Cannot invoke remote function Access.get/2 inside guards

david234

I have this form

                    <%= form_for @conn, Routes.admin_products_path(@conn, :create_product), [as: :create_product, id: "product-form", class: "mt-5 mb-5 login-input", method: :post, multipart: :true], fn f -> %>

                            <div class="form-group">
                                <%= text_input f, :name, placeholder: "Name", class: "form-control" %>
                            </div>
                            <div class="form-group">
                                <%= text_input f, :description, placeholder: "Description", class: "form-control" %>
                            </div>

                            <h4 class="card-title">Image Upload</h4>
                            <div class="form-group">
                                <%= file_input f,  :image_files, name: "create_product[images][]", multiple: true, class: "form-control", placeholder: "Upload Image" %>
                            </div>


                            <h4 class="card-title">Video Upload</h4>
                            <div class="form-group">
                                <%= file_input f, :video_files, name: "create_product[videos][]", multiple: true, class: "form-control", placeholder: "Upload Image" %>
                            </div>

                        <br/><br/>
                        <input type="submit" value="Save" class="btn btn-dark mb-2" />
                    <% end %>

I have this three function to filter and process through Guard

def create_product(conn, %{"create_product" => product_params}) when is_list(product_params["images"]) == true and is_list(product_params["videos"]) == true do


def create_product(conn, %{"create_product" => product_params}) when is_list(product_params["images"]) == true and is_list(product_params["videos"]) == false do


  def create_product(conn, %{"create_product" => product_params}) when is_list(product_params["images"]) == false and is_list(product_params["videos"]) == true do

Below is my inspect output

%{
  "description" => "sdfdf",
  "images" => [
    [
      %Plug.Upload{
        content_type: "image/jpeg",
        filename: "deuteronomy-2223-eggstransvestite-transvestism-cross-dressing-cult-prostitutes-lost-and-found-35-638.jpg",
        path: "/tmp/plug-1586/multipart-1586529347-447222130427589-1"
      }
    ]
  ],
  "name" => "Sony"
}

I can see this error is due to accessing product_params["images"].
Can anyone give me insight on how to solve this? Or is there any better way to filter this. Your help is greatly appreciated

4 comments

#code-style #learning-elixir

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2020-04-10 17:11:07 UTC

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benwilson512

Author of Craft GraphQL APIs in Elixir with Absinthe

Hi @david234, you need to write it like this:

def create_product(conn, %{"create_product" => %{"images" => images, "videos" => videos} = product_params)
  when is_list(images) and not is_list(videos) do

Basically, you need to pattern match out the values you want to use in the guards. Do note that the clause won’t match at all unless the product params include BOTH images and videos. If you need to handle them not being present at all, I’d consider doing this just inside the function body.

Post #1

david234

thanks @benwilson512 for your response. So i wrote like this

  def create_product(conn, %{"create_product" => %{"images" => images, "videos" => videos} = product_params}) when is_list(images) and is_list(videos) do

  def create_product(conn, %{"create_product" => %{"images" => images, "videos" => videos} = product_params}) when is_list(images)  do


  def create_product(conn, %{"create_product" => %{"images" => images, "videos" => videos} = product_params}) when is_list(videos) do


  def create_product(conn, %{"create_product" => product_params})  do

Do you think it is wise to do in this way? Or else I will write only one function inside that I will do all the filters. Which way is better?
I want to improve my coding standard so only asking this.

Post #2

benwilson512

Author of Craft GraphQL APIs in Elixir with Absinthe

Without know what you’re doing in the function body it’s hard to say. Personally I’d probably do something more like:

def create_product(conn, %{"create_product" => product_params})  do
  images = product_params["images"] || []
  videos = product_params["videos"] || []

But again, it depends on what you’re doing. If each of those clauses is a wildly different flow then go ahead with the pattern you have. If you’re just using it to normalize the data or something then I think that can be accomplished more succinctly by working with the parameters more individually.

Post #3