feat: Ability to filter handling of a ValidationException by the erro…

…r filter

README.md

@@ -84,6 +84,11 @@ Some of the default implementations are defined publicly on the default options
 Errors will be written out into the GraphQL execution result in the `Errors` property. By default, 
 extra information about the validation will be written out in the Extensions property. 
 
+This is handled by the `ValidationErrorFilter`.
+
+If you need to selectively ignore some `ValidationException` instances,
+you can provide your own predicate function to `ValidationErrorFilter` via the constructor.
+
 For example:
 
 > (note, this is the serialized `IExecutionResult`, not a GraphQL server response)
@@ -140,6 +145,13 @@ public class UserInputValidator : AbstractValidator<UserInput>, IRequiresOwnScop
 }
 ```
 
+### Using MediatR for firing validation?
+
+If you're using [MediatR](https://github.com/jbogard/MediatR) for firing validation, no worries!
+
+If your MediatR pipeline behaviour throws a `FluentValidation.ValidationException` you can still use FairyBread's
+`DefaultValidationErrorFilter` as mentioned earlier to rewrite it on the way out into a friendlier error for the client.
+
 ### Where to next?
 
 For more examples, please see the tests.

src/Directory.Build.props

@@ -14,7 +14,7 @@
     <PackageId>$(MSBuildProjectName)</PackageId>
     <PackageIconUrl>https://github.com/benmccallum/fairybread/raw/master/logo-400x400.png</PackageIconUrl>
 
-    <Version>1.0.0-preview.9</Version>
+    <Version>1.0.0</Version>
 
     <HotChocolateVersion>10.5.2</HotChocolateVersion>
   </PropertyGroup>

src/FairyBread.Tests/CustomizationTests.cs

@@ -46,7 +46,7 @@ private IQueryExecutor InitQueryExecutor(Action<IServiceCollection> preBuildProv
             {
                 builder
                     .UseDefaultPipeline()
-                    .AddErrorFilter<DefaultValidationErrorFilter>();
+                    .AddErrorFilter<ValidationErrorFilter>();
             });
         }
 

src/FairyBread.Tests/DefaultValidationErrorFilterTests.cs

@@ -0,0 +1,80 @@
+using System;
+using System.Collections.Generic;
+using FluentValidation;
+using HotChocolate;
+using Moq;
+using Xunit;
+
+namespace FairyBread.Tests
+{
+    public class DefaultValidationErrorFilterTests
+    {
+        [Fact]
+        public void Should_Handle_ValidationException()
+        {
+            // Arrange
+            var error = new AnError().WithException(new ValidationException("some msg"));
+
+            var defaultValidationErrorFilter = new ValidationErrorFilter();
+
+            // Act / Assert
+            Assert.Throws<NotImplementedException>(() => defaultValidationErrorFilter.OnError(error));
+        }
+
+        [Fact]
+        public void Should_Ignore_OtherException()
+        {
+            // Arrange
+            var error = new AnError().WithException(new Exception("some msg"));
+
+            var defaultValidationErrorFilter = new ValidationErrorFilter();
+
+            // Act / Assert
+            defaultValidationErrorFilter.OnError(error);
+        }
+
+        [Fact]
+        public void Should_Ignore_CertainValidationException()
+        {
+            // Arrange
+            var error = new AnError().WithException(new Exception("some msg"));
+
+            var defaultValidationErrorFilter = new ValidationErrorFilter(ex => false);
+
+            // Act / Assert
+            defaultValidationErrorFilter.OnError(error);
+        }
+
+        class AnError : IError
+        {
+            public string Message => throw new NotImplementedException();
+
+            public string Code => throw new NotImplementedException();
+
+            public IReadOnlyList<object> Path => throw new NotImplementedException();
+
+            public IReadOnlyList<Location> Locations => throw new NotImplementedException();
+
+            private Exception? _exception;
+            public Exception? Exception => _exception;
+
+            public IReadOnlyDictionary<string, object> Extensions => throw new NotImplementedException();
+
+            public IError AddExtension(string key, object value) => throw new NotImplementedException();
+            public IError RemoveException() => throw new NotImplementedException();
+            public IError RemoveExtension(string key) => throw new NotImplementedException();
+            public IError WithCode(string code) => throw new NotImplementedException();
+            public IError WithException(Exception exception)
+            {
+                _exception = exception;
+                return this;
+            }
+
+            public IError WithExtensions(IReadOnlyDictionary<string, object> extensions) => throw new NotImplementedException();
+            public IError WithLocations(IReadOnlyList<Location> locations) => throw new NotImplementedException();
+            public IError WithMessage(string message) => throw new NotImplementedException();
+            public IError WithPath(Path path) => throw new NotImplementedException();
+            public IError WithPath(IReadOnlyList<object> path) => throw new NotImplementedException();
+        }
+    }
+}

src/FairyBread.Tests/InputValidationMiddlewareTests.cs

@@ -43,7 +43,7 @@ private IQueryExecutor GetQueryExecutor(Action<IFairyBreadOptions>? configureOpt
             {
                 builder
                     .UseDefaultPipeline()
-                    .AddErrorFilter<DefaultValidationErrorFilter>();
+                    .AddErrorFilter<ValidationErrorFilter>();
