How to sort by a value from a joined resource?

The most straightforward way is to use a calculation and sort on the calculation.

calculate :score, :decimal, expr(b.score)

and now you can sort by score

How would one make this work with Ash.Filter.parse_input and Ash.Sort.parse_input?

Adding the calculation to my “Site” to export customer.name:

  calculations do
    calculate :customer_name, :ci_string, expr(customer.name)
  end

Allows me to get at the value in query results (and sort on it):

        sites =
          Site
          |> Ash.Query.load([:customer_name])
          |> Ash.read!()

However, trying to allow the user to sort/filter on this column is less successful:

{:ok, sorts} = Ash.Sort.parse_input(Site, ["customer_name"])

Yields…

[error] ** (MatchError) no match of right hand side value: {:error, %Ash.Error.Query.NoSuchField{resource: MyApp.Sites.Site, field: "customer_name", splode: nil, bread_crumbs: [], vars: [], path: [], stacktrace: #Splode.Stacktrace<>, class: :invalid}}

The nutshell is I’m trying to put my “Sites” in a table with clickable/sortable column headers that are also representated in the query string.

Disregard. I forgot to mark the calculation value as public. parse_input is totally doing it’s job! Sorry.

For anyone else who makes the same mistake. Calculation should have been:

  calculations do
    calculate :customer_name, :ci_string, expr(customer.name), public?: true
  end

The calculation must be made public to be exposed to parse_input/2

  calculations do
    calculate :customer_name, :ci_string, expr(customer.name), public?: true
  end

For more complex cases, like if there is no corresponding calculation or you don’t want to make the calculation public, you can use the 3rd handler argument to sort_input.

For example:

require Ash.Sort
...

{:ok, sorts} = Ash.Sort.parse_input(Site, ["customer_name"], fn "customer_name" -> 
  Ash.Sort.expr_sort(customer.name)
end)

Didn’t see your message before I posted

So sorry about that! I appreciate the response and the note on additional handler. That’ll come in handy. Thank you!