I need to verify my objects don't contain any undefined keys. Seems like a trivial feature. Is it not supported?

this is no issue but i wad wondering if you was gonna upload a updated verison for instaslayer desktop app

EzValidator is fantastic! I was wondering if there are plans to expand support to desktop platforms and what such an endeavor might entail?

When I pass a validator to a TextField and the validator is not required, it still returns an error when the value is null or empty.

I had to wrap the validators using this function

String? Function(String?) ifNotEmptyValidator(Function validator){
  return (String? value){
    if(value?.isEmpty ?? true){
      return null;
    }else{
      return validator(value);
    }
  };
}

...

ifNotEmptyValidator(EzValidator().phone("Incorrect Format").build())
ifNotEmptyValidator(EzValidator().url("Incorrect Format").build())

Then I checked Your Implementation and I found that Optional defaults to false, this is the main issue. Since you only have required function in the builder and not notRequired, then the default value for optional should be true, and should be changed to false when required is called, or you don't even need optional, if you always assume it's true unless required validation is added and call it first before all other validations.

class EzValidator {

  EzValidator();
  bool optional = true;
...
...

EzValidator required([String? message]) {
    optional = false;
    return _add((v) => v == null || v.trim().isEmpty
          ? message ?? globalLocale.required()
          : null);
  };
...
}

Or

without optional, the existence of requiredValidation is an indicator of whether it's optional or not.

class EzValidator {

  final List<StringValidationCallback> validations = [];
  StringValidationCallback? requiredValidation;

...
...
...

  String? _test(String? value) {
    
     if ( (requiredValidation ==null) && (value == null || value.isEmpty)) {
        return null;
      }
    for (var validate in [requiredValidation, ...validations]) {
 
      final result = validate(value);
      if (result != null) {
        return result;
      }
    }
    return null;
  }

...
...

EzValidator required([String? message]) {
    requiredValidation = ((v) => v == null || v.trim().isEmpty
          ? message ?? globalLocale.required()
          : null);
    return this;
  };
...
}

Or

Allow all validators to process nullable values and change _add to insert required validation at index 0, so the required validator will be called first.

Are there any validator types to validate this sort of object structure for ezvalidator?

{
  "fields": [
    {
      "name": "carlo",
      "age": 2,
    }
  ]
}