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Piotr Solnica

@solnic

oh and typically you want to put error messages in a yaml file

uhm, actually this is not an equivalent of your example, seems like we need a negation support there

Chris Richards

@cmrichards

I get the idea though

Piotr Solnica

@solnic

ok cool :)

Chris Richards

@cmrichards

is there a "valid?" method or is that done differently?

Piotr Solnica

@solnic

no, it’s stateless

so it’s schema = MySchema.new and schema.call(params)

it returns a result object back with a ton of information

Chris Richards

@cmrichards

And the result object is a hash?

Piotr Solnica

@solnic

it’s a validation result object, it responds to #messages which gives you compiled error messages as a hash with access to string error messages and the input for each error

{:barcode_only=>[["Can only enter data into barcode OR job/sample fields, not both"], "123"]}

sth like that

Chris Richards

@cmrichards

I see. So there will be more work needed for it to work with Rails form_for helpers?

I look forward to using it. For now I gotta go. Thanks.

This seems a bit like reform contracts?

the "reform" gem

Piotr Solnica

@solnic

reform will use it soon (or even already has support for it)

we collaborate with Nick a lot lately

Chris Richards

@cmrichards

excellent

Piotr Solnica

@solnic

btw the missing ingredient is this:

rule(:barcode_only) do
  rule(:barcode) ^ not(rule(:job_number) | rule(:sample_number))
end

notice not

I gotta add it, it’s gonna be useful in many places anyway

Chris Richards

@cmrichards

What's the ^?

Piotr Solnica

@solnic

xor

Chris Richards

@cmrichards

Piotr Solnica

@solnic

either side must be true to make it all true

Chris Richards

@cmrichards

I know my CS ;-)

Piotr Solnica

@solnic

Chris Richards

@cmrichards

Although I didn't know it was a ruby operator until now!

Piotr Solnica

@solnic

hah yeah, it’s a native operator in ruby

true ^ true => false

true ^ false => true

Chris Richards

@cmrichards

yeah I just tried that

Piotr Solnica

@solnic

cool :)

Piotr Solnica

@solnic

class BarcodeSchema < Dry::Validation::Schema::Form
  key(:barcode, &:filled?)
  key(:job_number, &:int?)
  key(:sample_number, &:int?)

  rule(:barcode_only) do
    rule(:barcode) ^ (rule(:job_number) | rule(:sample_number))
  end
end

@cmrichards so, that’s the most concise way of writing this ^^^…but, there are a couple of things I realized while writing this

it seems like we have two concerns here, first one being the validation schema for valid types, the second one being high level rules that should be applied to already validated input

and…you can’t do it in one go, it’s a two step process, I gotta come up with a solution for this

Chris Richards

@cmrichards

What's your solution?

Piotr Solnica

@solnic

dryrb/dry-validation@0955118 <= this /c @cmrichards

after this addition your example can be written like that:

class BarcodeSchema < Dry::Validation::Schema::Form
  key(:barcode) do |barcode|
    barcode.none? | barcode.filled?
  end

  key(:job_number) do |job_number|
    job_number.none? | job_number.int?
  end

  key(:sample_number) do |sample_number|
    sample_number.none? | sample_number.int?
  end

  rule(:barcode_only) do
    rule(:barcode).filled? ^ (rule(:job_number).int? | rule(:sample_number).int?)
  end
end

notice that now you can compose higher level rules using specific predicates

Chris Richards

@cmrichards

Yes, it looks better now

Piotr Solnica

@solnic

this pretty much means we can easily specify validations that are strictly about type-safety and a separate set of higher level rules that rely on existing validation results

Chris Richards

@cmrichards

Shouldn't the last | be a & ?

Piotr Solnica

@solnic

no, because from what I remember you wanted to check if barcode is present only if both job number and sample number are empty

you could express it like that too: rule(:barcode).filled? & (rule(:job_number).none? & rule(:sample_number).none?)

I just wanted to use the new fancy xor :joy:

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