Bind byte array from base64 config value

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

@@ -520,6 +520,23 @@ private static bool TryConvertValue(Type type, string value, string path, out ob
                 return true;
             }
 
+            if (type == typeof(byte[]))
+            {
+                if (value is null)
+                {
+                    return true;
+                }
+                try
+                {
+                    result = Convert.FromBase64String(value);
+                }
+                catch (FormatException ex)
+                {
+                    error = new InvalidOperationException(SR.Format(SR.Error_FailedBinding, path, type), ex);
+                }
+                return true;
+            }
+
             return false;
         }
 

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

@@ -109,6 +109,11 @@ public struct ValueTypeOptions
             public string MyString { get; set; }
         }
 
+        public class ByteArrayOptions
+        {
+            public byte[] MyByteArray { get; set; }
+        }
+
         [Fact]
         public void CanBindIConfigurationSection()
         {
@@ -812,6 +817,40 @@ public void CanBindValueTypeOptions()
             Assert.Equal("hello world", options.MyString);
         }
 
+        [Fact]
+        public void CanBindByteArray()
+        {
+            var bytes = new byte[] { 1, 2, 3, 4 };
+            var dic = new Dictionary<string, string>
+            {
+                { "MyByteArray", Convert.ToBase64String(bytes) }
+            };
+            var configurationBuilder = new ConfigurationBuilder();
+            configurationBuilder.AddInMemoryCollection(dic);
+            var config = configurationBuilder.Build();
+
+            var options = config.Get<ByteArrayOptions>();
+            Assert.Equal(bytes, options.MyByteArray);
+        }
+
+        [Fact]
+        public void ExceptionWhenTryingToBindToByteArray()
+        {
+            var dic = new Dictionary<string, string>
+            {
+                { "MyByteArray", "(not a valid base64 string)" }
+            };
+            var configurationBuilder = new ConfigurationBuilder();
+            configurationBuilder.AddInMemoryCollection(dic);
+            var config = configurationBuilder.Build();
+
+            var exception = Assert.Throws<InvalidOperationException>(
+                () => config.Get<ByteArrayOptions>());
+            Assert.Equal(
+                SR.Format(SR.Error_FailedBinding, "MyByteArray", typeof(byte[])),
+                exception.Message);
+        }
+
         private interface ISomeInterface
         {
         }