How can we get a record by id?

I was able to figure out that i can get one with:

Helpdesk.Support.get! Helpdesk.Support.Ticket, ticket.id

Helpdesk.Support.get! Helpdesk.Support.Ticket, ticket.id

but I would like to get it with:

Helpdesk.Api.read_support_ticket ticket.id

Helpdesk.Api.read_support_ticket ticket.id

This doesn't work:

{:error,
 %Ash.Error.Invalid{
   errors: [
     %Ash.Error.Invalid.MultipleResults{
       count: 2,
       at_least?: true,
       changeset: nil,
       query: nil,
       error_context: [],
       vars: [],
       path: [],
       stacktrace: #Stacktrace<>,
       class: :invalid
     }
   ],
   stacktraces?: true,
   changeset: nil,
   query: nil,
   error_context: [],
   vars: [],
   path: [],
   stacktrace: #Stacktrace<>,
   class: :invalid
 }}

{:error,
 %Ash.Error.Invalid{
   errors: [
     %Ash.Error.Invalid.MultipleResults{
       count: 2,
       at_least?: true,
       changeset: nil,
       query: nil,
       error_context: [],
       vars: [],
       path: [],
       stacktrace: #Stacktrace<>,
       class: :invalid
     }
   ],
   stacktraces?: true,
   changeset: nil,
   query: nil,
   error_context: [],
   vars: [],
   path: [],
   stacktrace: #Stacktrace<>,
   class: :invalid
 }}

My code:

defmodule Helpdesk.Api do

  require Ash.CodeInterface

  Ash.CodeInterface.define_interface(Helpdesk.Support, Helpdesk.Support.Ticket)
end

defmodule Helpdesk.Support.Ticket do
  
  use Ash.Resource,
    data_layer: Ash.DataLayer.Ets

  actions do
    defaults [:create, :read, :update, :destroy]

    create :open_support_ticket do
      accept [:subject]
    end

    read :read_support_ticket do
      # primary? true
      argument :id, :uuid do
        allow_nil? false
      end
      # filter [id: :id]
    end

  ## ommitted code ...

  code_interface do
    define :open_support_ticket, args: [:subject]
    define :read_support_ticket, action: :read_support_ticket, args: [:id], get?: true
    define :close_support_ticket, args: []
  end
end

defmodule Helpdesk.Api do

  require Ash.CodeInterface

  Ash.CodeInterface.define_interface(Helpdesk.Support, Helpdesk.Support.Ticket)
end

defmodule Helpdesk.Support.Ticket do
  
  use Ash.Resource,
    data_layer: Ash.DataLayer.Ets

  actions do
    defaults [:create, :read, :update, :destroy]

    create :open_support_ticket do
      accept [:subject]
    end

    read :read_support_ticket do
      # primary? true
      argument :id, :uuid do
        allow_nil? false
      end
      # filter [id: :id]
    end

  ## ommitted code ...

  code_interface do
    define :open_support_ticket, args: [:subject]
    define :read_support_ticket, action: :read_support_ticket, args: [:id], get?: true
    define :close_support_ticket, args: []
  end
end

10 Replies

waseigo•3y ago

Maybe you need to uncomment filter [id: :id] ?

ZachDaniel•3y ago

filter expr(id == ^arg(:id)) is the idiomatic way to do it You can read more about that in the expressions guide. You can also do it without adding arguments and filters to the action, by specifying get_by: [:id] on the code interface.

exadra37OP•3y ago

Thanks Zach, both work. Doesn't filter expr(id == ^arg(:id)) mean that it will first fetch all records from the database and then filter them to find the id I am looking for?

ZachDaniel•3y ago

Nope 🙂 Filters happen in the database

exadra37OP•3y ago

awesome I landed in the second suggestion

ZachDaniel•3y ago

If you’re familiar with ecto, we have our own expression syntax that we can put into database queries. Similar to what ecto can do.

exadra37OP•3y ago

My Elixie exposure isn't big, but I know ecto and used it in some pet apps, but I only do this time to time

ZachDaniel•3y ago

Gotcha. Yeah so expr is a limited syntax that supports specific things to run in the database (and sometimes not in the database, the framework takes care of that). You can read more about it in the expressions guide

exadra37OP•3y ago

I am thinking in using ASH to build a saas pet project, and my concerns are with queries performance and not being able to customize stuff as needed be them queries or other parts of the logic I really appreciate that you take the time to answers my questions. Thank you very much 🙂

ZachDaniel•3y ago

My pleasure 🙂 Ash is pretty optimized in a lot of ways (and I add optimizations regularly), but there are plenty of escape hatches where you can make it do w/e you want, including if you need to optimize something.

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How can we get a record by id?

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