validationMessage for custom validators

[plong0]

I have created a custom form type, which adds a directive to the input. In the directive's link, I am adding a custom $validator to ngModel:

ngModel.$validators.foo = function(modelValue, viewValue){
  var value = modelValue || viewValue;
  return (value == 'bar');
};

(actual validator is more complex, so a simple tv4 pattern is not enough)

How can I set a custom message for this validation? I would have thought {validationMessage: {foo: "Foo is not bar!"}} would have done it... but the error message renders as [object Object]

[plong0]

Ok, found a solution that replaces the schemaError function with a customError function.
This solution preserves any schema-validation errors, and still allows the validationMessage to be set by the form json.

In the custom directive's link, I now have:

var error;
scope.customError = function(){
  return scope.schemaError() || error;
};

ngModel.$validators.foo = function(modelValue, viewValue){
  var value = modelValue || viewValue;
  if(value != 'bar'){
    error = { code: 'foo', message: 'Foo is not bar!' };
    return false;
  }
  delete error;
  return true;
};

In the .run(['$templateCache', function($templateCache){ ... }]) (or wherever you define your template), I replace schemaError() with customError():

var tmpl = $templateCache.get('directives/decorators/bootstrap/default.html');
var tmplCustom = tmpl.replace('type="{{form.type}}"', 'type="text" custom-directive'); // apply the custom directive
tmplCustom = tmplCustom.replace(/schemaError/g, 'customError'); // use custom errors

$templateCache.put(
  'custom-form-type.html',
  tmplCustom
);

And of course in the .config(['schemaFormDecoratorsProvider', function(schemaFormDecoratorsProvider){ ... }]) we set up the custom form type:

schemaFormDecoratorsProvider.addMapping(
  'bootstrapDecorator',
  'custom-form-type',
  'custom-form-type.html'
);

[plong0]

I wonder if a more elegant solution is for the sfArray directive (which provides the scope.schemaError() function) to expose scope.error rather than a local var error?