how to get session variable from params in rails (undefined method '*' for nil class

Question

In the first controller, I set my session variables:

def show
 @item = Item.find(params[:id])
 session[:item_id] = @item.id
 session[:amount] = params[:amount]
end

My view sets the amount with a form_tag:

<%= form_tag checkout_transaction_path, method: :get do %>
 <%= label_tag :amount %>
 <%= text_field :amount, placeholder: "Total bid amount", autofocus: true %>

 <%= submit_tag "submit" %>
<% end %>

The parameters that get sent with this form look like this:

Parameters: {"utf8"=>"✓", "amount"=>{"{:placeholder=>\"Total bid amount\", :autofocus=>true}"=>"1111"}, "commit"=>"Confirm offer", "id"=>"1"}

The second controller tries to assign the session variable to an instance variable.

def checkout
 @item = session[:item]
 @amount = session[:amount]
end

However, only @item is working. I try to multiply @amount * 0.10 but get this error: undefined method '*' for nil:NilClass

What causes that error? The submit params says it's being submitted, but maybe something is up with the way I try to retrieve it? session[:item_id] goes through perfectly.

Answer 1

You have issue here:

Parameters: {"utf8"=>"✓", "amount"=>{"{:placeholder=>\"Total bid amount\", :autofocus=>true}"=>"1111"}, "commit"=>"Confirm offer", "id"=>"sam-lipp-abandonment"}

In your parameters, you send amount parameters but in amount, you send HTML form "amount"=>{"{:placeholder=>\"Total bid amount\", :autofocus=>true}"=>"1111"}, but should send only value what you set in the amount form, and your amount parameters should looks like this example! "amount"=>"1"

So this means that your form doesn't work correctly! Try please replace your form on this one, and in a controller, you will get amount!

<%= form_for @new_item, url: checkout_transaction_path do |f| %>
 <%= f.label :amount %>
 <%= f.text_field :amount, placeholder: "Total bid amount", autofocus: true %>

 <%= submit_tag "submit" %>
<% end %>

OR the same code for form_tag

<%= form_tag checkout_transaction_path do %>
  <%= label_tag :amount %>
  <%= text_field_tag :amount, placeholder: "Total bid amount", autofocus: true %>

  <%= submit_tag "Submit Post" %>
<% end %>

The problem in your form can be here: you wrote text_field instead text_field_tag

Also for form_for form, you need to add in the controller in a method with variable what you will use in your form, for example, I'm using variable @new_item where from you call this form, something like this

def new
  @new_item = Item.new
end