Format constraint runs on empty values

[itamargiv]

Description

In case I need to validate the format of a non required attribute someAttribue, running the validate on this attribute when it is empty '' or ' ' will still return the validation failure message.

Desired use case

To skip the Regex comparison when an attribute is empty. This seems to be the inverse of #99 and indeed, this behavior was introduced in 0.11.0

Is there a way to mitigate between those two opposing use cases? Is there a workaround here that I am missing?

In any case, will revert to version 0.10.0 for now :)

[itamargiv]

#182 Seems to be related as well

P.S. Will be happy to create a PR if you point me in the right direction. I didn't get to dig into the code just yet.

[jakee]

@itamargiv I have solved this problem by wrapping my format constraints in a function that returns false if the value is an empty string. You can read more about constraints as function here.

function optionalConstraint (options) {
  return function(value) {
    if (validate.isEmpty(value)) return false; // don't validate empty values
    return options; // use the provided constraint options otherwise
  }
}

This function can then be used to wrap your constraints like this:

  url: {
    length: {
      maximum: DEFAULT_FIELD_MAX_LENGTH
    },
    format: optionalConstraint({
      pattern: validURL,
      message: 'must be a valid URL'
    })
  }

The solution is very lightweight so at least I'm using it gladly over downgrading versions.

[itamargiv]

@jakee Thank you for the workaround, looks great. I'll try to implement and update you if it worked for my usecase. I agree, a lightweight workaround is always much better than rolling back.

[ansman]

From now on empty strings, arrays etc are treated as values.

You can use attributes.myAttribute = validate.sanitizeFormValue(attributes.myAttribute) (it's not documented but it will probably be made public)