fix empty strings as null AttributeValue issue

Author: irina-herciu

.autover/67579ff1-ffb8-4d48-83a8-b774555ec8e8.json

@@ -0,0 +1,11 @@
+{
+  "Projects": [
+    {
+      "Name": "Amazon.Lambda.DynamoDBEvents.SDK.Convertor",
+      "Type": "Patch",
+      "ChangelogMessages": [
+        "Fix Empty Strings converted to null issue."
+      ]
+    }
+  ]
+}

Libraries/src/Amazon.Lambda.DynamoDBEvents.SDK.Convertor/DynamodbAttributeValueConvertor.cs

@@ -21,7 +21,7 @@ public static Amazon.DynamoDBv2.Model.AttributeValue ConvertToSdkAttribute(this
             var sdkAttribute = new Amazon.DynamoDBv2.Model.AttributeValue();
 
             // String
-            if (!string.IsNullOrEmpty(lambdaAttribute.S))
+            if (lambdaAttribute.S!=null)
                 sdkAttribute.S = lambdaAttribute.S;
 
             // Number
@@ -112,7 +112,7 @@ public static Amazon.DynamoDBStreams.Model.AttributeValue ConvertToSdkStreamAttr
             var sdkAttribute = new Amazon.DynamoDBStreams.Model.AttributeValue();
 
             // String
-            if (!string.IsNullOrEmpty(lambdaAttribute.S))
+            if (lambdaAttribute.S != null)
                 sdkAttribute.S = lambdaAttribute.S;
 
             // Number

Libraries/test/Amazon.Lambda.DynamoDBEvents.SDK.Convertor.Tests/DynamodbAttributeValueConvertorTests.cs

@@ -12,6 +12,16 @@ public void ConvertToSdkAttribute_StringValue_ReturnsSdkAttribute()
             Assert.Equal("TestString", sdkAttribute.S);
         }
 
+        [Fact]
+        public void ConvertToSdkAttribute_EmptyStringValue_ReturnsSdkAttribute()
+        {
+            var lambdaAttribute = new DynamoDBEvent.AttributeValue { S = string.Empty };
+            var sdkAttribute = lambdaAttribute.ConvertToSdkAttribute();
+
+            Assert.NotNull(sdkAttribute);
+            Assert.Equal(string.Empty, sdkAttribute.S);
+        }
+
         [Fact]
         public void ConvertToSdkAttribute_NumberValue_ReturnsSdkAttribute()
         {