Required properties with empty strings

[mdesousa]

Hi! I'm creating an AutoField and noticed that a user can delete a value for a required field, and no error is detected.
This is when using json-schema... the value is set to an empty string, which strictly speaking is a value but not the behavior that we want for a form.
Any suggestions on how to handle this easily and globally?
We are using meterial ui... thanks!

[radekmie]

Hi @mdesousa. The thing is, that an empty string is a valid string. It's up to you to decide what should the schema check for. I'd suggest one of the following, in the order of my personal preference:

1. Use pattern or format to specify the... Well, pattern or format of the string.
2. Use minLength: N to specify the minimum input length.
3. Create a custom keyword like isNotEmpty.

Please note that all of the above require changing your schema. That's not necessarily bad, as one, this can be (semi-)automated, and clearly defines your intention.

Also, remember that there's no trimming by default, and you may want to use a custom keyword for that as well. Luckily, ajv-keywords got you covered with its transform keyword.

[radekmie]

Yes, that's somehow problematic, I know. To be honest no, I don't see an easy solution here. One thing that I often saw in a couple of projects was a "clean" phase before validation, that'd remove empty strings and arrays, etc.

[Krypt0r7]

Hi @radekmie and @mdesousa!

This is exactly how we solved the issue. We had problems with some Objects and Lists that when first had a value that then where removed/deleted still was an empty List/Object. This was problematic due to server side validations and the need to keep some properties as null.

We used Lodash to work through the model to set all empty properties to null before submit to server.

And receiving a value that is null (lists, objects) makes the form not editable.

To me the expected behaviour should be to remove the property if it is empty (mostly Arrays) or at least set it to null.

[radekmie]

And receiving a value that is null (lists, objects) makes the form not editable.
[...] or at least set it to null.

But does your schema actually allow nulls in these values? The problem here is that we cannot allow nulls everywhere, because often it's against the schema. And simply removing the values is a valid approach, yet we haven't gone that way. We may consider that for the future (at least v4 as it's a breaking change).

[mdesousa]

hi @radekmie what is the best way to do a "clean" of a field before validation?

[radekmie]

@mdesousa you can use modelTransform for that, or do it directly in the validator.