Please how do you validate url inputs in your Phoenix projects forms?

Do you want to only validate the format or that the url really exists and returns something?

For now the url format is my only concern.

There is validate_format/4 where you can write a regexp for url validation, or something like this EctoFields.URL

So if I get it right, for some specific url I can combine validate_format/4 and EctoFields.URL.

Edit: If I don’t want to write some long regex like http://www\.youtube\.com\/(.+)|https://www\.youtube\.com\/(.+). ^^

Then something like this https://stackoverflow.com/questions/39041335/how-to-validate-url-in-elixir

If you want to validate a specific format for YouTube, then I think you will have to write a regexp for YouTube and handle different cases.

http://www\.youtube\.com\/(.+)|https://www\.youtube\.com\/(.+) is of course not so optimal. Could be done with http(s)?:\/\/www\.youtube\.com\/(.+).

Maybe also see this topic for inspiration Validating youtube link

I have a small lib called ex_url that parses URLs that you might find helpful.

Thanks to all the suggestions, finally I managed to write a really naive module for my url validation with Ecto.

My use case is very simple. In my project I want users to add their personal website url or their social link (facebook, twitter, etc.).

• for some personal website any valid url is okay.
• for some social link I need to ensure that the said social network name is included in a valid url.

All that validations are just for users browsing convenience. I won’t do anything with the urls apart displaying them on the owner profile page.

I choose the regex solution suggested by @egze because like that I won’t have to add any extra dependency to my project. Thanks also to @wolfiton that provided to me links to great resources on regex writing.

So see below a sample of the module

defmodule Easy.Url do
  @moduledoc """
  A module for url validation with Ecto
  """

  alias Ecto.{Changeset}
  import Changeset, only: [validate_format: 3]

  @before_tld "^(((ht|f)tp(s?))\://)?(www.|[a-zA-Z].)[a-zA-Z0-9\-\.]"
  @tld "([a-zA-Z])"
  @after_tld "(\:[0-9]+)*(/($|[a-zA-Z0-9\.\,\;\?\'\\\+&%\$#\=~_\-]+))*$"

  @regex Regex.compile!("#{@before_tld}+\.#{@tld}#{@after_tld}")

  @doc """
  Validate an url
  """
  def validate_url(changeset, field), do: validate_format(changeset, field, @regex)

  @doc """
  Validate an url for only some given top level domains
  """
  def validate_url(changeset, field, tld_list) do
    tld = Enum.join(tld_list, "|")

    case Regex.compile("#{@before_tld}+\.#{tld}#{@after_tld}") do
      {:ok, regex} ->
        validate_format(changeset, field, regex)

      _ ->
        validate_url(changeset, field)
    end
  end

  @doc """
  Validate an url while ensuring it contains a given domain
  """
  def validate_specific_url(changeset, field, domain) do
    changeset
    |> validate_url(field)
    |> validate_format(field, ~r/#{domain}/)
  end
end

Edit: Any suggestion is welcome of course.

Unfortunately your regex won’t parse some valid URLs like:

iex> Regex.match? @regex, "https://user:pass@my_site.com"          
false
iex> Regex.match? @regex, "https://my_site.com?tracking_token=some_token"   
false
iex> Regex.match? @regex, "https://my_site.com/" 

All of which can be parsed by the built-in URI module (ie no new dependency). For example:

iex> URI.parse "https://user:pass@my_site.com/"       
%URI{
  authority: "user:pass@my_site.com",
  fragment: nil,
  host: "my_site.com",
  path: "/",
  port: 443,
  query: nil,
  scheme: "https",
  userinfo: "user:pass"
}