Field type to validate "free" text inputs

[AndreFCruz]

I'm using the FreeTextFieldType class for an input that takes the following form:

• <input_name>=<sequence-of-numbers>
• e.g., arg1=1,0.3,9.8,2

I'm using the free text field as this is the only current suitable option, but I think it would be useful to add an optional parameter to the class constructor with a regex validator string, so we can check whether the input is valid before spinning-up a new model train process.

I think this minor modification to FreeTextFieldType could be useful to more people; and in my use case I'd just implement the input above as: new FreeTextFieldType("", "^((\d+(\.\d*)?,)*(\d+(\.\d*)?))?$") (1st parameter is the default value)

Shall I implement this and send in a PR?

PS: another option would be creating an entirely new FieldType CSVNumericFieldType that would be more specific to my case and would require larger code changes, but would also work.

[ghost]

It's an okay from me. Please remember to not introduce breaking change (e.g., overload the constructor instead of changing its signature)

[antssilva96]

I think that makes sense, the current validate method is doing nothing anyways :thinking:

Make sure that if no validation is provided the result is still a Optional.empty() to preserve current behavior.

If you need any help, let me know!