Custom string validator function adds unwanted key to parent object

[rmattos500]

Adding a custom string validator function seems to have caused my other validation to stop working correctly.

I have simplified my code down and attached a link to the repo containing an example of the issue I am running into. In the example, I am using a dummy custom string validator function that should not be causing the validation to fail, however when run, the validation fails due to some of my other rules I defined in my schema. If you comment out the custom string validator function, the rest of the rules that previously failed now pass. Thus why I believe the issue seems to stem from defining a custom string validator function.

Link to example repo:
https://github.com/rmattos500/fastest-validator-issue

[erfanium]

Confirmed, for now you can just use strict: "remove" to bypass this bug,

[erfanium]

repro

commenting out custom checker function will change the final result

const v = new Validator({
	// debug: true,
	useNewCustomCheckerFunction: true,
	defaults: {
		object: {
			strict: true,
		},
		string: {
			custom(value) {
				return value;
			},
		},
	},
});

const schema = {
	method: { type: "equal", value: "bar" },
	extra: "string",
};

const check = v.compile(schema);

const obj = {};
const res = check(obj);

console.log(obj);

[erfanium]

@icebob I think we should never call custom checker function when value is null or undefined

related to #189

[rmattos500]

@erfanium Thanks for looking into this so quickly and for the suggested bypass!

[icebob]

The issue related to defaults?

[erfanium]

@icebob Nah, Run my repro code to better understand it

[icebob]

Simpler repro:

const v = new Validator({
	// debug: true,
	useNewCustomCheckerFunction: true,
});

const schema = {
	extra: { type: "string", custom: value => value }
};

const check = v.compile(schema);

const obj = {};
const res = check(obj);

console.log(obj);

So the issue is that FV populates the original object with extra: undefined?

Can we move this highlighted parts into the "else" branch?

[icebob]

@erfanium ?

[erfanium]

Can we move this highlighted parts into the "else" branch?

I'm okay with this solution. (In fact, my solution was the same, but in another words)