borybar

borybar

Hi,

I am displaying users cpm based on their submitted form. It all works until I am creating a new user who doesn’t have such cpm yet. Then I get an error. I understand that I need to use case in which I check either there is a cpm or not, if not I return a link to needed form. I was wondering how to do it, as I am not sure what I should write in such case.

My page_controller:

def index(conn, _params, current_user) do
   user = current_user.id
   user_pps = Cpm.list_user_pp(current_user)
   user_pp = Cpm.get_user_pp!(current_user, user)
   user_bmr = Bmr.bmr_for_user(user_pp)
   user_cpm = Float.floor(Bmr.cpm_for_user(user_pp, user_bmr))
   
   case user_cpm do
     {:ok} -> returns first cpm
     {:error} -> returns a link to a form
   render(conn, "index.html", user: user, userp_pps: user_pps, user_cpm: user_cpm)

Thanks for help!

Showing Posts 1 to 9

kokolegorille

kokolegorille

You can always redirect in case there is no user_cpm.

Another way is to use a conditional in the template… like this.

if assigns[:user_cpm] do
  -> usual stuff when there is a user_cpm
else
  -> display link to form
end

You case miss an end :slight_smile:

borybar

borybar OP

Thanks for the reply!

What if I don’t want to redirect from start? I want to keep a user on the front page so he has access to different things, only if he wants to he can click a button to redirect to my form

kokolegorille

kokolegorille

Then try the code I put in my last post :slight_smile:

borybar

borybar OP

I have tried your recommendation but I guess I am doing something wrong. I will be very grateful for your help.

This is my template now:

<h2>Your Profile</h2>
          <ul>
          <%= if @current_user do %>
            <%= if assigns[:user_cpm] do %>
              -> <h2 style = "position:absolute; left:350px; top:275px;">User CPM: <br> <%= @user_cpm %></h2>
            <% else %>
              -> <%= link "Create Cpm", to: Routes.physical_profile_path(@conn, :new) %>%
          <% end %>
            <li>
              <%= link "Your Cpm", to: Routes.physical_profile_path(@conn, :index) %>
            </li> 
            <li>
              <%= link "Users", to: Routes.user_path(@conn, :index) %>
            </li>
            <li>
              <%= link "Foods", to: Routes.food_path(@conn, :index) %> 
            </li>
          <% end %>
          </ul>

What I get when I try to visit my main page is:


UndefinedFunctionError at GET /
function nil.id/0 is undefined

borybar

borybar OP

I suspect that it’s not even getting to my user_cpm variable as it doesn’t have a value in user variable in my controller as there is no users in db.

kokolegorille

kokolegorille

Try replacing @current_user with assigns[:current_user]

The first will fail if not set, the second will return nil.

You cannot use variable that have not been set.

If current_user is not set, it will fail with the error You see…

borybar

borybar OP

So if I can’t use variable that have not been set yet, what can I do? Use case?

kokolegorille

kokolegorille

No, use assigns[:current_user] in the template…

or test that the value exists.

You cannot use current_user.id if it is not set.

borybar

borybar OP

Thank you for help. I managed to resolve my issue by using case

— All posts loaded —

Where Next? Top

Trending in Questions Top

katta
I having some trouble figuring out if I have set myself too strict of standards for my production server. Currently I can handle 75% of r...
New
achenet
Hello, I’m trying to build a basic Phoenix web-app, and I’d like to use Tailwind. However, when I launch mix phx.server, I get an error...
New
kpanic
Hi everyone, I am toying with the idea of building a “match maker” for giving personal help to people that wants to start coding. I sta...
New
Cxx-mlr
I’m working on a small exercise involving update_in/3, and I came up with this solution: data = %{ name: "Periodic Table", category:...
New
ChrisAmelia
I’ve got trouble wrapping my head around the order in which functions are called in this snippet (from Phoenix’s authentication): toke...
New
dillonoconnor
Is there any way to avoid the Hologram compiler running when using iex? It seems like the front-end code could potentially be disregarded...
New
thiagogsr
** (ArgumentError) expected :max_attempts to be a positive integer, got: {:@, [line: 10, column: 19], [{:max_attempts, [line: 10, column:...
New

Other Trending Topics Top

GenericJam
Edit: 2026 May 15 - This post is archived. Mob is alive!! Main docs: mob v0.7.11 — Documentation A bit of explanation for the slightly c...
New
mudasobwa
I am happy to introduce the very α version of the new programming language compiled to BEAM. Welcome Cure. It has literally three kille...
New
garrison
Hobbes is a low-level distributed database for the Elixir programming language. Hobbes provides a simple, safe, and scalable storage lay...
New
budgie
A little off-topic, but I feel like people here have a good head on their shoulders. I used to be quite good at making software. Was luc...
New
KristerV
Hey. Is there anyone here who creates agents in their apps? Not talking about using agents, but creating them. I’m finding it pretty diff...
New
mcass19
ExRatatui lets you cook up rich terminal UIs in Elixir, powered by Rust’s ratatui via Rustler NIFs. Build interactive terminal applicatio...
New

We're in Beta

About us Mission Statement

Options

Thread Display Mode




Thread Preview

Skip Thread Previews