             });
         }
 
@@ -133,7 +133,7 @@ public async Task Mutation_Works(CaseData caseData)
             {
                 builder
                     .UseDefaultPipeline()
-                    .AddErrorFilter<DefaultValidationErrorFilter>();
+                    .AddErrorFilter<ValidationErrorFilter>();
             });
 
             // Act

src/FairyBread.Tests/RequiresOwnScopeValidatorTests.cs

@@ -43,7 +43,7 @@ private IQueryExecutor InitQueryExecutor(Action<IServiceCollection> preBuildProv
             {
                 builder
                     .UseDefaultPipeline()
-                    .AddErrorFilter<DefaultValidationErrorFilter>();
+                    .AddErrorFilter<ValidationErrorFilter>();
             });
         }
 

src/FairyBread.Tests/ValidateDescriptorTests.cs

@@ -21,7 +21,7 @@ private IQueryExecutor InitQueryExecutor()
             services.AddFairyBread(options =>
             {
                 options.AssembliesToScanForValidators = new[] { typeof(FooInputDtoValidator).Assembly };
-                options.ShouldValidate = DefaultFairyBreadOptions.ShouldValidateBasedOnValidateDescriptorImplementation;
+                options.ShouldValidate = DefaultFairyBreadOptions.DefaultImplementations.ShouldValidateBasedOnValidateDescriptor;
             });
 
             var serviceProvider = services.BuildServiceProvider();
@@ -42,7 +42,7 @@ private IQueryExecutor InitQueryExecutor()
             {
                 builder
                     .UseDefaultPipeline()
-                    .AddErrorFilter<DefaultValidationErrorFilter>();
+                    .AddErrorFilter<ValidationErrorFilter>();
             });
         }
 

src/FairyBread/DefaultFairyBreadOptions.cs

@@ -1,5 +1,4 @@
 using System;
-using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.Linq;
 using System.Reflection;
@@ -15,61 +14,113 @@ public class DefaultFairyBreadOptions : IFairyBreadOptions
 
         public virtual bool ThrowIfNoValidatorsFound { get; set; } = true;
 
-        public virtual Func<IMiddlewareContext, Argument, bool> ShouldValidate { get; set; } = ShouldValidateImplementation;
+        /// <inheritdoc/>
+        public virtual Func<IMiddlewareContext, Argument, bool> ShouldValidate { get; set; }
+            = DefaultImplementations.ShouldValidate;
 
-        public static bool ShouldValidateImplementation(IMiddlewareContext context, Argument argument)
+        /// <summary>
+        /// Default implementations of some things that can be re-composed as needed.
+        /// </summary>
+        public static class DefaultImplementations
         {
-            // If a mutation operation and this is an input object
-            if (context.Operation.Operation == OperationType.Mutation &&
-                argument.Type.InnerType() is InputObjectType)
+            /// <summary>
+            /// By default, FairyBread will validate any argument that:
+            /// <list type="bullet">
+            ///     <item>
+            ///         <description>
+            ///             is an InputObjectType on a mutation operation,
+            ///         </description>
+            ///     </item>
+            ///     <item>
+            ///         <description>
+            ///             is manually opted-in at the field level with:
+            ///             <list type="bullet">
+            ///                 <item><description>
+            ///                     [Validate] on the resolver method argument in pure code first
+            ///                 </description></item>
+            ///                 <item><description>
+            ///                     .UseValidation() on the argument definition in code first
+            ///                 </description></item>
+            ///             </list>
+            ///         </description>
+            ///     </item>
+            ///     <item>
+            ///         <description>
+            ///             is manually opted-in at the input type level with:
+            ///             <list type="bullet">
+            ///                 <item><description>
+            ///                     [Validate] on the CLR backing type in pure code first
+            ///                 </description></item>
+            ///                 <item><description>
+            ///                     .UseValidation() on the InputObjectType descriptor in code first
+            ///                 </description></item>
+            ///             </list>
+            ///         </description>
+            ///     </item>
+            ///     <item>
+            ///        <description>
+            ///            
+            ///        </description>
+            ///     </item>
+            /// </list>
+            /// </summary>
+            /// <remarks>
+            /// More at: https://github.com/benmccallum/fairybread#when-validation-will-fire
+            /// </remarks>
+            public static bool ShouldValidate(IMiddlewareContext context, Argument argument)
             {
-                return true;
+                // If a mutation operation and this is an input object
+                if (context.Operation.Operation == OperationType.Mutation &&
+                    argument.Type.InnerType() is InputObjectType)
+                {
+                    return true;
+                }
+
+                if (ShouldValidateBasedOnValidateDescriptor(context, argument))
