Ash Elixir•2y ago

How to have a "virtual field" in a resource based from another resource?

I have a Organization resource that has a many to many relationship with my User resource. That relationship is defined by this field in the Organization resource:

    many_to_many :users, User do
      through UserOrganization

      source_attribute_on_join_resource :organization_id
      destination_attribute_on_join_resource :user_id
    end

    many_to_many :users, User do
      through UserOrganization

      source_attribute_on_join_resource :organization_id
      destination_attribute_on_join_resource :user_id
    end

The UserOrganization resource has a special attribute inside of which defined if the user is an admin inside that organization:

defmodule UserOrganization do
  use Ash.Resource, data_layer: AshPostgres.DataLayer

  attributes do
    attribute :admin?, :boolean, allow_nil?: false, default: false
  end

  relationships do
    ...
  end

  postgres do
    table "users_organizations"
    ...
  end

  ...
end

defmodule UserOrganization do
  use Ash.Resource, data_layer: AshPostgres.DataLayer

  attributes do
    attribute :admin?, :boolean, allow_nil?: false, default: false
  end

  relationships do
    ...
  end

  postgres do
    table "users_organizations"
    ...
  end

  ...
end

What I want to do is to create a virtual attribute in the Organization resource that will tell if that user (the actor) is an admin. My first approach was to add this new relationship to the resource:

    has_many :users_organizations, UserOrganization

    has_many :users_organizations, UserOrganization

So I can get access to the UserOrganization resource directly from Organization. After that, I tried creating a calculation that would join that relationship and "extract" the admin? field:

  calculations do
    calculate :admin?, :boolean, expr(users_organizations.admin?)
  end

  calculations do
    calculate :admin?, :boolean, expr(users_organizations.admin?)
  end

That don't work, and I'm not sure how exactly I would filter that calculation to only get the user_organization from the actor. My second approach was to try an aggregate:

  aggregates do
    first :admin?, :users_organizations, :admin? do

      filter expr(user_id == ^actor(:id))
    end
  end

  aggregates do
    first :admin?, :users_organizations, :admin? do

      filter expr(user_id == ^actor(:id))
    end
  end

This also doesn't work, and aggregates also will generate a more complex query instead of simply doing the join by organization_id and user_id. Any suggestion on how I can acchieve that?

16 Replies

ZachDaniel•2y ago

🤔 I can add an option for this we already have the concept of doing simple joins for first aggregates that go over only to_one relationships so all we really need to do is expose that as an option for cases where we can't tell

BlibsOP•2y ago

That would be great! Right now my workaround is to have:

has_many :organizations, UserOrganization

has_many :organizations, UserOrganization

instead of

    many_to_many :organizations, Organization do
      through UserOrganization

      source_attribute_on_join_resource :user_id
      destination_attribute_on_join_resource :organization_id
    end

    many_to_many :organizations, Organization do
      through UserOrganization

      source_attribute_on_join_resource :user_id
      destination_attribute_on_join_resource :organization_id
    end

and do

  preparations do
    prepare build(load: [schools: [:school], organizations: [:organization]])
  end

  preparations do
    prepare build(load: [schools: [:school], organizations: [:organization]])
  end

instead of

  preparations do
    prepare build(load: [:schools, :organizations])
  end

  preparations do
    prepare build(load: [:schools, :organizations])
  end

Having that would allow me to make things simpler IMO

ZachDaniel•2y ago

oh, actually nevermind, I just realized you are looking for this to be scoped to the actor calculate :admin?, :boolean, expr(exists(user_organizations, user_id == ^actor(:id) and admin? == true)) thats what you want I think

BlibsOP•2y ago

Not sure, if I try to load that calculation with:

Accounts.load!(org, [:admin?], actor: user)

Accounts.load!(org, [:admin?], actor: user)

I get:

 
** (ArgumentError) `nil` is not a Spark DSL module.

    nil.spark_dsl_config()
    (spark 1.1.15) lib/spark/dsl/extension.ex:134: Spark.Dsl.Extension.dsl!/1
    (spark 1.1.15) lib/spark/dsl/extension.ex:163: Spark.Dsl.Extension.get_persisted/3
    (ash 2.9.27) lib/ash/filter/filter.ex:3033: Ash.Filter.do_hydrate_refs/2
    (ash 2.9.27) lib/ash/resource/calculation/expression.ex:131: Ash.Resource.Calculation.Expression.select/3
    (ash 2.9.27) lib/ash/query/query.ex:1082: Ash.Query.select_and_load_calc/3
    (ash 2.9.27) lib/ash/query/query.ex:1042: Ash.Query.load_resource_calculation/4
    (elixir 1.14.4) lib/enum.ex:2468: Enum."-reduce/3-lists^foldl/2-0-"/3
    (ash 2.9.27) lib/ash/api/api.ex:1708: Ash.Api.load/4
    (ash 2.9.27) lib/ash/api/api.ex:1665: Ash.Api.load!/4
    iex:8: (file)

