Ash Elixir•3y ago

Virtual attributes

I have several manual relationships that are populated using recursive queries, and I would like to be able to expose the depth and path fetched by those queries on the related resource. When not in the context of the relationship, these attributes don't make sense, and thus needn't be queried nor have columns in the table. Is there a way to create "placeholder" attributes that will be valid in the resource struct, for purposes of manual population? Right now, I'm putting them in __metadata__, which hopefully is safe.

6 Replies

ZachDaniel•3y ago

Metadata is the place for that kind of thing 🙂

\ ឵឵឵OP•3y ago

Thanks mate.

\ ឵឵឵OP•3y ago

Think this is related to https://discord.com/channels/711271361523351632/1019647368196534283/threads/1091304226040324117 from yesterday?

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\ ឵឵឵OP•3y ago

For the case of queried attributes, being able to specify something like:

relationships do
  many_to_many :teacher, App.Teacher do
    join_attributes [:role]
  end
end

relationships do
  many_to_many :teacher, App.Teacher do
    join_attributes [:role]
  end
end

Populating these in __metadata__ or another safe place purpose-built for this?

ZachDaniel•3y ago

Could you tell me a bit more about what you're doing?

\ ឵឵឵OP•3y ago

I think he was trying to have a role attribute on his many_to_many join resource teachers_courses, specifying whether that teacher was primary, secondary, etc. The topic overall was interesting because it's not uncommon to want to have data on graph edges. The way I've been handling this is to transform many_to_many into has_many with the join resource and use preparations if it's the case that I always care about the related resource and not just the edge metadata.

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Virtual attributes

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