Merge pull request #2662 from mrhmouse/better-error-message-when-more…

…-than-one-fluent-validator-exists Use a better error message when picking a fluent validator is ambiguous
NancyFx · Dec 29, 2016 · c91bfc6 · c91bfc6
2 parents 692196b + 5ae6d59
commit c91bfc6
Showing 1 changed file with 16 additions and 2 deletions.
diff --git a/src/Nancy.Validation.FluentValidation/FluentValidationValidatorFactory.cs b/src/Nancy.Validation.FluentValidation/FluentValidationValidatorFactory.cs
@@ -45,9 +45,23 @@ private IValidator GetValidatorInstance(Type type)
         {
             var fullType =
                 CreateValidatorType(type);
+            var available = this.validators
+                .Where(validator => fullType.GetTypeInfo().IsAssignableFrom(validator.GetType()))
+                .ToArray();
 
-            return this.validators
-                .SingleOrDefault(validator => fullType.GetTypeInfo().IsAssignableFrom(validator.GetType()));
+            if (available.Length > 1)
+            {
+                var names = string.Join(", ", available.Select(v => v.GetType().Name));
+                var message = string.Concat(
+                    "Ambiguous choice between multiple validators for type ",
+					type.Name,
+					". The validators available are: ",
+					names);
+
+                throw new InvalidOperationException(message);
+            }
+
+            return available.FirstOrDefault();
         }
 
         private static Type CreateValidatorType(Type type)