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

telemachus
Python Testing With Pytest - Chapter 2, warnings for “unregistered custom marks” While running the smoke tests in Chapter 2, I get these...
New
GilWright
Working through the steps (checking that the Info,plist matches exactly), run the demo game and what appears is grey but does not fill th...
New
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
rmurray10127
Title: Intuitive Python: docker run… denied error (page 2) Attempted to run the docker command in both CLI and Powershell PS C:\Users\r...
New
fynn
This is as much a suggestion as a question, as a note for others. Locally the SGP30 wasn’t available, so I ordered a SGP40. On page 53, ...
New
jskubick
I found an issue in Chapter 7 regarding android:backgroundTint vs app:backgroundTint. How to replicate: load chapter-7 from zipfile i...
New
digitalbias
Title: Build a Weather Station with Elixir and Nerves: Problem connecting to Postgres with Grafana on (page 64) If you follow the defau...
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
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
Write Elixir tests that you can be proud of. Dive into Elixir’s test philosophy and gain mastery over the terminology and concepts that u...
New
Exadra37
I am thinking in building or buy a desktop computer for programing, both professionally and on my free time, and my choice of OS is Linux...
New
AstonJ
I ended up cancelling my Moonlander order as I think it’s just going to be a bit too bulky for me. I think the Planck and the Preonic (o...
New
AstonJ
If you are experiencing Rails console using 100% CPU on your dev machine, then updating your development and test gems might fix the issu...
New
AstonJ
Continuing the discussion from Thinking about learning Crystal, let’s discuss - I was wondering which languages don’t GC - maybe we can c...
New
AstonJ
If you get Can't find emacs in your PATH when trying to install Doom Emacs on your Mac you… just… need to install Emacs first! :lol: bre...
New
New
husaindevelop
Inside our android webview app, we are trying to paste the copied content from another app eg (notes) using navigator.clipboard.readtext ...
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
AstonJ
This is cool! DEEPSEEK-V3 ON M4 MAC: BLAZING FAST INFERENCE ON APPLE SILICON We just witnessed something incredible: the largest open-s...
New

Sub Categories: