spacebat
Read action by related struct
I have a belongs_to :definition relationship on a resource and can read all the resource instances belonging to a definition with:
read :by_definition_id do
argument :definition_id, :string
filter expr(definition_id == ^arg(:definition_id))
end
I figured it would be nice to have something like:
read :by_definition do
argument :definition, :map
filter expr(definition_id == ^arg(:definition)[:id])
end
However I can’t get this to compile, nor using .id or various other combinations. I just can’t seem to connect the definition argument’s id attribute to the filter expression.
Marked As Solved
spacebat
Thanks @barnabasJ that got me on the right track:
require Ash.Query
read :by_definition do
argument :definition, :map
prepare fn query, _context ->
definition_id = Ash.Query.get_argument(query, :definition).id
Ash.Query.filter(query, definition_id == ^definition_id)
end
end
Also Liked
barnabasJ
You might need to do it in a preparation to get to the value
read :by_definition do
argument :definition, :map
prepare fn query, _ ->
argument_definition_id = Ash.Query.get_argument(query, :definition)[:id]
query
|> Ash.Query.filter(definition_id == ^argument_definition_id)
end
end
Last Post!
zachdaniel
If this was something you wanted to be able to use throughout your application, you could define a custom type and a custom preparation and get pretty elegant usage:
read :by_definition do
# you can get custom short names with a configuration, so you can do this w/o anything built into ash
argument :thing, :struct_or_id, constraints: [for: TargetResource]
# you can import functions that return `{Module, opts}`, just like builtins
prepare filter_by_struct_or_id(:definition_id, :thing)
end
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