trim + empty confuses me

[awilkins]

Context

• node version: 6.9.1
• joi version: 9.2.0
• environment (node, browser): node
• used with (hapi, standalone, ...): just node in a REPL
• any other relevant information:

What are you trying to achieve or the steps to reproduce ?

Describe your issue here, include schemas and inputs you are validating if needed.

const schema = Joi.string().trim().empty('');
schema.validate(' '); 

Which result you had ?

"value" is not allowed to be empty

What did you expect ?

Successful validation.

trim() states in it's documentation that it edits the field. Intuitively I expected that edit to be applied before the next step in the schema, such that the .empty('') would receive an empty string since the input consisted only of whitespace.

The correct way to do this ... seems to be to pass /\s+/ to .empty()

const schema = Joi.string().empty(/\s+/).trim();
schema.validate(' '); // passes (and value is undefined)

Most of the documentation uses .empty('') though..

Would it break everyone's world if .trim() was applied before other validation.....? Possibly.

At a min. I'd like to see the docs improved to state that

• Conversions are applied after validations (or whatever the actual behaviour is)
• Maybe an example or 2 that uses that whitespace regex with .empty() in that context

[awilkins]

Hah, I do of course mean /^\s*$/ because the other one is wayyyyy to general

[awilkins]

But ...

const schema = Joi.string().empty(/^\s*$/);
schema.validate(''); // fails

Arrgh.

/^\s*$/.exec('') === 
[ '', index: 0, input: '' ]

The regex matches empty string. Why isn't it considered empty since empty has been told that anything that matches the regex is empty?

[Marsup]

Because your schema is strictly equivalent to Joi.string().empty(Joi.string().regex(/^\s*$/)), which will fail for the same reason a simple string would fail on an empty string. To make it work you'd need Joi.string().empty(Joi.string().allow('').regex(/^\s*$/)).

I'll check to see if the complexity of supporting this exceeds what I'm willing to support, will report back.

[awilkins]

Thanks for the workaround anyway 👍

[lock]

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