Merge branch 'feature-1198' of github.com:micheleissa/CsvHelper into …

…micheleissa-feature-1198

src/CsvHelper/Configuration/MemberMap.cs

@@ -212,16 +212,31 @@ public virtual MemberMap Optional()
 		/// </summary>
 		/// <param name="validateExpression"></param>
 		public virtual MemberMap Validate(Validate validateExpression)
+		{
+			return Validate(validateExpression, args => $"Field '{args.Field}' is not valid.");
+		}
+
+		/// <summary>
+		/// Specifies an expression to be used to validate a field when reading along with specified exception message.
+		/// </summary>
+		/// <param name="validateExpression"></param>
+		/// <param name="validateMessageExpression"></param>
+		public virtual MemberMap Validate(Validate validateExpression, ValidateMessage validateMessageExpression)
 		{
 			var fieldParameter = Expression.Parameter(typeof(ValidateArgs), "field");
-			var methodExpression = Expression.Call(
+			var validateCallExpression = Expression.Call(
 				Expression.Constant(validateExpression.Target),
 				validateExpression.Method,
 				fieldParameter
 			);
-			var lambdaExpression = Expression.Lambda<Validate>(methodExpression, fieldParameter);
+			var messageCallExpression = Expression.Call(
+				Expression.Constant(validateMessageExpression.Target),
+				validateMessageExpression.Method,
+				fieldParameter
+			);
 
-			Data.ValidateExpression = lambdaExpression;
+			Data.ValidateExpression = Expression.Lambda<Validate>(validateCallExpression, fieldParameter);
+			Data.ValidateMessageExpression = Expression.Lambda<ValidateMessage>(messageCallExpression, fieldParameter);
 
 			return this;
 		}

src/CsvHelper/Configuration/MemberMapData.cs

@@ -145,12 +145,17 @@ public virtual Type Type
 		/// </summary>
 		public virtual Expression ValidateExpression { get; set; }
 
+		/// <summary>
+		/// Gets or sets the expression used to get the validation message when validation fails.
+		/// </summary>
+		public virtual Expression ValidateMessageExpression { get; set; }
+
 		/// <summary>
 		/// Gets or sets a value indicating if a field is optional.
 		/// </summary>
 		public virtual bool IsOptional { get; set; }
 
-		/// <summary>
+        /// <summary>
 		/// Initializes a new instance of the <see cref="MemberMapData"/> class.
 		/// </summary>
 		/// <param name="member">The member.</param>

src/CsvHelper/Configuration/MemberMap`1.cs

@@ -35,7 +35,7 @@ public MemberMap(MemberInfo? member)
 		/// The first name will be used.
 		/// </summary>
 		/// <param name="names">The possible names of the CSV field.</param>
-		public virtual new MemberMap<TClass, TMember> Name(params string[] names)
+		public new virtual MemberMap<TClass, TMember> Name(params string[] names)
 		{
 			if (names == null || names.Length == 0)
 			{
@@ -55,7 +55,7 @@ public MemberMap(MemberInfo? member)
 		/// are multiple names that are the same.
 		/// </summary>
 		/// <param name="index">The index of the name.</param>
-		public virtual new MemberMap<TClass, TMember> NameIndex(int index)
+		public new virtual MemberMap<TClass, TMember> NameIndex(int index)
 		{
 			Data.NameIndex = index;
 
@@ -70,7 +70,7 @@ public MemberMap(MemberInfo? member)
 		/// </summary>
 		/// <param name="index">The index of the CSV field.</param>
 		/// <param name="indexEnd">The end index used when mapping to an <see cref="IEnumerable"/> member.</param>
-		public virtual new MemberMap<TClass, TMember> Index(int index, int indexEnd = -1)
+		public new virtual MemberMap<TClass, TMember> Index(int index, int indexEnd = -1)
 		{
 			Data.Index = index;
 			Data.IsIndexSet = true;
@@ -86,7 +86,7 @@ public MemberMap(MemberInfo? member)
 		/// this method will not ignore all the child members down the
 		/// tree that have already been mapped.
 		/// </summary>
-		public virtual new MemberMap<TClass, TMember> Ignore()
+		public new virtual MemberMap<TClass, TMember> Ignore()
 		{
 			Data.Ignore = true;
 
@@ -101,7 +101,7 @@ public MemberMap(MemberInfo? member)
 		/// tree that have already been mapped.
 		/// </summary>
 		/// <param name="ignore">True to ignore, otherwise false.</param>
-		public virtual new MemberMap<TClass, TMember> Ignore(bool ignore)
+		public new virtual MemberMap<TClass, TMember> Ignore(bool ignore)
 		{
 			Data.Ignore = ignore;
 
