Implement ShouldUseConstructor

docs/Construction.md

@@ -41,8 +41,15 @@ Mapper.Initialize(cfg =>
 
 This works for both LINQ projections and in-memory mapping.
 
-You can also disable constructor mapping :    
+You can also disable constructor mapping:    
 
 ```c#
 Mapper.Initialize(cfg => cfg.DisableConstructorMapping());
 ```
+
+You can configure which constructors are considered for the destination object:
+
+```c#
+// don't map private constructors
+Mapper.Initialize(cfg => cfg.ShouldUseConstructor = ci => !ci.IsPrivate);
+```

src/AutoMapper/Configuration/IProfileConfiguration.cs

@@ -29,7 +29,7 @@ public interface IProfileConfiguration
 
         /// <summary>
         /// Specify which properties should be mapped.
-        /// By default only public properties are mapped.e
+        /// By default only public properties are mapped.
         /// </summary>
         Func<PropertyInfo, bool> ShouldMapProperty { get; }
 
@@ -39,6 +39,12 @@ public interface IProfileConfiguration
         /// </summary>
         Func<FieldInfo, bool> ShouldMapField { get; }
 
+        /// <summary>
+        /// Specify which constructors should be considered for the destination objects.
+        /// By default all constructors are considered.
+        /// </summary>
+        Func<ConstructorInfo, bool> ShouldUseConstructor { get; }
+
         string ProfileName { get; }
         IEnumerable<string> GlobalIgnores { get; }
         INamingConvention SourceMemberNamingConvention { get; }
@@ -47,4 +53,4 @@ public interface IProfileConfiguration
         IEnumerable<ITypeMapConfiguration> OpenTypeMapConfigs { get; }
         IEnumerable<ValueTransformerConfiguration> ValueTransformers { get; }
     }
-}
+}

src/AutoMapper/IProfileExpression.cs

@@ -145,6 +145,8 @@ public interface IProfileExpression
 
         Func<PropertyInfo, bool> ShouldMapProperty { get; set; }
         Func<FieldInfo, bool> ShouldMapField { get; set; }
+        Func<ConstructorInfo, bool> ShouldUseConstructor { get; set; }
+
         string ProfileName { get; }
         IMemberConfiguration AddMemberConfiguration();
         IConditionalObjectMapper AddConditionalObjectMapper();

src/AutoMapper/Profile.cs

@@ -74,6 +74,7 @@ IEnumerable<Action<PropertyMap, IMemberConfigurationExpression>> IProfileConfigu
         public bool? EnableNullPropagationForQueryMapping { get; set; }
         public Func<PropertyInfo, bool> ShouldMapProperty { get; set; }
         public Func<FieldInfo, bool> ShouldMapField { get; set; }
+        public Func<ConstructorInfo, bool> ShouldUseConstructor { get; set; }
 
         public INamingConvention SourceMemberNamingConvention { get; set; }
         public INamingConvention DestinationMemberNamingConvention { get; set; }

src/AutoMapper/ProfileMap.cs

@@ -34,6 +34,7 @@ public ProfileMap(IProfileConfiguration profile, IConfiguration configuration)
             ConstructorMappingEnabled = profile.ConstructorMappingEnabled ?? configuration?.ConstructorMappingEnabled ?? true;
             ShouldMapField = profile.ShouldMapField ?? configuration?.ShouldMapField ?? (p => p.IsPublic());
             ShouldMapProperty = profile.ShouldMapProperty ?? configuration?.ShouldMapProperty ?? (p => p.IsPublic());
+            ShouldUseConstructor = profile.ShouldUseConstructor ?? configuration?.ShouldUseConstructor ?? (c => true);
             CreateMissingTypeMaps = profile.CreateMissingTypeMaps ?? configuration?.CreateMissingTypeMaps ?? true;
             ValidateInlineMaps = profile.ValidateInlineMaps ?? configuration?.ValidateInlineMaps ?? true;
 
@@ -83,6 +84,7 @@ public ProfileMap(IProfileConfiguration profile, IConfiguration configuration)
         public string Name { get; }
         public Func<FieldInfo, bool> ShouldMapField { get; }
         public Func<PropertyInfo, bool> ShouldMapProperty { get; }
+        public Func<ConstructorInfo, bool> ShouldUseConstructor { get; }
 
         public IEnumerable<Action<PropertyMap, IMemberConfigurationExpression>> AllPropertyMapActions { get; }
         public IEnumerable<Action<TypeMap, IMappingExpression>> AllTypeMapActions { get; }
@@ -124,9 +126,9 @@ public void Configure(IConfigurationProvider configurationProvider)
         }
 
         private void BuildTypeMap(IConfigurationProvider configurationProvider, ITypeMapConfiguration config)
-        {
+        {
             var typeMap = _typeMapFactory.CreateTypeMap(config.SourceType, config.DestinationType, this);
-
+
             config.Configure(typeMap);
 
             configurationProvider.RegisterTypeMap(typeMap);
@@ -164,7 +166,7 @@ private void Configure(TypeMap typeMap, IConfigurationProvider configurationProv
             ApplyBaseMaps(typeMap, typeMap, configurationProvider);
             ApplyDerivedMaps(typeMap, typeMap, configurationProvider);
         }
-
+
         public bool IsConventionMap(TypePair types) => TypeConfigurations.Any(c => c.IsMatch(types));
 
         public TypeMap CreateConventionTypeMap(TypePair types, IConfigurationProvider configurationProvider)
@@ -177,8 +179,8 @@ public TypeMap CreateConventionTypeMap(TypePair types, IConfigurationProvider co
 
             config.Configure(typeMap);
 
