PlugParamsValidation

Provides functionality for validating parameters

Installation

def deps do
  [
    {:plug_params_validation, "~> 0.1.0"}
  ]
end

Usage

In your router:

import ParamsValidation

in order to get easy access to expect/1 function and :params_validation plug

Then, add the following plug. make sure it happens after the body parser plug:

plug :params_validation

Now, every endpoint with expect/1 will validate what ever you specify in expect example:

post "/register", expect(body_params: %{first_name: :string, last_name: :string, age: :integer}) do
  first_name = conn.body_params.first_name
  last_name = conn.body_params.last_name
  age = conn.body_params.num

  ...
end

if you would like to specify optional fields, you can pass a list to the :optional_body_params parameter in expect/1 optionals will be defaulted to nil. example:

post "/register", expect(body_params: %{first_name: :string, last_name: :string, age: :integer, phone: :string}, 
    optional_body_params: [:phone]) do
  first_name = conn.body_params.first_name
  last_name = conn.body_params.last_name
  age = conn.body_params.num

  phone = conn.body_params.phone || Phone.default_value 
  ...
end

this also works for GET requests: example:

get "/register/:name", expect(path_params: %{name: :string}) do
  # name can be used and trusted to be a string
  ...
end

You can mix between body_params optional_body_params and path_params inside POST, PUT...

When a request with bad parameters happens, the plug response with status code 400 and the following body:

{
    "errors": {
        "last_name": [
            "can't be blank"
        ],
        "age": [
            "can't be blank"
        ]
    }
}