conradwt

conradwt

Programming Phoenix 1.4: Add category_id to video table (page 121)

On page 103, we perform:

mix phx.gen.html Multimedia Video videos user_id:references:users \
url:string title:string description:text

The above code adds a field, user_id, to the videos tables.

video.ex:

defmodule Rumbl.Multimedia.Video do
  use Ecto.Schema
  import Ecto.Changeset

  schema "videos" do
    field :description, :string
    field :title, :string
    field :url, :string
    field :user_id, :id

    belongs_to :user, Rumbl.Accounts.User
    belongs_to :category, Rumbl.Multimedia.Category

    timestamps()
  end

  @doc false
  def changeset(video, attrs) do
    video
    |> cast(attrs, [:url, :title, :description, :category_id])
    |> validate_required([:url, :title, :description])
  end
end

One page 121, when I attempt to perform:

mix ecto.gen.migration add_category_id_to_video

I’m getting the following error message:

Compiling 1 file (.ex)

== Compilation error in file lib/rumbl/multimedia/video.ex ==
** (ArgumentError) field/association :user_id is already set on schema
    (ecto 3.5.8) lib/ecto/schema.ex:2056: Ecto.Schema.put_struct_field/3
    (ecto 3.5.8) lib/ecto/schema.ex:1809: Ecto.Schema.define_field/4
    (ecto 3.5.8) lib/ecto/schema.ex:1896: Ecto.Schema.__belongs_to__/4
    lib/rumbl/multimedia/video.ex:11: (module)
    (stdlib 3.14) erl_eval.erl:680: :erl_eval.do_apply/6
    (elixir 1.11.3) lib/kernel/parallel_compiler.ex:314: anonymous fn/4 in Kernel.ParallelCompiler.spawn_workers/7

Marked As Solved

conradwt

conradwt

I was able to resolve the issue by removing user_id field from the videos schema. It would be great if the book was updated to show the error caused by having both
field :user_id, :id and belongs_to :user, Rumbl.Accounts.User and providing a resolution.

Where Next?

Popular Pragmatic Bookshelf topics Top

yulkin
your book suggests to use Image.toByteData() to convert image to bytes, however I get the following error: "the getter ‘toByteData’ isn’t...
New
swlaschin
The book has the same “Problem space/Solution space” diagram on page 18 as is on page 17. The correct Problem/Solution space diagrams ar...
New
leba0495
Hello! Thanks for the great book. I was attempting the Trie (chap 17) exercises and for number 4 the solution provided for the autocorre...
New
New
dsmith42
Hey there, I’m enjoying this book and have learned a few things alredayd. However, in Chapter 4 I believe we are meant to see the “>...
New
Keton
When running the program in chapter 8, “Implementing Combat”, the printout Health before attack was never printed so I assumed something ...
New
New
SlowburnAZ
Getting an error when installing the dependencies at the start of this chapter: could not compile dependency :exla, "mix compile" failed...
New
dachristenson
I just bought this book to learn about Android development, and I’m already running into a major issue in Ch. 1, p. 20: “Update activity...
New
roadbike
From page 13: On Python 3.7, you can install the libraries with pip by running these commands inside a Python venv using Visual Studio ...
New

Other popular topics Top

PragmaticBookshelf
Stop developing web apps with yesterday’s tools. Today, developers are increasingly adopting Clojure as a web-development platform. See f...
New
dasdom
No chair. I have a standing desk. This post was split into a dedicated thread from our thread about chairs :slight_smile:
New
AstonJ
Just done a fresh install of macOS Big Sur and on installing Erlang I am getting: asdf install erlang 23.1.2 Configure failed. checking ...
New
PragmaticBookshelf
Author Spotlight Jamis Buck @jamis This month, we have the pleasure of spotlighting author Jamis Buck, who has written Mazes for Prog...
New
PragmaticBookshelf
Author Spotlight Mike Riley @mriley This month, we turn the spotlight on Mike Riley, author of Portable Python Projects. Mike’s book ...
New
New
First poster: AstonJ
Jan | Rethink the Computer. Jan turns your computer into an AI machine by running LLMs locally on your computer. It’s a privacy-focus, l...
New
PragmaticBookshelf
Escape callback hell and ship fast, clean code that reads as smoothly as it runs. Squash bugs and stamp out memory leaks with an intuitiv...
New
PragmaticBookshelf
Use advanced functional programming principles, practical Domain-Driven Design techniques, and production-ready Elixir code to build scal...
New
CommunityNews
Open-source implementation of the classic GTA engine now running directly in your browser. Experience the reVC technology demo on DOS.Zon...
New

Sub Categories: