Ash Elixir•3y ago

Aggregate first the full resource instead of some field

I have a property resource that can contain offers. When I'm fetching the property, I want to also fetch the current offer from the actor if there is one. Right now, I have this:

  preparations do
    prepare build(load: :offeror_current_offer)
  end

  aggregates do
    first :offeror_current_offer, :offers do
      filter expr(offeror_id == ^actor(:id) and status in [:open, :accepted, :evaluating])

      sort updated_at: :desc
    end
  end

  preparations do
    prepare build(load: :offeror_current_offer)
  end

  aggregates do
    first :offeror_current_offer, :offers do
      filter expr(offeror_id == ^actor(:id) and status in [:open, :accepted, :evaluating])

      sort updated_at: :desc
    end
  end

But this will not work since the first aggregation requires me to select a field from :offers, but I want it to actually select the whole offer. Is there some way for me to do this with aggregates?

21 Replies

ZachDaniel•3y ago

has_one :offeror_current_offer, Offer do
  sort updated_at: :desc
end

has_one :offeror_current_offer, Offer do
  sort updated_at: :desc
end

no need for an aggregate there

BlibsOP•3y ago

Ah, that's cool! So, I added this:

    has_one :offeror_current_offer, Markets.Property.Offer do
      filter expr(offeror_id == ^actor(:id) and status in [:open, :accepted, :evaluating])

      sort updated_at: :desc
    end

    has_one :offeror_current_offer, Markets.Property.Offer do
      filter expr(offeror_id == ^actor(:id) and status in [:open, :accepted, :evaluating])

      sort updated_at: :desc
    end

BlibsOP•3y ago

But the whole thing exploded during query compilation 😅 Seems to be related to the ^actor(:id) bit

message.txt

ZachDaniel•3y ago

oh yeah sorry you can't use the actor in either filter You're going to want a calculation for this (sorry about that)

calculate :offeror_current_offer, GetCurrentOfferor

defmodule ...GetCurrentOfferror do
  use Ash.Resource.Calculation

  def calculate(records, _, %{actor: actor}) do
    Enum.map(records, fn record -> 
      ...get the current offer
    end)
  end
end

calculate :offeror_current_offer, GetCurrentOfferor

defmodule ...GetCurrentOfferror do
  use Ash.Resource.Calculation

  def calculate(records, _, %{actor: actor}) do
    Enum.map(records, fn record -> 
      ...get the current offer
    end)
  end
end

BlibsOP•3y ago

I think calculate has arity 3 right? Seems like it expects the return type as the second argument, I tried adding the Offer object to it but seems like that is not correct, I will take a look at the docs Yeah.. I don't get it. I'm adding the calculation this way:

calculate :offeror_current_offer, Markets.Property.Offer, GetCurrentOfferor

calculate :offeror_current_offer, Markets.Property.Offer, GetCurrentOfferor

But I get this error

== Compilation error in file lib/marketplace/markets/property.ex ==
** (ArgumentError) value nil is invalid for type {:parameterized, Marketplace.Markets.Property.Offer.EctoType, []}, can't set default
    (ecto 3.9.4) lib/ecto/schema.ex:2221: Ecto.Schema.validate_default!/3
    (ecto 3.9.4) lib/ecto/schema.ex:1928: Ecto.Schema.__field__/4
    (stdlib 4.1.1) erl_eval.erl:744: :erl_eval.do_apply/7
    (stdlib 4.1.1) erl_eval.erl:136: :erl_eval.exprs/6
    (elixir 1.14.0) lib/enum.ex:2468: Enum."-reduce/3-lists^foldl/2-0-"/3
    (stdlib 4.1.1) erl_eval.erl:744: :erl_eval.do_apply/7
    (stdlib 4.1.1) erl_eval.erl:136: :erl_eval.exprs/6
    (stdlib 4.1.1) erl_eval.erl:987: :erl_eval.try_clauses/10

