Using custom generators

[Andreas Liljeqvist]

Hi.

I can use the following link for generating a BigDecimal.

https://github.com/plumatic/schema/issues/324

How can I provide a custom generator for :a ?

{:a BigDecimal

 :b BigDecimal}

(there might be a lot more than two keys)

Thanks for any help.

[Jason Wolfe]

Once you add the BigDecimal generator, it should automatically work to
generate from the composite schema you provide. Or do you mean
something else? If so, can you please provide a concrete example of
the schema and what you want to generate from it?

Thanks,
Jason

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[Andreas Liljeqvist]

(def data {:a BigDecimal

                :b BigDecimal}

(c/complete {} data {} {BigDecimal (clojure.test.check.generators/fmap #(BigDecimal. (str %)) clojure.test.check.generators/double) })

If we apply a leaf-generator for BigDecimal, then all BigDecimals will use that.

I want to use custom generators for specific BigDecimal keys.

For example :a should always be negative and :b should always be positive.

This is a case of where we might use different types, but the constraints is only for generating a demo.

The types are actually BigDecimal, but some generated results are a bit improbable.

Does that make sense?

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[Jason Wolfe]

That makes sense, thanks.

To do this as-is, you will either have to provide a leaf generator for
`data` that generates the whole thing in one shot, or use a wrapper
(e.g. `(generators/fmap (fn [d] (update-in d :a #(Math/abs %))))`) to
transform the values . You can find an example of this in the
generators test.

If it's possible, a better approach might be to make your schema more
semantic, like:

(def PositiveDecimal (s/constrained BigDecimal pos?))
(def NegativeDecimal (s/constrained BigDecimal neg?))

(def data {:a PositiveDecimal :b NegativeDecimal}).

Then you might not even need to use custom generators (if the
constraints work as intended), but if desired you can just hang custom
generators on PositiveDecimal and NegativeDecimal, etc. Does that
make sense?

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[Andreas Liljeqvist]

Hi.

Sorry for my late reply.

It does make a lot of sense.

Thank you for your help.

--

Mvh

Andreas Liljeqvist

Systemutvecklare

ALDB Concrete Solutions AB