Set default value if validation is failed. especially for query params which are optional

[pnutmath]

• node version - v12.22.1
• celebrate version - 15.0.0
• joi version (via npm ls --depth=0 | grep joi) - NA

The issue I am having with celebrate is:

Set default value if validation is failed. especially for query params which are optional. Can we support this?

[arb]

Joi has a .default() method available on every type. See this test for a code example.

[pnutmath]

Consider below scenario:

 page: Joi.object().keys({
    page: Joi.number().min(1).default(1),
    limit: Joi.number().min(1).default(10),
  }),

here, in case my request is like /?page=&limit=0

then page failed because it considered as string and limit failed because of min criteria.

As query params are optional, I am interested to set default value even after validation fails, without rejecting request. I don't think its happening right now

[arb]

It's rejecting because the schema says that limit minimum is 1, but it's being set to 0 so the request is invalid. celebrate doesn't apply the transformations unless the request passes validation.

If you make limit 2, then it should pass and page should default to 1.

[pnutmath]

Yes understood @arb, but I am saying like even though it fails validation for query params and if we have set default then validation should pass with default value.

I am suggesting this for query params only.

[AdamAld]

@pnutmath Your suggestion breaks standard validation for optional keys in the schema.. A possible workaround could be to use the .when(..) functionality on the schema itself to mutate the validation of that field (any().when(..) Docs), or using any of their Alternative helpers (alternatives.conditional|match|try(..) Docs).

Hope this helps!

[stale[bot]]

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