-            Configure(typeMap, configurationProvider);
-
+            Configure(typeMap, configurationProvider);
+
             return typeMap;
         }
 
@@ -188,8 +190,8 @@ public TypeMap CreateInlineMap(TypePair types, IConfigurationProvider configurat
 
             typeMap.IsConventionMap = true;
 
-            Configure(typeMap, configurationProvider);
-
+            Configure(typeMap, configurationProvider);
+
             return typeMap;
         }
 
@@ -215,7 +217,7 @@ public TypeMap CreateClosedGenericTypeMap(ITypeMapConfiguration openMapConfig, T
             {
                 var neededParameters = closedMap.DestinationTypeOverride.GetGenericParameters().Length;
                 closedMap.DestinationTypeOverride = closedMap.DestinationTypeOverride.MakeGenericType(closedTypes.DestinationType.GetGenericArguments().Take(neededParameters).ToArray());
-            }
+            }
             return closedMap;
         }
 
@@ -244,30 +246,30 @@ private void ApplyBaseMaps(TypeMap derivedMap, TypeMap currentMap, IConfiguratio
         private void ApplyDerivedMaps(TypeMap baseMap, TypeMap typeMap, IConfigurationProvider configurationProvider)
         {
             foreach (var inheritedTypeMap in GetIncludedTypeMaps(typeMap.IncludedDerivedTypes, configurationProvider))
-            {
-                inheritedTypeMap.IncludeBaseTypes(typeMap.SourceType, typeMap.DestinationType);
+            {
+                inheritedTypeMap.IncludeBaseTypes(typeMap.SourceType, typeMap.DestinationType);
                 inheritedTypeMap.AddInheritedMap(baseMap);
                 ApplyDerivedMaps(baseMap, inheritedTypeMap, configurationProvider);
             }
-        }
-
+        }
+
         private static IEnumerable<TypeMap> GetIncludedTypeMaps(IEnumerable<TypePair> includedTypes, IConfigurationProvider configurationProvider)
-        {
+        {
             foreach(var pair in includedTypes)
-            {
-                var typeMap = configurationProvider.FindTypeMapFor(pair);
+            {
+                var typeMap = configurationProvider.FindTypeMapFor(pair);
                 if(typeMap != null)
-                {
+                {
                     yield return typeMap;
                 }
-                typeMap = configurationProvider.ResolveTypeMap(pair);
-                // we want the exact map the user included, but we could instantiate an open generic
+                typeMap = configurationProvider.ResolveTypeMap(pair);
+                // we want the exact map the user included, but we could instantiate an open generic
                 if(typeMap == null || typeMap.Types != pair || typeMap.IsConventionMap)
                 {
                     throw QueryMapperHelper.MissingMapException(pair);
-                }
+                }
                 yield return typeMap;
-            }
+            }
         }
     }
 }

src/AutoMapper/TypeDetails.cs

@@ -23,7 +23,7 @@ public TypeDetails(Type type, ProfileMap config)
             PublicReadAccessors = BuildPublicReadAccessors(publicReadableMembers);
             PublicWriteAccessors = BuildPublicAccessors(publicWritableMembers);
             PublicNoArgMethods = BuildPublicNoArgMethods();
-            Constructors = type.GetDeclaredConstructors().Where(ci => !ci.IsStatic).ToArray();
+            Constructors = GetAllConstructors(config.ShouldUseConstructor);
             PublicNoArgExtensionMethods = BuildPublicNoArgExtensionMethods(config.SourceExtensionMethods);
             AllMembers = PublicReadAccessors.Concat(PublicNoArgMethods).Concat(PublicNoArgExtensionMethods).ToList();
             DestinationMemberNames = AllMembers.Select(mi => new DestinationMemberName { Member = mi, Possibles = PossibleNames(mi.Name, config.Prefixes, config.Postfixes).ToArray() });
@@ -59,7 +59,9 @@ private static IEnumerable<string> PostFixes(IEnumerable<string> postfixes, stri
                     .Select(postfix => name.Remove(name.Length - postfix.Length));
         }
 
