Catel.MVVM.ViewModelBase.OnValidatingFields C# (CSharp) Method

        protected override void OnValidatingFields(IValidationContext validationContext)
        {
            base.OnValidatingFields(validationContext);

            // Map all field errors and warnings from the model to this viewmodel
            foreach (var viewModelToModelMap in _viewModelToModelMap)
            {
                var mapping = viewModelToModelMap.Value;
                var model = GetValue(mapping.ModelProperty);
                string[] modelProperties = mapping.ValueProperties;

                foreach (var modelProperty in modelProperties)
                {
                    bool hasSetFieldError = false;
                    bool hasSetFieldWarning = false;

                    // IDataErrorInfo
                    var dataErrorInfo = model as IDataErrorInfo;
                    if (dataErrorInfo != null)
                    {
                        if (!string.IsNullOrEmpty(dataErrorInfo[modelProperty]))
                        {
                        validationContext.AddFieldValidationResult(FieldValidationResult.CreateError(mapping.ViewModelProperty, dataErrorInfo[modelProperty]));

                            hasSetFieldError = true;
                        }
                    }

                    // IDataWarningInfo
                    var dataWarningInfo = model as IDataWarningInfo;
                    if (dataWarningInfo != null)
                    {
                        if (!string.IsNullOrEmpty(dataWarningInfo[modelProperty]))
                        {
                        validationContext.AddFieldValidationResult(FieldValidationResult.CreateWarning(mapping.ViewModelProperty, dataWarningInfo[modelProperty]));

                            hasSetFieldWarning = true;
                        }
                    }

                    // INotifyDataErrorInfo & INotifyDataWarningInfo
                    if (_modelErrorInfo.ContainsKey(mapping.ModelProperty))
                    {
                        var modelErrorInfo = _modelErrorInfo[mapping.ModelProperty];

                        if (!hasSetFieldError)
                        {
                            foreach (string error in modelErrorInfo.GetErrors(modelProperty))
                            {
                                if (!string.IsNullOrEmpty(error))
                                {
                                validationContext.AddFieldValidationResult(FieldValidationResult.CreateError(mapping.ViewModelProperty, error));
                                    break;
                                }
                            }
                        }

                        if (!hasSetFieldWarning)
                        {
                            foreach (string warning in modelErrorInfo.GetWarnings(modelProperty))
                            {
                                if (!string.IsNullOrEmpty(warning))
                                {
                                validationContext.AddFieldValidationResult(FieldValidationResult.CreateWarning(mapping.ViewModelProperty, warning));
                                    break;
                                }
                            }
                        }
                    }
                }
            }
        }