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
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.
Popular Pragmatic Bookshelf topics
page 37
ANTLRInputStream input = new ANTLRInputStream(is);
as of ANTLR 4 .8 should be:
CharStream stream = CharStreams.fromStream(i...
New
Title: Hands-On Rust (Chapter 11: prefab)
Just played a couple of amulet-less games. With a bit of debugging, I believe that your can_p...
New
I can’t setup the Rails source code. This happens in a working directory containing multiple (postgres) Rails apps.
With:
ruby-3.0.0
s...
New
Hi @venkats,
It has been mentioned in the description of ‘Supervisory Job’ title that 2 things as mentioned below result in the same eff...
New
Dear Sophie.
I tried to do the “Authorization” exercise and have two questions:
When trying to plug in an email-service, I found the ...
New
I ran this command after installing the sample application:
$ cards add do something --owner Brian
And got a file not found error:
Fil...
New
Hi, I have just acquired Michael Fazio’s “Kotlin and Android Development” to learn about game programming for Android. I have a game in p...
New
I’m a newbie to Rails 7 and have hit an issue with the bin/Dev script mentioned on pages 112-113.
Iteration A1 - Seeing the list of prod...
New
AWDWR 7, page 152, page 153:
Hello everyone,
I’m a little bit lost on the hotwire part. I didn’t fully understand it.
On page 152 @rub...
New
Getting an error when installing the dependencies at the start of this chapter:
could not compile dependency :exla, "mix compile" failed...
New
Other popular topics
Design and develop sophisticated 2D games that are as much fun to make as they are to play. From particle effects and pathfinding to soci...
New
There’s a whole world of custom keycaps out there that I didn’t know existed!
Check out all of our Keycaps threads here:
https://forum....
New
Oh just spent so much time on this to discover now that RancherOS is in end of life but Rancher is refusing to mark the Github repo as su...
New
Hello everyone! This thread is to tell you about what authors from The Pragmatic Bookshelf are writing on Medium.
New
Author Spotlight
Mike Riley
@mriley
This month, we turn the spotlight on Mike Riley, author of Portable Python Projects. Mike’s book ...
New
New
Author Spotlight:
Peter Ullrich
@PJUllrich
Data is at the core of every business, but it is useless if nobody can access and analyze ...
New
If you’re getting errors like this:
psql: error: connection to server on socket “/tmp/.s.PGSQL.5432” failed: No such file or directory ...
New
Hello,
I’m a beginner in Android development and I’m facing an issue with my project setup. In my build.gradle.kts file, I have the foll...
New
Curious what kind of results others are getting, I think actually prefer the 7B model to the 32B model, not only is it faster but the qua...
New
Categories:
Sub Categories:
Popular Portals
- /elixir
- /rust
- /wasm
- /ruby
- /erlang
- /phoenix
- /keyboards
- /python
- /js
- /rails
- /security
- /go
- /swift
- /vim
- /clojure
- /java
- /emacs
- /haskell
- /svelte
- /onivim
- /typescript
- /kotlin
- /c-plus-plus
- /crystal
- /tailwind
- /react
- /gleam
- /ocaml
- /elm
- /flutter
- /vscode
- /ash
- /html
- /opensuse
- /zig
- /deepseek
- /centos
- /php
- /scala
- /react-native
- /lisp
- /textmate
- /sublime-text
- /nixos
- /debian
- /agda
- /django
- /deno
- /kubuntu
- /arch-linux
- /nodejs
- /spring
- /ubuntu
- /revery
- /manjaro
- /julia
- /diversity
- /lua
- /markdown
- /v









