Add required_with, required_with_all, required_without, required_without_all validators

[mashmooli]

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• Tests exist or have been written that cover this particular change.

Change Details:
add these validators

• required_with: The field under validation must be present and not empty only if any of the other specified fields are not empty, (required_with:field1,field2);
• required_with_all: The field under validation must be present and not empty only if all of the other specified fields are not empty, (required_with_all:field1,field2);
• required_without: The field under validation must be present and not empty only when any of the other specified fields are empty, (required_without:field1,field2);
• required_without_all: The field under validation must be present and not empty only when all of the other specified fields are empty, (required_without_all:field1,field2).

@go-playground/admins

[coveralls]

Coverage remained the same at 100.0% when pulling 8c22169 on mashmooli:v9 into 46b4b1e on go-playground:v9.

[deankarn]

Hey @mashmooli thanks for the PR! nice work!

I have a couple of requests before I can merge:

• can you add some more test cases? it looks like the current ones don't test all of the new code paths yet.
• can you add these new methods to the docs here, I'm sure a ton of other people will find the new validations useful as well :)

[mashmooli]

Hi @deankarn thanks for the reply.
I added new methods to the docs and I'll be working on test cases soon.

[deankarn]

@mashmooli merged, I think that a cool addition would be allowing this to work with nested structures also :)

The helper functions exist within this repo if you're interested :)
eg. https://github.com/go-playground/validator/blob/v9/util.go#L60

[andig]

@mashmooli hope it is ok to be asking here. I had expected the following to throw an error but it isn't:

func TestModbusConfigFoo(t *testing.T) {
	type Settings struct {
		Opt, Val string
	}

	cc := struct {
		Model    string
		Value    string
		Settings *Settings `validate:"required_without_all=Model Value"`
	}{
		Model: "foo",
		// Value: "bar",
	}

	validate := validator.New()
	if err := validate.Struct(cc); err == nil {
		t.Error(err)
	}
}

Shouldn't that be covered by required_without_all?