== Compilation error in file lib/marketplace/markets/property.ex ==
** (ArgumentError) value nil is invalid for type {:parameterized, Marketplace.Markets.Property.Offer.EctoType, []}, can't set default
    (ecto 3.9.4) lib/ecto/schema.ex:2221: Ecto.Schema.validate_default!/3
    (ecto 3.9.4) lib/ecto/schema.ex:1928: Ecto.Schema.__field__/4
    (stdlib 4.1.1) erl_eval.erl:744: :erl_eval.do_apply/7
    (stdlib 4.1.1) erl_eval.erl:136: :erl_eval.exprs/6
    (elixir 1.14.0) lib/enum.ex:2468: Enum."-reduce/3-lists^foldl/2-0-"/3
    (stdlib 4.1.1) erl_eval.erl:744: :erl_eval.do_apply/7
    (stdlib 4.1.1) erl_eval.erl:136: :erl_eval.exprs/6
    (stdlib 4.1.1) erl_eval.erl:987: :erl_eval.try_clauses/10

From what I saw from other examples that should be the correct way to add the return type as the resource

ZachDaniel•3y ago

Yeah, that looks right to me, not sure what is going on there... oh actually one sec ash main should work for you now

BlibsOP•3y ago

Hm, I got the same error

ZachDaniel•3y ago

hm... you sure you updated? I just pushed it a second ago

BlibsOP•3y ago

let me try again

ZachDaniel•3y ago

are you sure its the same exact error?

BlibsOP•3y ago

== Compilation error in file lib/marketplace/markets/property.ex ==
** (ArgumentError) value nil is invalid for type {:parameterized, Marketplace.Markets.Property.Offer.EctoType, []}, can't set default
    (ecto 3.9.4) lib/ecto/schema.ex:2221: Ecto.Schema.validate_default!/3
    (ecto 3.9.4) lib/ecto/schema.ex:1928: Ecto.Schema.__field__/4
    (stdlib 4.1.1) erl_eval.erl:744: :erl_eval.do_apply/7
    (stdlib 4.1.1) erl_eval.erl:136: :erl_eval.exprs/6
    (elixir 1.14.0) lib/enum.ex:2468: Enum."-reduce/3-lists^foldl/2-0-"/3
    (stdlib 4.1.1) erl_eval.erl:744: :erl_eval.do_apply/7
    (stdlib 4.1.1) erl_eval.erl:136: :erl_eval.exprs/6
    (stdlib 4.1.1) erl_eval.erl:987: :erl_eval.try_clauses/10

== Compilation error in file lib/marketplace/markets/property.ex ==
** (ArgumentError) value nil is invalid for type {:parameterized, Marketplace.Markets.Property.Offer.EctoType, []}, can't set default
    (ecto 3.9.4) lib/ecto/schema.ex:2221: Ecto.Schema.validate_default!/3
    (ecto 3.9.4) lib/ecto/schema.ex:1928: Ecto.Schema.__field__/4
    (stdlib 4.1.1) erl_eval.erl:744: :erl_eval.do_apply/7
    (stdlib 4.1.1) erl_eval.erl:136: :erl_eval.exprs/6
    (elixir 1.14.0) lib/enum.ex:2468: Enum."-reduce/3-lists^foldl/2-0-"/3
    (stdlib 4.1.1) erl_eval.erl:744: :erl_eval.do_apply/7
    (stdlib 4.1.1) erl_eval.erl:136: :erl_eval.exprs/6
    (stdlib 4.1.1) erl_eval.erl:987: :erl_eval.try_clauses/10

ZachDaniel•3y ago

how did you update to main? you set it to github: "ash-project/ash" ? did mix deps.update ash?