@@ -159,7 +159,7 @@ public virtual MemberMap<TClass, TMember> Constant(TMember? constantValue)
 		/// when converting the member to and from a CSV field.
 		/// </summary>
 		/// <param name="typeConverter">The TypeConverter to use.</param>
-		public virtual new MemberMap<TClass, TMember> TypeConverter(ITypeConverter typeConverter)
+		public new virtual MemberMap<TClass, TMember> TypeConverter(ITypeConverter typeConverter)
 		{
 			Data.TypeConverter = typeConverter;
 
@@ -172,7 +172,7 @@ public virtual MemberMap<TClass, TMember> Constant(TMember? constantValue)
 		/// </summary>
 		/// <typeparam name="TConverter">The <see cref="System.Type"/> of the 
 		/// <see cref="TypeConverter"/> to use.</typeparam>
-		public virtual new MemberMap<TClass, TMember> TypeConverter<TConverter>() where TConverter : ITypeConverter
+		public new virtual MemberMap<TClass, TMember> TypeConverter<TConverter>() where TConverter : ITypeConverter
 		{
 			TypeConverter(ObjectResolver.Current.Resolve<TConverter>());
 
@@ -226,7 +226,7 @@ public virtual MemberMap<TClass, TMember> Convert(ConvertToString<TClass> conver
 		/// <summary>
 		/// Ignore the member when reading if no matching field name can be found.
 		/// </summary>
-		public virtual new MemberMap<TClass, TMember> Optional()
+		public new virtual MemberMap<TClass, TMember> Optional()
 		{
 			Data.IsOptional = true;
 
@@ -237,17 +237,32 @@ public virtual MemberMap<TClass, TMember> Convert(ConvertToString<TClass> conver
 		/// Specifies an expression to be used to validate a field when reading.
 		/// </summary>
 		/// <param name="validateExpression"></param>
-		public virtual new MemberMap<TClass, TMember> Validate(Validate validateExpression)
+		public new virtual MemberMap<TClass, TMember> Validate(Validate validateExpression)
+		{
+			return Validate(validateExpression, args => $"Field '{args.Field}' is not valid.");
+		}
+
+		/// <summary>
+		/// Specifies an expression to be used to validate a field when reading along with specified exception message.
+		/// </summary>
+		/// <param name="validateExpression"></param>
+		/// <param name="validateMessageExpression"></param>
+		public new virtual MemberMap<TClass, TMember> Validate(Validate validateExpression, ValidateMessage validateMessageExpression)
 		{
 			var fieldParameter = Expression.Parameter(typeof(ValidateArgs), "args");
-			var methodExpression = Expression.Call(
+			var validateCallExpression = Expression.Call(
 				Expression.Constant(validateExpression.Target),
 				validateExpression.Method,
 				fieldParameter
 			);
-			var lambdaExpression = Expression.Lambda<Validate>(methodExpression, fieldParameter);
+			var messageCallExpression = Expression.Call(
+				Expression.Constant(validateMessageExpression.Target),
+				validateMessageExpression.Method,
+				fieldParameter
+			);
 
-			Data.ValidateExpression = lambdaExpression;
+			Data.ValidateExpression = Expression.Lambda<Validate>(validateCallExpression, fieldParameter);
+			Data.ValidateMessageExpression = Expression.Lambda<ValidateMessage>(messageCallExpression, fieldParameter);
 
 			return this;
 		}

src/CsvHelper/Delegates/Validate.cs

@@ -17,6 +17,13 @@ namespace CsvHelper
 	/// <returns><c>true</c> if the field is valid, otherwise <c>false</c>.</returns>
 	public delegate bool Validate(ValidateArgs args);
 
+	/// <summary>
+	/// Function that gets the exception message when validation fails.
+	/// </summary>
+	/// <param name="args">The args.</param>
+	/// <returns>The exception message.</returns>
+	public delegate string ValidateMessage(ValidateArgs args);
+
 	/// <summary>
 	/// Validate args.
 	/// </summary>
@@ -27,13 +34,20 @@ public readonly struct ValidateArgs
 		/// </summary>
 		public readonly string Field;
 