 
** (ArgumentError) `nil` is not a Spark DSL module.

    nil.spark_dsl_config()
    (spark 1.1.15) lib/spark/dsl/extension.ex:134: Spark.Dsl.Extension.dsl!/1
    (spark 1.1.15) lib/spark/dsl/extension.ex:163: Spark.Dsl.Extension.get_persisted/3
    (ash 2.9.27) lib/ash/filter/filter.ex:3033: Ash.Filter.do_hydrate_refs/2
    (ash 2.9.27) lib/ash/resource/calculation/expression.ex:131: Ash.Resource.Calculation.Expression.select/3
    (ash 2.9.27) lib/ash/query/query.ex:1082: Ash.Query.select_and_load_calc/3
    (ash 2.9.27) lib/ash/query/query.ex:1042: Ash.Query.load_resource_calculation/4
    (elixir 1.14.4) lib/enum.ex:2468: Enum."-reduce/3-lists^foldl/2-0-"/3
    (ash 2.9.27) lib/ash/api/api.ex:1708: Ash.Api.load/4
    (ash 2.9.27) lib/ash/api/api.ex:1665: Ash.Api.load!/4
    iex:8: (file)

ZachDaniel•2y ago

oh, sorry

BlibsOP•2y ago

Either way, I think I would not be able to use it anyway since I want to load it when I get my user, meanign that I don't have an actor yet

ZachDaniel•2y ago

do you have a user_organizations relationship?

BlibsOP•2y ago

Yep

ZachDaniel•2y ago

    many_to_many :organizations, Organization do
      through UserOrganization
      join_relationship :user_organizations

      source_attribute_on_join_resource :user_id
      destination_attribute_on_join_resource :organization_id
    end

    many_to_many :organizations, Organization do
      through UserOrganization
      join_relationship :user_organizations

      source_attribute_on_join_resource :user_id
      destination_attribute_on_join_resource :organization_id
    end

add that join_relationship

BlibsOP•2y ago

defmodule Accounts.UserOrganization do
  @moduledoc false

  use Ash.Resource,
    data_layer: AshPostgres.DataLayer

  attributes do
    attribute :admin?, :boolean, allow_nil?: false, default: false
  end

  relationships do
    alias Accounts.{User, Organization}

    belongs_to :user, User do
      primary_key? true
      allow_nil? false
      attribute_writable? true
    end

    belongs_to :organization, Organization do
      primary_key? true
      allow_nil? false
      attribute_writable? true
    end
  end

  postgres do
    table "users_organizations"

    references do
      reference :user, on_update: :update, on_delete: :delete
      reference :organization, on_update: :update, on_delete: :delete
    end

    custom_indexes do
      index ["\"admin?\""], name: "users_organizations_admin_index"
    end

    repo Repo
  end
end

defmodule Accounts.UserOrganization do
  @moduledoc false

  use Ash.Resource,
    data_layer: AshPostgres.DataLayer

  attributes do
    attribute :admin?, :boolean, allow_nil?: false, default: false
  end

  relationships do
    alias Accounts.{User, Organization}

    belongs_to :user, User do
      primary_key? true
      allow_nil? false
      attribute_writable? true
    end

    belongs_to :organization, Organization do
      primary_key? true
      allow_nil? false
      attribute_writable? true
    end
  end

  postgres do
    table "users_organizations"

    references do
      reference :user, on_update: :update, on_delete: :delete
      reference :organization, on_update: :update, on_delete: :delete
    end

    custom_indexes do
      index ["\"admin?\""], name: "users_organizations_admin_index"
    end

    repo Repo
  end
end

ZachDaniel•2y ago

I was referring to a relationship you don't have in my example which was the cause of the error. Add the join_relationship option I mentioned above You don't have an actor yet, but you do have the user's id right? or not yet?

BlibsOP•2y ago

Yep, I want to do that when ash_authenticate fetches the user So I actually have the user email/pwd haha The calculation worked after I added the join_relationship btw.