+                {
+                    return true;
+                }
+
+                return false;
             }
 
-            if (ShouldValidateBasedOnValidateDescriptorImplementation(context, argument))
+            public static bool ShouldValidateBasedOnValidateDescriptor(IMiddlewareContext context, Argument argument)
             {
-                return true;
-            }
+                // If argument itself was annotated
+                if (IsValidateDescriptorApplied(argument.ContextData))
+                {
+                    return true;
+                }
 
-            return false;
-        }
+                // If argument's input type was annotated
+                if (argument.Type.InnerType() is InputObjectType inputType &&
+                    IsValidateDescriptorApplied(inputType))
+                {
+                    return true;
+                }
 
-        public static bool ShouldValidateBasedOnValidateDescriptorImplementation(IMiddlewareContext context, Argument argument)
-        {
-            // If argument itself was annotated
-            if (IsValidateDescriptorApplied(argument.ContextData))
-            {
-                return true;
+                // If argument's clr type was annotated
+                if (ClrTypesMarkedWithValidate.Cache.GetOrAdd(
+                        argument.ClrType,
+                        clrType => clrType.GetCustomAttribute<ValidateAttribute>(inherit: true) != null))
+                {
+                    return true;
+                }
+
+                return false;
             }
 
-            // If argument's input type was annotated
-            if (argument.Type.InnerType() is InputObjectType inputType &&
-                IsValidateDescriptorApplied(inputType))
+            private static bool IsValidateDescriptorApplied(IHasContextData thing)
             {
-                return true;
+                return IsValidateDescriptorApplied(thing.ContextData);
             }
 
-            // If argument's clr type was annotated
-            if (ClrTypesMarkedWithValidate.Cache.GetOrAdd(
-                    argument.ClrType,
-                    clrType => clrType.GetCustomAttribute<ValidateAttribute>(inherit: true) != null))
+            private static bool IsValidateDescriptorApplied(IReadOnlyDictionary<string, object?> contextData)
             {
-                return true;
+                return contextData.TryGetValue(ValidateAttribute.ValidateContextDataKey, out var isValidateDescriptorAppliedRaw) &&
+                   isValidateDescriptorAppliedRaw is bool isValidateDescriptorApplied &&
+                   isValidateDescriptorApplied;
             }
-
-            return false;
-        }
-
-        private static bool IsValidateDescriptorApplied(IHasContextData thing)
-        {
-            return IsValidateDescriptorApplied(thing.ContextData);
-        }
-
-        private static bool IsValidateDescriptorApplied(IReadOnlyDictionary<string, object?> contextData)
-        {
-            return contextData.TryGetValue(ValidateAttribute.ValidateContextDataKey, out var isValidateDescriptorAppliedRaw) &&
-               isValidateDescriptorAppliedRaw is bool isValidateDescriptorApplied &&
-               isValidateDescriptorApplied;
         }
     }
 }

src/FairyBread/IFairyBreadOptions.cs

@@ -1,4 +1,5 @@
-using HotChocolate.Resolvers;
+using FluentValidation;
+using HotChocolate.Resolvers;
 using HotChocolate.Types;
 using System;
 using System.Collections.Generic;
@@ -12,6 +13,11 @@ public interface IFairyBreadOptions
 
         bool ThrowIfNoValidatorsFound { get; set; }
 
+        /// <summary>
+        /// Function used to determine if an argument should be validated by
+        /// FairyBread's <see cref="InputValidationMiddleware"/>.
+        /// The default implementation is <see cref="DefaultImplementations.ShouldValidate(IMiddlewareContext, Argument)"/>
+        /// </summary>
         Func<IMiddlewareContext, Argument, bool> ShouldValidate { get; set; }
     }
 }

src/FairyBread/DefaultValidationErrorFilter.cs → src/FairyBread/ValidationErrorFilter.cs

@@ -1,16 +1,34 @@
-using System.Linq;
+using System;
+using System.Linq;
 using FluentValidation;
 using FluentValidation.Results;
 using HotChocolate;
 
 namespace FairyBread
 {
-    public class DefaultValidationErrorFilter : IErrorFilter
+    public class ValidationErrorFilter : IErrorFilter
     {
+        /// <summary>
+        /// Function used to determine if an <see cref="IError"/> with a <see cref="ValidationException"/>
+        /// should be handled and rewritten.
+        /// </summary>
+        private Func<ValidationException, bool> _shouldHandleValidationExceptionPredicate { get; set; } = ex => true;
+
+        public ValidationErrorFilter()
+        {
+
+        }
+
+        public ValidationErrorFilter(Func<ValidationException, bool> shouldHandleValidationExceptionPredicate)
+        {
+            _shouldHandleValidationExceptionPredicate = shouldHandleValidationExceptionPredicate;
+        }
+
         public IError OnError(IError error)
         {
             if (error.Exception != null &&
-                error.Exception is ValidationException validationException)
+                error.Exception is ValidationException validationException &&
+                _shouldHandleValidationExceptionPredicate(validationException))
             {
                 return OnValidationException(error, validationException);
             }