BlibsOP•3y ago

Yep

ZachDaniel•3y ago

🤔 Can you comment out your calculation and in iex do this actually nvm I see whats going on okay try main again

BlibsOP•3y ago

Yep! Now it is compiling 😁 So, should I expect the calculation to have the actor inside the context (last field of calculate function) by default if the action itself was called with the actor set? Because I'm not getting it

ZachDaniel•3y ago

😢 I keep leading you astray with this. The actor is not passed to calculations There is an open ticket for this to be fixed

BlibsOP•3y ago

So I guess for now there is no good way to calculate extra field in the resource that requires an actor?

ZachDaniel•3y ago

lemme try to fix it, one sec alright, try main the actor should be in the context now

BlibsOP•3y ago

Yep, now I can see the actor! Amazing work as always! So, last question (hopefully) about this. I see that Ash is smart when doing queries that need to fetch data from a lot of resources, it sends the resource's ids as a list and fetches data to all of them in a single query. I don't want to do one query per resource inside the calculate function, so can you direct me to some code, or where Ash does that single query so I can use as reference and do the same with my own query for this calculation?

ZachDaniel•3y ago

The calculation function takes a list of records and returns a list of results So that you can do exactly that same kind of thing i.e get the ids of all the records being loaded, and then fetch only the relevant records, and then return them properly i.e

def calculate(records, _, %{actor: actor}) do
  record_ids = Enum.map(records, &(&1.id))

  stuff = get_stuff(record_ids, actor)

  Enum.map(records, fn record -> 
    stuff[record.id]
  end)
end

def calculate(records, _, %{actor: actor}) do
  record_ids = Enum.map(records, &(&1.id))

  stuff = get_stuff(record_ids, actor)

  Enum.map(records, fn record -> 
    stuff[record.id]
  end)
end

BlibsOP•3y ago

All right! So here is my solution in case someone wants to use it as a reference: In my Offer resource, I created an action to retrieve offers from a list of properties_ids:

    read :list_own_valids_from_properties do
      argument :properties_ids, {:array, :uuid} do
        allow_nil? false
      end

      prepare build(sort: [updated_at: :desc])

      filter expr(
               property_id in ^arg(:properties_ids) and offeror_id == ^actor(:id) and
                 status != :old
             )
    end

    read :list_own_valids_from_properties do
      argument :properties_ids, {:array, :uuid} do
        allow_nil? false
      end

      prepare build(sort: [updated_at: :desc])

      filter expr(
               property_id in ^arg(:properties_ids) and offeror_id == ^actor(:id) and
                 status != :old
             )
    end

On my Property resource, I added this calculation:

  calculations do
    calculate :offeror_current_offer, Markets.Property.Offer, GetCurrentOfferor
  end

  calculations do
    calculate :offeror_current_offer, Markets.Property.Offer, GetCurrentOfferor
  end

And here is the calculation implementation:

defmodule GetCurrentOfferor do
  alias Marketplace.Markets.Property.Offer

  use Ash.Calculation

  @impl true
  def calculate(properties, _, %{actor: actor}) do
    properties_ids = Enum.map(properties, & &1.id)

    offers =
      %{properties_ids: properties_ids}
      |> Offer.list_own_valids_from_properties!(actor: actor)
      |> Enum.map(fn %{property_id: property_id} = offer -> {property_id, offer} end)
      |> Enum.into(%{})

    Enum.map(properties, fn %{id: property_id} ->
      offers[property_id]
    end)
  end
end

defmodule GetCurrentOfferor do
  alias Marketplace.Markets.Property.Offer

  use Ash.Calculation

  @impl true
  def calculate(properties, _, %{actor: actor}) do
    properties_ids = Enum.map(properties, & &1.id)

    offers =
      %{properties_ids: properties_ids}
      |> Offer.list_own_valids_from_properties!(actor: actor)
      |> Enum.map(fn %{property_id: property_id} = offer -> {property_id, offer} end)
      |> Enum.into(%{})

    Enum.map(properties, fn %{id: property_id} ->
      offers[property_id]
    end)
  end
end

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Aggregate first the full resource instead of some field

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