ZachDaniel•2y ago

Can you move this to be on the user instead?

aggregates do
  list :admin_of, :organizations, :organization_id do
    filter expr(admin? == true)
  end
end

aggregates do
  list :admin_of, :organizations, :organization_id do
    filter expr(admin? == true)
  end
end

You could put that on the user to see what organizations they are an admin of

BlibsOP•2y ago

I could, but that means that when I wan´t to check for that information, I need to check in two places. Let's say I'm creating a page where I show a list of the user organizations, I would need to check, for each organization, if it is also inside the admin_of list in the user Btw, I think I found a but, not sure. If I remove the admin? == true from the calculation, it works. If I add that back, I get this error:

** (Ash.Error.Unknown) Unknown Error

* ** (ArgumentError) parameters must be of length 1 for query %Postgrex.Query{ref: #Reference<0.1342909402.405012485.110668>, name: "ecto_19973", statement: "SELECT o0.\"id\", o0.\"name\", o0.\"b2b?\", o0.\"inserted_at\", o0.\"updated_at\", exists((SELECT 1 AS \"result\" FROM \"public\".\"users_organizations\" AS su0 WHERE (su0.\"user_id\"::uuid = $1::uuid) AND (o0.\"id\" = su0.\"organization_id\")))::boolean FROM \"organizations\" AS o0", param_oids: [2950], param_formats: [:binary], param_types: [Postgrex.Extensions.UUID], columns: ["id", "name", "b2b?", "inserted_at", "updated_at", "exists"], result_oids: [2950, 1043, 16, 1114, 1114, 16], result_formats: [:binary, :binary, :binary, :binary, :binary, :binary], result_types: [Postgrex.Extensions.UUID, Postgrex.Extensions.Raw, Postgrex.Extensions.Bool, Postgrex.Extensions.Timestamp, Postgrex.Extensions.Timestamp, Postgrex.Extensions.Bool], types: {FeedbackCupcake.PostgresTypes, #Reference<0.1342909402.405143553.66672>}, cache: :reference}
  (postgrex 0.17.1) lib/postgrex/query.ex:80: DBConnection.Query.Postgrex.Query.encode/3
  (db_connection 2.5.0) lib/db_connection.ex:1336: DBConnection.maybe_encode/4
  (db_connection 2.5.0) lib/db_connection.ex:707: DBConnection.execute/4
  (ecto_sql 3.10.1) lib/ecto/adapters/postgres/connection.ex:102: Ecto.Adapters.Postgres.Connection.execute/4
  (ecto_sql 3.10.1) lib/ecto/adapters/sql.ex:858: Ecto.Adapters.SQL.execute!/5
  (ecto_sql 3.10.1) lib/ecto/adapters/sql.ex:828: Ecto.Adapters.SQL.execute/6
  (ecto 3.10.2) lib/ecto/repo/queryable.ex:229: Ecto.Repo.Queryable.execute/4
  (ecto 3.10.2) lib/ecto/repo/queryable.ex:19: Ecto.Repo.Queryable.all/3

** (Ash.Error.Unknown) Unknown Error

* ** (ArgumentError) parameters must be of length 1 for query %Postgrex.Query{ref: #Reference<0.1342909402.405012485.110668>, name: "ecto_19973", statement: "SELECT o0.\"id\", o0.\"name\", o0.\"b2b?\", o0.\"inserted_at\", o0.\"updated_at\", exists((SELECT 1 AS \"result\" FROM \"public\".\"users_organizations\" AS su0 WHERE (su0.\"user_id\"::uuid = $1::uuid) AND (o0.\"id\" = su0.\"organization_id\")))::boolean FROM \"organizations\" AS o0", param_oids: [2950], param_formats: [:binary], param_types: [Postgrex.Extensions.UUID], columns: ["id", "name", "b2b?", "inserted_at", "updated_at", "exists"], result_oids: [2950, 1043, 16, 1114, 1114, 16], result_formats: [:binary, :binary, :binary, :binary, :binary, :binary], result_types: [Postgrex.Extensions.UUID, Postgrex.Extensions.Raw, Postgrex.Extensions.Bool, Postgrex.Extensions.Timestamp, Postgrex.Extensions.Timestamp, Postgrex.Extensions.Bool], types: {FeedbackCupcake.PostgresTypes, #Reference<0.1342909402.405143553.66672>}, cache: :reference}
  (postgrex 0.17.1) lib/postgrex/query.ex:80: DBConnection.Query.Postgrex.Query.encode/3
  (db_connection 2.5.0) lib/db_connection.ex:1336: DBConnection.maybe_encode/4
  (db_connection 2.5.0) lib/db_connection.ex:707: DBConnection.execute/4
  (ecto_sql 3.10.1) lib/ecto/adapters/postgres/connection.ex:102: Ecto.Adapters.Postgres.Connection.execute/4
  (ecto_sql 3.10.1) lib/ecto/adapters/sql.ex:858: Ecto.Adapters.SQL.execute!/5
  (ecto_sql 3.10.1) lib/ecto/adapters/sql.ex:828: Ecto.Adapters.SQL.execute/6
  (ecto 3.10.2) lib/ecto/repo/queryable.ex:229: Ecto.Repo.Queryable.execute/4
  (ecto 3.10.2) lib/ecto/repo/queryable.ex:19: Ecto.Repo.Queryable.all/3

