ash-project / ash-project/ash

Show an error if an argument defined in `define_calculation` is not accepted in the calculation itself

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enhancement
Dominant language
Elixir
Stars
2.5k
Forks
426
Avg merge
23h 26m
Merged PRs (30d)
46

Description

Is your feature request related to a problem? Please describe.
I just faced a bug where my define_calculation definition included an argument that wasn't listed in the calculation itself, i.e.

code_interface do
  define_calculation :display_product_variant, args: [:_record, :product_variant_id]
end

calculations do
    calculate :display_product_variant,
               :struct,
               Calculations.DisplayProductVariant,
               constraints: [instance_of: Shopifex.Products.ProductVariant]
end

and I didn't figure out why until @sevenseacat pointed it out.

Describe the solution you'd like
It'd be helpful if, in cases like these, an error was thrown saying that the calculation code interface is attempting to define an argument not accepted by the calculation.

Additional context
@zachdaniel on Discord:

I think whats "complicated" about it is that its using that as a ref
and we don't know what references a calculations use
i.e an attribute reference in an expression calculation 
but...your calculation doesn't define an expression, so we actually could have done that

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by tracing the define_calculation code interface and the calculations definition shown in the issue, then inspect how calculation arguments and references are validated. Determine whether the calculation can identify accepted arguments across the mentioned calculation forms, and treat completion as producing a clear error for an unsupported code-interface argument without breaking valid references.

Written by the indexing model from the issue text.

Assessment

Tech stack
elixir
Domain
backend, backend-api-design
Issue type
Feature
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
30/100

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