:one_of constraint for type string
There exists :one_of constraint for type :atoms on the resources, but this does not exist for type :string. Is there another way to restrict values to one of a list of strings?
11 Replies
There are a few other ways, yes 🙂
You can add a validation like so:
Thanks! With constraints I'm able to access the list (say for Option generation for select component) with
Ash.Resource.Info.attribute(resource, :options).constraints[:one_of]
To do the same thing I guess I need to write a function which pulls it from Ash.Resource.Info.validations?hmm...yeah that's probably the only way at the moment
what do you use that info for, out of curiosity?
We could potentially add support for
one_of on all typesMainly for forms and building values of selects. For the form on the UI I can grab the list to generate the options and keep those two in sync
That would be great! Because from my understanding doing operations with changesets (Changeset.change_attributes), the constraints correctly limit it, but with validations it only kicks in once acted upon?
You’ll get errors for all of them on validation
I’ll have to think about it because there are some implementation considerations.
Errors with constraints:
Valid with validations
yeah, but when you run the changeset action it will give you the errors, which is what happens on
AshPhoenix.Form.validate/2 for example
what I would suggest: write a custom type called YourApp.StringEnum that has a one_of constraint 😄I'm gonna have a lot of them 😅 . As far as implementation, I just copied atom implementation over which works. If there are larger architecture decisions that I'd understand I'd be happy to make a PR with those too
That looks right to me 🙂 I'm not convinced that we necessarily want to add the constraint to all types yet, so for now I think the custom type is the right answer. I'll let the idea percolate though