Issue passing model instance to update action - ruby-on-rails

Question

In my Rails app I'm trying to create a form for updating model instance attributes with new info and am running into trouble.
When I hit submit on the edit form, the following error is thrown:
param is missing or the value is empty: product
And here's the code snippet it provides:
# all the attributes that must be submitted for the product to be listed
def product_params
params.require(:product).permit(:name, :price, :description)
end
end
I think the problem is that the model :product isn't getting passed from the edit form to the update action. Here's the form:
<h1>Edit your listing</h1>
<%= form_for edit_item_path(#product), url: {action: "update"} do |f| %>
<div><%= f.label :name %><br />
<%= f.text_field :name, :placeholder => "Name yourself" %>
</div>
<div><%= f.label :price %><br />
<%= f.number_field :price, :placeholder => "Name your price" %>
</div><br />
<div><%= f.label :description %><br />
<%= f.text_area :description, :cols => "50", :rows => "10", :placeholder => "Write a few sentences about the item you're listing. Is it in good condition? Are there any accessories included?"%>
</div>
<br />
<%= f.submit "Update listing" %>
<% end %>
Here are the edit and update actions in my products_controller:
def edit
#product = Product.find(params[:id])
end
def update
#product = Product.find(params[:id])
respond_to do |format|
if #product.update_attributes(product_params)
format.html {render :action => "show"}
else
format.html {render :action => "edit"}
end
end
end
Finally, my product routes
get "/products/new(.:format)" => "products#new", :as => "list_item"
post "/products/create(.:format)" => "products#create"
get "/products(.:format)" => "products#index"
get "/products/:id(.:format)" => "products#show"
get "/products/:id/edit(.:format)" => "products#edit", :as => "edit_item"
post "/products/:id/update(.:format)" => "products#update"
So anyone know what the problem is? Am I not passing the right info to the update action? If I'm not, what do I need to do to do it?

Answer 1

form_for
The problem you have is you're using form_for without any object
form_for generates an appropriate form tag and yields a form builder
object that knows the model the form is about. Input fields are
created by calling methods defined on the form builder, which means
they are able to generate the appropriate names and default values
corresponding to the model attributes, as well as convenient IDs, et
form_for helpers are primarily designed to give you a way to manage ActiveRecord objects:
<%= form_for #object do |f| %>
...
<% end %>
--
Fix
Everything inside this form block will have to work with the object in the form_for. As you have only used a path helper in your form_for method, it's not going to work as you hope.
You'll need to do this:
<%= form_for #product, url: {action: "update"} do |f| %>
This will ensure your form_for populates the object correctly. The error you have basically says your strong_params method is expecting this structure:
params => {
"product" => {
"name" => ____,
"price" => _____,
"description" => ______
}
}
As you've not included the #product object in your form_for, your params hash won't have the product key, thus causing your error. The fix is to populate the form_for element correctly

Answer 2

Replace
form_for edit_item_path(#product), url: {action: "update"}
with
form_for #product
which is similar to
form_for #product, as: :product, url: product_path(#product), method: :patch do |f|