+		/// <summary>
+		/// The row.
+		/// </summary>
+		public readonly IReaderRow Row;
+
 		/// <summary>
 		/// Creates a new instance of ValidateArgs.
 		/// </summary>
 		/// <param name="field">The field.</param>
-		public ValidateArgs(string field)
+		/// <param name="row">The row.</param>
+		public ValidateArgs(string field, IReaderRow row)
 		{
 			Field = field;
+			Row = row;
 		}
 	}
 }

src/CsvHelper/Expressions/ExpressionManager.cs

@@ -253,11 +253,12 @@ public virtual void CreateMemberAssignmentsForMapping(ClassMap mapping, List<Mem
 			// Validate the field.
 			if (memberMap.Data.ValidateExpression != null)
 			{
-				var constructor = typeof(ValidateArgs).GetConstructor(new Type[] { typeof(string) });
-				var args = Expression.New(constructor, fieldExpression);
+				var constructor = typeof(ValidateArgs).GetConstructor(new Type[] { typeof(string), typeof(IReaderRow) });
+				var args = Expression.New(constructor, fieldExpression, Expression.Constant(reader));
 				var validateExpression = Expression.IsFalse(Expression.Invoke(memberMap.Data.ValidateExpression, args));
-				var validationExceptionConstructor = typeof(FieldValidationException).GetConstructors().OrderBy(c => c.GetParameters().Length).First();
-				var newValidationExceptionExpression = Expression.New(validationExceptionConstructor, Expression.Constant(reader.Context), fieldExpression);
+				var validationExceptionConstructor = typeof(FieldValidationException).GetConstructor(new Type[] { typeof(CsvContext), typeof(string), typeof(string) });
+				var messageExpression = Expression.Invoke(memberMap.Data.ValidateMessageExpression, args);
+				var newValidationExceptionExpression = Expression.New(validationExceptionConstructor, Expression.Constant(reader.Context), fieldExpression, messageExpression);
 				var throwExpression = Expression.Throw(newValidationExceptionExpression);
 				fieldExpression = Expression.Block(
 					// If the validate method returns false, throw an exception.

tests/CsvHelper.Tests/Reading/ValidateTests.cs

@@ -3,15 +3,15 @@
 // See LICENSE.txt for details or visit http://www.opensource.org/licenses/ms-pl.html for MS-PL and http://opensource.org/licenses/Apache-2.0 for Apache 2.0.
 // https://github.com/JoshClose/CsvHelper
 using CsvHelper.Configuration;
-using Xunit;
 using System.Globalization;
 using System.IO;
 using System.Linq;
 using System.Text;
+using Xunit;
 
 namespace CsvHelper.Tests.Reading
 {
-	
+
 	public class ValidateTests
 	{
 		[Fact]
@@ -108,6 +108,24 @@ public void CustomExceptionTest()
 			}
 		}
 
+		[Fact]
+		public void ValidateMessageTest()
+		{
+			var config = new CsvConfiguration(CultureInfo.InvariantCulture)
+			{
+			};
+			var s = new TestStringBuilder(config.NewLine);
+			s.AppendLine("Id,Name");
+			s.AppendLine("1,one");
+			using (var reader = new StringReader(s))
+			using (var csv = new CsvReader(reader, config))
+			{
+				csv.Context.RegisterClassMap<ValidationMessageMap>();
+				var exception = Assert.Throws<FieldValidationException>(() => csv.GetRecords<Test>().ToList());
+				Assert.StartsWith("Field 'one' was not foo.", exception.Message);
+			}
+		}
+
 		private class Test
 		{
 			public int Id { get; set; }
@@ -142,15 +160,15 @@ public LogInsteadMap(StringBuilder logger)
 			{
 				Map(m => m.Id);
 				Map(m => m.Name).Validate(args =>
-			 {
-				 var isValid = !string.IsNullOrEmpty(args.Field);
-				 if (!isValid)
-				 {
-					 logger.AppendLine($"Field '{args.Field}' is not valid!");
-				 }
-
-				 return true;
-			 });
+				{
+					var isValid = !string.IsNullOrEmpty(args.Field);
+					if (!isValid)
+					{
+						logger.AppendLine($"Field '{args.Field}' is not valid!");
+					}
+
+					return true;
+				});
 			}
 		}
 
@@ -166,5 +184,14 @@ public CustomExceptionMap()
 		private class CustomException : CsvHelperException
 		{
 		}
+
+		private class ValidationMessageMap : ClassMap<Test>
+		{
+			public ValidationMessageMap()
+			{
+				Map(m => m.Id);
+				Map(m => m.Name).Validate(args => args.Field == "foo", args => $"Field '{args.Field}' was not foo.");
+			}
+		}
 	}
 }