Filtering inside a load

Hopefully an easy one. I have a code interface that I'm calling inside a calculation module like this:

defp calculate_least_engaged(organization, after_datetime, before_datetime) do
  descendant_orgs = Organization.get_descendant_organizations!([organization.id], load: [users: [:first_name, :last_name]])
  ...
end

defp calculate_least_engaged(organization, after_datetime, before_datetime) do
  descendant_orgs = Organization.get_descendant_organizations!([organization.id], load: [users: [:first_name, :last_name]])
  ...
end

Assuming I pass a graduation_year argument to the calculation (and access it as the fourth param on the function), how can I filter the users that are being loaded?

8 Replies

barnabasj•6mo ago

You can also supply a inital query for the load

require Ash.Query

defp calculate_least_engaged(organization, after_datetime, before_datetime) do
  query =
    User
    |> Ash.Query.select([:first_name, :last_name])
    |> Ash.Query.filter(graduation_year == ^Ash.Changeset.get_argument(changeset, :graduation_year)


  descendant_orgs = Organization.get_descendant_organizations!([organization.id], load: [users: query])
  ...
end

require Ash.Query

defp calculate_least_engaged(organization, after_datetime, before_datetime) do
  query =
    User
    |> Ash.Query.select([:first_name, :last_name])
    |> Ash.Query.filter(graduation_year == ^Ash.Changeset.get_argument(changeset, :graduation_year)


  descendant_orgs = Organization.get_descendant_organizations!([organization.id], load: [users: query])
  ...
end

EgeOP•6mo ago

where is changeset coming from?

barnabasj•6mo ago

ah sorry, I mixed up changes and calculations it should be

require Ash.Query

defp calculate_least_engaged(organization, after_datetime, before_datetime) do
  query =
    User
    |> Ash.Query.select([:first_name, :last_name])
    |> Ash.Query.filter(graduation_year == ^context.arguments.graduation_year)


  descendant_orgs = Organization.get_descendant_organizations!([organization.id], load: [users: query])
  ...
end

require Ash.Query

defp calculate_least_engaged(organization, after_datetime, before_datetime) do
  query =
    User
    |> Ash.Query.select([:first_name, :last_name])
    |> Ash.Query.filter(graduation_year == ^context.arguments.graduation_year)


  descendant_orgs = Organization.get_descendant_organizations!([organization.id], load: [users: query])
  ...
end

context should be the 3. argument to the calculate function your are calling this private function from

Straffern•2mo ago

@barnabasj Is this some sort of annonymous calculation or is it a filter applied to the relationship users? If possible I want to apply a filter to loading of a relationship, inside the load callback for a calculation.

barnabasj•2mo ago

it passes an initial query that is than used to build the query for the relationship

Straffern•2mo ago

Any resource where I can read more about this? Or where do I find the implementation of this?

barnabasj•2mo ago

https://hexdocs.pm/ash/relationships.html#more-complex-data-loading it's mentioned in the guide here

Straffern•2mo ago

Neat! I totally missed this! Much appreciated 🙏

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Filtering inside a load

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