# Maxwell
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Maxwell is an HTTP client that provides a common interface over [:httpc](http://erlang.org/doc/man/httpc.html), [:ibrowse](https://github.com/cmullaparthi/ibrowse), [:hackney](https://github.com/benoitc/hackney).
## Getting Started
The simplest way to use Maxwell is by creating a module which will be your API wrapper, using `Maxwell.Builder`:
```elixir
defmodule GitHubClient do
# Generates `get/1`, `get!/1`, `patch/1`, `patch!/1` public functions
# You can omit the list and functions for all HTTP methods will be generated
use Maxwell.Builder, ~w(get patch)a
# For a complete list of middlewares, see the docs
middleware Maxwell.Middleware.BaseUrl, "https://api.github.com"
middleware Maxwell.Middleware.Headers, %{"content-type" => "application/vnd.github.v3+json", "user-agent" => "zhongwenool"}
middleware Maxwell.Middleware.Opts, connect_timeout: 3000
middleware Maxwell.Middleware.Json
middleware Maxwell.Middleware.Logger
# adapter can be omitted, and the default will be used (currently :ibrowse)
adapter Maxwell.Adapter.Hackney
# List public repositories for the specified user.
def user_repos(username) do
"/users/#{username}/repos"
|> new()
|> get()
end
# Edit owner repositories
def edit_repo_desc(owner, repo, name, desc) do
"/repos/#{owner}/#{repo}"
|> new()
|> put_req_body(%{name: name, description: desc})
|> patch()
end
end
```
`Maxwell.Builder` injects functions for all supported HTTP methods, in two flavors, the first (e.g. `get/1`) will
return `{:ok, Maxwell.Conn.t}` or `{:error, term, Maxwell.Conn.t}`. The second (e.g. `get!/1`) will return
`Maxwell.Conn.t` *only* if the request succeeds and returns a 2xx status code, otherwise it will raise `Maxwell.Error`.
The same functions are also exported by the `Maxwell` module, which you can use if you do not wish to define a wrapper
module for your API, as shown below:
```elixir
iex(1)> alias Maxwell.Conn
iex(2)> Conn.new("http://httpbin.org/drip") |>
Conn.put_query_string(%{numbytes: 25, duration: 1, delay: 1, code: 200}) |>
Maxwell.get
{:ok,
%Maxwell.Conn{method: :get, opts: [], path: "/drip",
query_string: %{code: 200, delay: 1, duration: 1, numbytes: 25},
req_body: nil, req_headers: %{}, resp_body: '*************************',
resp_headers: %{"access-control-allow-credentials" => "true",
"access-control-allow-origin" => "*",
"connection" => "keep-alive",
"content-length" => "25",
"content-type" => "application/octet-stream",
"date" => "Sun, 18 Dec 2016 14:32:38 GMT",
"server" => "nginx"}, state: :sent, status: 200,
url: "http://httpbin.org"}}
```
There are numerous helper functions for the `Maxwell.Conn` struct. See it's module docs
for a list of all functions, and detailed info about how they behave.
## Installation
1. Add maxwell to your list of dependencies in `mix.exs`:
```ex
def deps do
[{:maxwell, "~> 2.3"}]
end
```
2. Ensure maxwell has started before your application:
```ex
def application do
[applications: [:maxwell]] # also add your adapter(ibrowse, hackney)
end
```
## Adapters
Maxwell has support for different adapters that do the actual HTTP request processing.
### httpc
Maxwell has built-in support for the [httpc](http://erlang.org/doc/man/httpc.html) Erlang HTTP client.
To use it simply place `adapter Maxwell.Adapter.Httpc` in your API client definition.
### ibrowse
Maxwell has built-in support for the [ibrowse](https://github.com/cmullaparthi/ibrowse) Erlang HTTP client.
To use it simply place `adapter Maxwell.Adapter.Ibrowse` in your API client definition.
**NOTE**: Remember to include `:ibrowse` in your applications list.
### hackney
Maxwell has built-in support for the [hackney](https://github.com/benoitc/hackney) Erlang HTTP client.
To use it simply place `adapter Maxwell.Adapter.Hackney` in your API client definition.
**NOTE**: Remember to include `:hackney` in your applications list.
## Built-in Middleware
### Maxwell.Middleware.BaseUrl
Sets the base url for all requests.
### Maxwell.Middleware.Headers
Sets default headers for all requests.
### Maxwell.Middleware.HeaderCase
Enforces that all header keys share a specific casing style, e.g. lower-case,
upper-case, or title-case.
### Maxwell.Middleware.Opts
Sets adapter options for all requests.
### Maxwell.Middleware.Rels
Decodes rel links in the response, and places them in the `:rels` key of the `Maxwell.Conn` struct.
### Maxwell.Middleware.Logger
Logs information about all requests and responses. You can set `:log_level` to log the information at that level.
### Maxwell.Middleware.Json
Encodes all requests as `application/json` and decodes all responses as `application/json`.
### Maxwell.Middleware.EncodeJson
Encodes all requests as `application/json`.
### Maxwell.Middleware.DecodeJson
Decodes all responses as `application/json`.
**NOTE**: The `*Json` middlewares require [Poison](https://github.com/devinus/poison) as dependency, versions 2.x and 3.x are supported.
You may provide your own encoder/decoder by providing the following options:
```ex
# For the EncodeJson module
middleware Maxwell.Middleware.EncodeJson,
encode_content_type: "text/javascript",
encode_func: &other_json_lib.encode/1]
# For the DecodeJson module
middleware Maxwell.Middleware.DecodeJson,
decode_content_types: ["yourowntype"],
decode_func: &other_json_lib.decode/1]
# Both sets of options can be provided to the Json module
```
## Custom Middlewares
Take a look at the [Maxwell.Middleware](https://github.com/zhongwencool/maxwell/blob/master/lib/maxwell/middleware/middleware.ex) for more information
on the behaviour. For example implementations take a look at any of the middleware modules in the repository.
## Contributing
Contributions are more than welcome!
Check the issues tracker for anything marked "help wanted", and post a comment that you are planning to begin working on the issue. We can
then provide guidance on implementation if necessary.
## License
See the [LICENSE](https://github.com/zhongwencool/maxwell/blob/master/LICENSE) file for license rights and limitations (MIT).
