hoeppner

hoeppner

From Ruby to Elixir — warning about invalid association when doing mix ecto.create (page 97)

Hi @sb8244,

I get a warning when I try to do the migrations on page 97 with mix ecto.create:

warning: invalid association sms_messages in schema PhoneApp.Conversations.Schema.Contact: associated schema PhoneApp.Conversations.Schema.SmsMessage does not have field contact_id
lib/phone_app/conversations/schema/contact.ex:1

I wanted to ask if this is because of the following:

The “SmsMessage” module has a clause that says schema "sms_messages" do. That is, the name of the module has the singular form, but the name of the schema is plural.
In case of the “Contact” module, the situation is reversed. It has an equivalent clause that says schema "contacts" do.

My confusion starts here:

The “SmsMessage” module refers to the contact s via belongs_to :contact (note the singular form in the token), while the “Contact” module refers to the SMS messages via has_many :sms_messages (note the plural).

Do the tokens’ (:contact, :sms_messages) forms (singular/plural) need to agree with the words in the schema clauses (i.e., schema "contacts" do and schema "sms_messages" do)?

Most Liked

sb8244

sb8244

Author of From Ruby to Elixir and Real-Time Phoenix

Which page are on on when you get this? One section of the chapter calls out that you’ll get a warning because we haven’t set up the other side of the association yet. In that case, the warning goes away a few pages later.

The plurality in the book is correct. Has many is plural, belongs to is singular. Schema modules are singular but the table name is plural (table name actually doesn’t matter.)

Where Next?

Popular Pragmatic Bookshelf topics Top

jeffmcompsci
Title: Design and Build Great Web APIs - typo “https://company-atk.herokuapp.com/2258ie4t68jv” (page 19, third bullet in URL list) Typo:...
New
jdufour
Hello! On page xix of the preface, it says there is a community forum "… for help if your’re stuck on one of the exercises in this book… ...
New
herminiotorres
Hi! I know not the intentions behind this narrative when called, on page XI: mount() |> handle_event() |> render() but the correc...
New
HarryDeveloper
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
brunogirin
When running tox for the first time, I got the following error: ERROR: InterpreterNotFound: python3.10 I realised that I was running ...
New
oaklandgit
Hi, I completed chapter 6 but am getting the following error when running: thread 'main' panicked at 'Failed to load texture: IoError(O...
New
gorkaio
root_layout: {PentoWeb.LayoutView, :root}, This results in the following following error: no “root” html template defined for PentoWeb...
New
mcpierce
@mfazio23 I’ve applied the changes from Chapter 5 of the book and everything builds correctly and runs. But, when I try to start a game,...
New
davetron5000
Hello faithful readers! If you have tried to follow along in the book, you are asked to start up the dev environment via dx/build and ar...
New
SlowburnAZ
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 Top

Devtalk
Hello Devtalk World! Please let us know a little about who you are and where you’re from :nerd_face:
New
AstonJ
A thread that every forum needs! Simply post a link to a track on YouTube (or SoundCloud or Vimeo amongst others!) on a separate line an...
New
New
AstonJ
You might be thinking we should just ask who’s not using VSCode :joy: however there are some new additions in the space that might give V...
New
AstonJ
In case anyone else is wondering why Ruby 3 doesn’t show when you do asdf list-all ruby :man_facepalming: do this first: asdf plugin-upd...
New
rustkas
Intensively researching Erlang books and additional resources on it, I have found that the topic of using Regular Expressions is either c...
New
AstonJ
Biggest jackpot ever apparently! :upside_down_face: I don’t (usually) gamble/play the lottery, but working on a program to predict the...
New
AstonJ
Was just curious to see if any were around, found this one: I got 51/100: Not sure if it was meant to buy I am sure at times the b...
New
AstonJ
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
mindriot
Ok, well here are some thoughts and opinions on some of the ergonomic keyboards I have, I guess like mini review of each that I use enoug...
New

Sub Categories: