Elixir Phoenix Plugs

The layout and details

• Routes

  • /
  • root of the app will eventually be an aggregate of incoming from Micro.Blog + our own feed (maybe)
  • /profile
  • ‘Settings’
  • this is where we’ll be able to add targets for our re-posting feature ‘echo’
  • add token keys and incorporate 3rd party API’s
  • /profile/posts
  • list of current users posts
  • /posting
  • this is the ‘editor’ with fields for title and content
  • Successful ‘post’ returns the user to an updated list of posts

Authorization

• now that we have authentication out of the way. Let’s deal with only that user can post to that users account.

Just do it already!

MB:postit> mix phx.gen.html Posting Post posts title:string content:text * creating lib/postit_web/controllers/post_controller.ex * creating lib/postit_web/templates/post/edit.html.eex * creating lib/postit_web/templates/post/form.html.eex * creating lib/postit_web/templates/post/index.html.eex * creating lib/postit_web/templates/post/new.html.eex * creating lib/postit_web/templates/post/show.html.eex * creating lib/postit_web/views/post_view.ex * creating test/postit_web/controllers/post_controller_test.exs * creating lib/postit/posting/post.ex * creating priv/repo/migrations/20190717045929_create_posts.exs * creating lib/postit/posting.ex * injecting lib/postit/posting.ex * creating test/postit/posting_test.exs * injecting test/postit/posting_test.exs Add the resource to your browser scope in lib/postit_web/router.ex: resources "/posts", PostController remember to update your repository by running migrations: $ mix ecto.migrate MB:postit>

That didn’t take long. Our first error. 😭

assign @current_user not available in eex template.

• so it looks like we’ve hit an error in the form that is created when we ran the generator.

• we’d forgotten to add the security plug to get for auth and the conditional in our Navbar is looking for current_user in order to render the login or logout buttons. happy that was simple.

  • The question is now, I have defined the secure function twice for both events and posts. Is there a place for those types of functions that i will be using in multiple controllers?
  • Option 1 seems to be helpers
  • Option 2 as found in Chris Bell Sharing Methods between controllers
  • Turns out the web.ex file has this cool macro __using__

def controller do quote do use Phoenix.Controller, namespace: PostitWeb import Plug.Conn import PostitWeb.Gettext alias PostitWeb.Router.Helpers, as: Routes end end

• Create a controller helper and add it in here!

  • I ended up with a ‘controller helper’ and accidently build a plug

Plugs: what did i learn [dot] info

• plugs feel conceptually a lot like express middleware, where it takes the connection or request and does a function on it, then returns the conn / request for the next plug or middleware

• There are two types of plugs in the Phoenix. They are module plugs and function plugs. We are going to cover both of them in this article.

  • module has init and call
  • HAHAH we had a function plug, I just had no idea that is what it was or called
• Where do we want the plug triggered?

• having stumbled into it in an effort to ‘DRY’ out our code. And really, there will probably be more controllers in our app over time and I feel like I have really hit the sweet spot of learning

  • question - how do i reuse a function in multiple controllers
  • start with a helper
  • add it to the web.ex for controller that is called as a macro for every controller to import the helper
  • use that helper function on a plug for the controller,
  • just make it a plug function or module

Alias vs Import

• What is the difference between alias and import ?

  • Docs! straight to the point doc alias
  • they are referred to as directives

  • alias use shorter name instead of the fully qualified name or prefix

    • is also lexically scoped, so it’s only available in the block / function you define it
    • “An alias in Elixir is a capitalized identifier (like String, Keyword, etc) which is converted to an atom during compilation. For instance, the String alias translates by default to the atom :"Elixir.String":”
  • require require this module in order to use it’s macros
  • import import functions from module so you don’t have to use the prefix
  • (macro) use invokes the custom code defined in that module as an extension point

Terms

• changeset

  • possibly an ecto term?

@doc false def changeset(post, attrs) do post |> cast(attrs, [:title, :content]) |> validate_required([:title, :content]) end

• conn

  • Short for … connection

• defp

  • Inside a module, we can define functions with def/2 and private functions with defp/2. A function defined with def/2 can be invoked from other modules while a private function can only be invoked locally.

Picks Resources

Elixir Casts Pheonix Contexts

Alchemist Camp

Elixir Phoenix Realworld

Pheonix Conn CheatSheet

indieweb

Micro [dot] Blog

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  • Email: jesse@jstoelm.com

• Jesse Tomchak

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