jjabba

jjabba

Correctly deal with Ecto.Schema.Metadata for cascading delete

Im working with a database where table B has a foreign key (not null) referencing table A. A and B has a one-to-one relationship.

Furthermore the fk in Table B is created with the delete_all option

references(:A, on_delete: :delete_all)

most importantly, all deletions of b are done by deleting the corresponding a entry. Relying on the on the cascading delete functionality of the database.

Q:
Is there a nice way to implement a helper

 def delete_b(b) do
      # preload a,
      # delete a
      # return {:ok, b} with b.__meta__: #Ecto.Schema.Metadata<:deleted, "b">,
 end 

so that the b returned has the proper metadata state?

(I’ve resorted to a hack for now…

defp delete_b(b) do
    b = Repo.preload(b, :a)
    with {:ok, _deleted_a} <- Repo.delete(b.a) do
      meta = Kernel.struct(%Ecto.Schema.Metadata{}, %{state: :deleted, source: "b"})
      deleted_b = Kernel.struct(%B{}, %{id: b.id, __meta__: meta}))
      {:ok, deleted_b}
    else
      err -> err
    end
  end

)

Where Next?

Popular in Questions Top

Harrisonl
We have an ECS cluster with 4 services, where each task joins a single cluster, via discovery ECS discovery service. Currently when I de...
New
logicmason
Hi there, I'm working through my first release with elixir/phoenix. I've built a release with distillery and found that it crashes when I...
New
dotdotdotPaul
Okay, I'm having a heck of a time trying to figure out how to best handle the validation of belongs_to associations in Ecto. I'm sure I'...
New
ycv005
I have followed this StackOverflow post to install the specific version of Erlang. And When I am running mix ecto.setup then getting fol...
New
Werner
Hi, I’m using Ubuntu 18.04 and after updating to OTP-24.0 yesterday i have this warning when I run “mix local.hex”: 14:57:30.512 [warn] ...
New
nsuchy
Hi. I’ve noticed that Windows Powershell has it’s own IEX command and you cannot access Elixir’s IEX due to the conflict. This isn’t a cr...
New
makeitrein
Hey all, just started picking up Elixir last week and am writing a scraper as a learning project. Baby step #1 is extracting the number ...
New
mathew4509
I have a list say x = ["23gh", "56kh", "97mh"] I would like to pass each element to Val in each iteration. Say, in iteration 1 -------...
New
Mooodi
Given a string, how can I get access to its character by index? Enum.at("my_string", 2) doesn't work. Or rather, not char, but a substr...
New
joeerl
Hello again - after a longish gap I’ve decided I really must dig into Elixir and see what’s been happening here - so I have a few questio...
New

Other popular topics Top

SoCreat
i’m a new one to elixir which editor can i use vs code? or atom? Thanks! :smiley:
New
sergio
In Ruby, I can go: User.find_by(email: "foobar@email.com").update(email: "hello@email.com") How can I do something similar in Elixir? ...
New
bsollish-terakeet
Credo is smart enough to check for (something like) this: assert length(the_list) == 0 with this response: Checking if an enum is empt...
New
albydarned
Hello all! I am typing this post from my new MacBook Pro with the M1 chip. I’m loving it so far, and will probably use it as my daily dr...
New
vertexbuffer
Hello, can anybody help here..? I have a list of players and I what to delete an element, but every for loop the list is reverting to ori...
New
freewebwithme
Using vs code and installed ElixirLS: support and debugger. And I got an error popped up on start up says Failed to run ‘elixir’ comma...
New
danschultzer
None of the current solutions worked well for me, so I went ahead and built a user management system from scratch. This project took far...
548 27727 240
New
WestKeys
Currently suffering from paralysis by [HTTP client] analysis. This is rather unusual in Elixirland as there tends to be consensus on the ...
New
AstonJ
We’ve put together this wiki for Phoenix LiveView - please feel free to add any info you feel is worth including. What is Phoenix LiveV...
New
vrod
I am using the Starship cross-shell prompt – it seems pretty nice, but I get some errors: [WARN] - (starship::utils): Executing command ...
New

We're in Beta

About us Mission Statement