205 fix mini panic (#226)

* fix mini panic

* fix mini panic

* fix mini panic

Author: apzuk3

events/attributevalue.go

@@ -18,6 +18,10 @@ type DynamoDBAttributeValue struct {
 	dataType DynamoDBDataType
 }
 
+// This struct represents DynamoDBAttributeValue which doesn't
+// implement fmt.Stringer interface and safely `fmt.Sprintf`able
+type dynamoDbAttributeValue DynamoDBAttributeValue
+
 // Binary provides access to an attribute of type Binary.
 // Method panics if the attribute is not of type Binary.
 func (av DynamoDBAttributeValue) Binary() []byte {
@@ -98,8 +102,13 @@ func (av DynamoDBAttributeValue) NumberSet() []string {
 // String provides access to an attribute of type String.
 // Method panics if the attribute is not of type String.
 func (av DynamoDBAttributeValue) String() string {
-	av.ensureType(DataTypeString)
-	return av.value.(string)
+	if av.dataType == DataTypeString {
+		return av.value.(string)
+	}
+	// If dataType is not DataTypeString during fmt.Sprintf("%#v", ...)
+	// compiler confuses with fmt.Stringer interface and panics
+	// instead of printing the struct.
+	return fmt.Sprintf("%v", dynamoDbAttributeValue(av))
 }
 
 // StringSet provides access to an attribute of type String Set.