Add ConfigurationKeyNameAttribute to binder and updated tests.

src/libraries/Microsoft.Extensions.Configuration.Abstractions/ref/Microsoft.Extensions.Configuration.Abstractions.cs

@@ -4,8 +4,17 @@
 // Changes to this file must follow the https://aka.ms/api-review process.
 // ------------------------------------------------------------------------------
 
+using System;
+
 namespace Microsoft.Extensions.Configuration
 {
+    [AttributeUsage(AttributeTargets.Field | AttributeTargets.Property)]
+    public sealed class ConfigurationKeyNameAttribute : Attribute
+    {
+        public ConfigurationKeyNameAttribute(string name) => Name = name;
+
+        public string Name { get; }
+    }
     public static partial class ConfigurationExtensions
     {
         public static Microsoft.Extensions.Configuration.IConfigurationBuilder Add<TSource>(this Microsoft.Extensions.Configuration.IConfigurationBuilder builder, System.Action<TSource> configureSource) where TSource : Microsoft.Extensions.Configuration.IConfigurationSource, new() { throw null; }

src/libraries/Microsoft.Extensions.Configuration.Abstractions/src/ConfigurationKeyNameAttribute.cs

@@ -0,0 +1,15 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System;
+
+namespace Microsoft.Extensions.Configuration
+{
+    [AttributeUsage(AttributeTargets.Field | AttributeTargets.Property)]
+    public sealed class ConfigurationKeyNameAttribute : Attribute
+    {
+        public ConfigurationKeyNameAttribute(string name) => Name = name;
+
+        public string Name { get; }
+    }
+}

src/libraries/Microsoft.Extensions.Configuration.Binder/src/ConfigurationBinder.cs

@@ -208,7 +208,7 @@ private static void BindProperty(PropertyInfo property, object instance, IConfig
                 return;
             }
 
-            propertyValue = BindInstance(property.PropertyType, propertyValue, config.GetSection(property.Name), options);
+            propertyValue = GetPropertyValue(property, instance, config, options);
 
             if (propertyValue != null && hasSetter)
             {
@@ -575,5 +575,42 @@ private static IEnumerable<PropertyInfo> GetAllProperties(Type type)
 
             return allProperties;
         }
+
+        private static object GetPropertyValue(PropertyInfo property, object instance, IConfiguration config, BinderOptions options)
+        {
+            object propertyValue = property.GetValue(instance);
+            string propertyName = GetPropertyAttributeKeyName(property);
+
+            if (string.IsNullOrEmpty(propertyName))
+            {
+                propertyName = property.Name;
+            }
+
+            return BindInstance(property.PropertyType, propertyValue, config.GetSection(propertyName), options);
+        }
+
+        private static string GetPropertyAttributeKeyName(MemberInfo property)
+        {
+            if (property == null)
+            {
+                return string.Empty;
+            }
+
+            foreach (var attributeData in property.GetCustomAttributesData())
+            {
+                if (attributeData.AttributeType != typeof(ConfigurationKeyNameAttribute))
+                {
+                    continue;
+                }
+
+                var constructorArgument = attributeData.ConstructorArguments.FirstOrDefault();
+                if (constructorArgument.ArgumentType == typeof(string))
+                {
+                    return constructorArgument.Value?.ToString() ?? string.Empty;
+                }
+            }
+
+            return string.Empty;
+        }
     }
 }

src/libraries/Microsoft.Extensions.Configuration.Binder/tests/ConfigurationBinderTests.cs

@@ -34,6 +34,10 @@ public ComplexOptions()
             internal string InternalProperty { get; set; }
             protected string ProtectedProperty { get; set; }
 
+
+            [ConfigurationKeyName("Named_Property")]
+            public string NamedProperty { get; set; }
+
             protected string ProtectedPrivateSet { get; private set; }
 
             private string PrivateReadOnly { get; }
@@ -201,6 +205,36 @@ public void CanBindIConfigurationSectionWithDerivedOptionsSection()
             Assert.Null(options.Section.Value);
         }
 
+        [Fact]
+        public void CanBindAttributesIConfigurationSection()
+        {
+            var dic = new Dictionary<string, string>
+            {
+                {"Section:Integer", "-2"},
+                {"Section:Boolean", "TRUe"},
+                {"Section:Nested:Integer", "11"},
+                {"Section:Virtual", "Sup"},
+                {"Section:Named_Property", "Yo"},
+            };
+            var configurationBuilder = new ConfigurationBuilder();
+            configurationBuilder.AddInMemoryCollection(dic);
+            var config = configurationBuilder.Build();
+
+            var options = config.Get<ConfigurationInterfaceOptions>();
+
+            var childOptions = options.Section.Get<DerivedOptions>();
+
+            Assert.True(childOptions.Boolean);
+            Assert.Equal(-2, childOptions.Integer);
+            Assert.Equal(11, childOptions.Nested.Integer);
+            Assert.Equal("Derived:Sup", childOptions.Virtual);
+            Assert.Equal("Yo", childOptions.NamedProperty);
+
+            Assert.Equal("Section", options.Section.Key);
+            Assert.Equal("Section", options.Section.Path);
+            Assert.Null(options.Section.Value);
+        }
+
         [Fact]
         public void EmptyStringIsNullable()
         {