-        private static Func<MemberInfo, bool> MembersToMap(Func<PropertyInfo, bool> shouldMapProperty, Func<FieldInfo, bool> shouldMapField)
+        private static Func<MemberInfo, bool> MembersToMap(
+            Func<PropertyInfo, bool> shouldMapProperty, 
+            Func<FieldInfo, bool> shouldMapField)
         {
             return m =>
             {
@@ -70,7 +72,7 @@ private static Func<MemberInfo, bool> MembersToMap(Func<PropertyInfo, bool> shou
                     case FieldInfo field:
                         return !field.IsStatic && shouldMapField(field);
                     default:
-                        throw new ArgumentException("Should be a field or property.");
+                        throw new ArgumentException("Should be a field or a property.");
                 }
             };
         }
@@ -163,6 +165,11 @@ private IEnumerable<MemberInfo> GetAllPublicReadableMembers(Func<MemberInfo, boo
 
         private IEnumerable<MemberInfo> GetAllPublicWritableMembers(Func<MemberInfo, bool> membersToMap)
             => GetAllPublicMembers(PropertyWritable, FieldWritable, membersToMap);
+
+        private IEnumerable<ConstructorInfo> GetAllConstructors(Func<ConstructorInfo, bool> shouldUseConstructor)
+        {
+            return Type.GetDeclaredConstructors().Where(shouldUseConstructor).ToArray();
+        }
 
         private static bool PropertyReadable(PropertyInfo propertyInfo) => propertyInfo.CanRead;
 

src/AutoMapper/TypeMap.cs

@@ -182,10 +182,8 @@ public bool PassesCtorValidation()
             if (DestinationTypeToUse.IsValueType())
                 return true;
 
-            var constructors = DestinationTypeToUse
-                .GetDeclaredConstructors()
-                .Where(ci => !ci.IsStatic);
-
+            var constructors = DestinationTypeDetails.Constructors;
+
             //find a ctor with only optional args
             var ctorWithOptionalArgs = constructors.FirstOrDefault(c => c.GetParameters().All(p => p.IsOptional));
 

src/UnitTests/ShouldUseConstructor.cs

@@ -0,0 +1,160 @@
+using System.Linq;
+using Shouldly;
+using Xunit;
+
+namespace AutoMapper.UnitTests
+{
+    public class ShouldUseConstructorInternal : NonValidatingSpecBase
+    {
+        class Destination
+        {
+            internal Destination(int a, string b)
+            {
+            }
+
+            public int A { get; }
+
+            public string B { get; }
+
+            public Destination(int a)
+            {
+
+            }
+
+            private Destination()
+            {
+            }
+        }
+
+        class Source
+        {
+            public int A { get; set; }
+        }
+
+        protected override MapperConfiguration Configuration { get; } = new MapperConfiguration(
+            cfg =>
+            {
+                cfg.ShouldUseConstructor = c => c.IsAssembly;
+                cfg.CreateMap<Source, Destination>();
+            });
+
+        [Fact]
+        public void Should_only_map_internal_ctor()
+        {
+            Should.Throw<AutoMapperConfigurationException>(() =>
+                Configuration.AssertConfigurationIsValid());
+        }
+    }
+
+    public class ShouldUseConstructorPrivate : NonValidatingSpecBase
+    {
+
+        class Destination
+        {
+            private Destination(int a, string b)
+            {
+            }
+
+            public int A { get; }
+
+            public string B { get; }
+
+            internal Destination(int a)
+            {
+
+            }
+
+            public Destination()
+            {
+            }
+        }
+
+        class Source
+        {
+            public int A { get; set; }
+        }
+
+        protected override MapperConfiguration Configuration { get; } = new MapperConfiguration(
+            cfg =>
+            {
+                cfg.ShouldUseConstructor = c => c.IsPrivate;
+                cfg.CreateMap<Source, Destination>();
+            });
+
+        [Fact]
+        public void Should_only_map_private_ctor()
+        {
+            Should.Throw<AutoMapperConfigurationException>(() =>
+                Configuration.AssertConfigurationIsValid());
+        }
+    }
+
+    public class ShouldUseConstructorPublic : NonValidatingSpecBase
+    {
+        class Destination
+        {
+            public Destination(int a, string b)
+            {
+            }
+
+            public int A { get; }
+
+            public string B { get; }
+
+            internal Destination(int a)
+            {
+
+            }
+
+            private Destination()
+            {
+            }
+        }
+
+        class Source
+        {
+            public int A { get; set; }
+        }
+
+        protected override MapperConfiguration Configuration { get; } = new MapperConfiguration(
+            cfg =>
+            {
+                cfg.ShouldUseConstructor = c => c.IsPublic;
+                cfg.CreateMap<Source, Destination>();
+            });
+
+        [Fact]
+        public void Should_only_map_public_ctor()
+        {
+            Should.Throw<AutoMapperConfigurationException>(() =>
+                Configuration.AssertConfigurationIsValid());
+        }
+    }
+
+
+    public class ShouldUseConstructorDefault : AutoMapperSpecBase
+    {
+        class Destination
+        {
+            public Destination(int a, string b)
+            {
+            }
+
+            public int A { get; }
+
+            public string B { get; }
+
+            private Destination()
+            {
+            }
+        }
+
+        class Source
+        {
+            public int A { get; set; }
+        }
+
+        protected override MapperConfiguration Configuration { get; } =
+            new MapperConfiguration(cfg => { cfg.CreateMap<Source, Destination>(); });
+    }
+}