webmachine zotonic

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Webmachine for Zotonic and Cowboy

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[![Test](https://github.com/zotonic/cowmachine/actions/workflows/test.yml/badge.svg)](https://github.com/zotonic/cowmachine/actions/workflows/test.yml)
[![Hex.pm version][hexpm version]][hexpm]
[![Hex.pm Downloads][hexpm downloads]][hexpm]
[![Hex.pm Documentation][hexdocs documentation]][hexdocs]
[![Erlang Versions][erlang version badge]][gh]
[![License][license]](https://www.apache.org/licenses/LICENSE-2.0)

# Cowmachine

Webmachine for Zotonic and Cowboy

This is an adaptation of https://github.com/webmachine/webmachine for the Cowboy web server.

Cowmachine is a request handler for Cowboy.

Main differences with Basho’s Webmachine are:

* Use cowboy instead of mochiweb for the http server
* Separate dispatching
* Simplified callbacks
* Single `process/4` callback for all http methods
* Caching of some callbacks (like `modified`)
* More streaming options for returned data
* Better support for range requests

## Installation

Cowmachine is at Hex, in your `rebar.config` file use:

```erlang
{deps, [
cowmachine
]}.
```

You can also use the direct Git url and use the development version:

```erlang
{deps, [
{cowmachine, {git, "https://github.com/zotonic/cowmachine.git", {branch, "master"}}}
]}.
```

## Calling Cowmachine

Cowmachine can be called from your Cowboy middleware:

```erlang
-spec execute(Req, Env) -> {ok, Req, Env} | {stop, Req}
when Req::cowboy_req:req(), Env::cowboy_middleware:env().
execute(Req, Env) ->
% Replace below with your own controller module and optionally wrap
% the request in your own request-context record or map.
EnvController = Env#{
cowmachine_controller => mycontroller
},
RequestContext = cowmachine_req:init_context(Req, EnvController, #{}),
% Set options for the cowmachine
Options = #{
on_request =>
fun(Ctx) ->
% Perform anything after initialization of your request
% Examples are checking special cookies, changing headers, etc.
Ctx
end,
on_welformed =>
fun(Ctx) ->
% Perform anything after well-formedness check of your request
% Examples are parsing the query args, or authentication
Ctx
end,
on_handled =>
fun(Ctx) ->
% Perform anything after processing, before sending the result.
Ctx
end
},
% Handle the request, returns updated Req and Env for next Cowboy middleware
cowmachine:request(RequestContext, Options).
```

Or just use the default Cowmachine middleware:

```erlang
#{
middlewares => [
% ... add your dispatcher middlware
cowmachine
],
request_timeout => 60000,
env => #{
% If no dispatcher, default to `mycontroller` as the cowmachine
% controller.
cowmachine_controller => mycontroller
}
}.
```

## Dispatching

You can use the [Zotonic Dispatch Compiler](https://github.com/zotonic/dispatch_compiler) to match your controller paths against the request.

## Controller

The controller provides the callbacks to handle the request.

The controller is an Erlang module implementing callback functions, only functions that return some non-default value need to be implemented.

For the controller callbacks and more documentation, check the [wiki pages](https://github.com/zotonic/cowmachine/wiki).

## Documentation generation

### Edoc

#### Generate public API
`rebar3 edoc`

#### Generate private API
`rebar3 as edoc_private edoc`

### ExDoc

`rebar3 ex_doc --logo doc/img/logo.png --output edoc -f html`

[hexpm]: https://hex.pm/packages/cowmachine
[hexpm version]: https://img.shields.io/hexpm/v/cowmachine.svg?style=flat-curcle "Hex version"
[hexpm downloads]: https://img.shields.io/hexpm/dt/cowmachine.svg?style=flat-curcle
[hexdocs documentation]: https://img.shields.io/badge/hex-docs-purple.svg?style=flat-curcle
[hexdocs]: https://hexdocs.pm/cowmachine
[gh]: https://github.com/zotonic/cowmachine/actions/workflows/test.yaml
[gh badge]: https://img.shields.io/github/workflow/status/zotonic/cowmachine/Test?style=flat-curcle
[erlang version badge]: https://img.shields.io/badge/Supported%20Erlang%2FOTP-22.0%20to%2024.0-blue.svg?style=flat-curcle
[license]: https://img.shields.io/badge/License-Apache_2.0-blue.svg?logo=apache&logoColor=red "Apache 2.0"