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
Chrichton
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
brian-m-ops
#book-python-testing-with-pytest-second-edition Hi. Thanks for writing the book. I am just learning so this might just of been an issue ...
New
jgchristopher
“The ProductLive.Index template calls a helper function, live_component/3, that in turn calls on the modal component. ” Excerpt From: Br...
New
hgkjshegfskef
The test is as follows: Scenario: Intersecting a scaled sphere with a ray Given r ← ray(point(0, 0, -5), vector(0, 0, 1)) And s ← sphere...
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
jwandekoken
Book: Programming Phoenix LiveView, page 142 (157/378), file lib/pento_web/live/product_live/form_component.ex, in the function below: d...
New
dtonhofer
@parrt In the context of Chapter 4.3, the grammar Java.g4, meant to parse Java 6 compilation units, no longer passes ANTLR (currently 4....
New
SlowburnAZ
Getting an error when installing the dependencies at the start of this chapter: could not compile dependency :exla, "mix compile" failed...
New
New

Other popular topics Top

PragmaticBookshelf
Brace yourself for a fun challenge: build a photorealistic 3D renderer from scratch! In just a couple of weeks, build a ray tracer that r...
New
ohm
Which, if any, games do you play? On what platform? I just bought (and completed) Minecraft Dungeons for my Nintendo Switch. Other than ...
New
Exadra37
Please tell us what is your preferred monitor setup for programming(not gaming) and why you have chosen it. Does your monitor have eye p...
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
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
New
PragmaticBookshelf
Programming Ruby is the most complete book on Ruby, covering both the language itself and the standard library as well as commonly used t...
New
New
AstonJ
This is a very quick guide, you just need to: Download LM Studio: https://lmstudio.ai/ Click on search Type DeepSeek, then select the o...
New
Fl4m3Ph03n1x
Background Lately I am in a quest to find a good quality TTS ai generation tool to run locally in order to create audio for some videos I...
New

Sub Categories: