Validate

Validate incoming requests in an easy to reason-about way using Elixir.

🚨 Validate is an active WIP. Building mostly for fun/to satisfy my own needs on a project 🚨

Coming from languages like PHP and Node.js it can be difficult to reason about validating your requests using Ecto. This provides a simple data validation layer that aims to be extensible to allow for custom validation logic provided by the user.

Todo

• Give option to provide atoms in rule lists for simple validators to get rid of needing to import each one
• Test usage with mixed keys (:atoms and "strings")
• Add more out-of-the-box validators
• Provide documentation on custom validators
• i18n
• Support more input params than just maps

Installation

The package can be installed by adding validate to your list of dependencies in mix.exs:

def deps do
  [
    {:validate, "~> 0.2.2"}
  ]
end

Usage

defmodule MyApp.UserController do
  import Validate

  def create(conn, params) do
    case validate(params, create_rules) do
      {:ok, data} ->
        # ... create user
        # `data` is filtered to only the keys provided in `rules`

      {:error, errors} ->
        # errors is a map that matches the rules provided
        # in this case: %{ "username" => "required" }
        json(conn, errors)
    end
  end

  defp create_rules, do: %{
    "username": [:required],
  }
end

Validators

Required

Validates input is not:

• undefined
• null
• ""
• []
• {}

import Validate
data = %{ "username" => "" }
rules = %{
  "username" => [
    :required
  ]
}
validate(data, rules)
# {:error, %{ "username" => "required" }}

Optional

Does not continue with the rest of the validators if the value is not present or nil

• undefined
• null

import Validate
data = %{}
rules = %{
  "username" => [
    :optional,
    :string,
  ]
}
# value not present, so it's ok
validate(data, rules)
# {:ok, %{}}

import Validate
data = %{ "username" => 123 }
rules = %{
  "username" => [
    :optional,
    :string,
  ]
}
# value present, so it continues on to next validators
validate(data, rules)
# {:error, %{"username" => "not a string"}}

String

Validates input is a string

import Validate
data = %{
  "username" => 123
}
rules = %{
  "username" => [
    :string,
  ]
}
validate(data, rules)
# {:error, %{"username" => "not a string"}}

Number

Validates input is a number (float or int)

import Validate
data = %{
  "balance" => "very low"
}
rules = %{
  "balance" => [
    :number,
  ]
}
validate(data, rules)
# {:error, %{"balance" => "not a number"}}

List

Validates input is a list (array)

import Validate
data = %{
  "cities" => "saskatoon"
}
rules = %{
  "cities" => [
    :list,
  ]
}
validate(data, rules)
# {:error, %{"balance" => "not a list"}}