  (ash_postgres 1.3.30) lib/data_layer.ex:628: AshPostgres.DataLayer.run_query/2
  (ash 2.9.27) lib/ash/actions/read.ex:2618: Ash.Actions.Read.run_query/6
  (ash 2.9.27) lib/ash/actions/read.ex:1339: anonymous fn/4 in Ash.Actions.Read.data_field/3
  (ash 2.9.27) lib/ash/engine/engine.ex:537: anonymous fn/2 in Ash.Engine.run_iteration/1
  (ash 2.9.27) lib/ash/engine/engine.ex:558: anonymous fn/4 in Ash.Engine.async/2
  (elixir 1.14.4) lib/task/supervised.ex:89: Task.Supervised.invoke_mfa/2
  (elixir 1.14.4) lib/task/supervised.ex:34: Task.Supervised.reply/4
  (stdlib 4.3) proc_lib.erl:240: :proc_lib.init_p_do_apply/3
    (ash 2.9.27) lib/ash/error/error.ex:461: Ash.Error.choose_error/2
    (ash 2.9.27) lib/ash/error/error.ex:218: Ash.Error.to_error_class/2
    (ash 2.9.27) lib/ash/actions/read.ex:184: Ash.Actions.Read.do_run/3
    (ash 2.9.27) lib/ash/actions/read.ex:96: Ash.Actions.Read.run/3
    (ash 2.9.27) lib/ash/api/api.ex:1802: Ash.Api.read!/3
    iex:17: (file)

  (ash_postgres 1.3.30) lib/data_layer.ex:628: AshPostgres.DataLayer.run_query/2
  (ash 2.9.27) lib/ash/actions/read.ex:2618: Ash.Actions.Read.run_query/6
  (ash 2.9.27) lib/ash/actions/read.ex:1339: anonymous fn/4 in Ash.Actions.Read.data_field/3
  (ash 2.9.27) lib/ash/engine/engine.ex:537: anonymous fn/2 in Ash.Engine.run_iteration/1
  (ash 2.9.27) lib/ash/engine/engine.ex:558: anonymous fn/4 in Ash.Engine.async/2
  (elixir 1.14.4) lib/task/supervised.ex:89: Task.Supervised.invoke_mfa/2
  (elixir 1.14.4) lib/task/supervised.ex:34: Task.Supervised.reply/4
  (stdlib 4.3) proc_lib.erl:240: :proc_lib.init_p_do_apply/3
    (ash 2.9.27) lib/ash/error/error.ex:461: Ash.Error.choose_error/2
    (ash 2.9.27) lib/ash/error/error.ex:218: Ash.Error.to_error_class/2
    (ash 2.9.27) lib/ash/actions/read.ex:184: Ash.Actions.Read.do_run/3
    (ash 2.9.27) lib/ash/actions/read.ex:96: Ash.Actions.Read.run/3
    (ash 2.9.27) lib/ash/api/api.ex:1802: Ash.Api.read!/3
    iex:17: (file)

ZachDaniel•2y ago

uh....woah alright, well, I'll have to look at that tomorrrow Your best bet is probably to do one action to fetch the user w/o loading any data, and then use Api.load on that user to fetch all of the related things you want, with that user as the actor It would only really add a few ms to the request, and then you can use policies and stuff to enforce what that user can/can't access

BlibsOP•2y ago

Got it, makes sense, I will try that and see how it goes

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How to have a "virtual field" in a resource based from another resource?

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