Fix nesting for objects

src/CSV.cs

@@ -361,8 +361,8 @@ internal static string ItemsToCsv(IEnumerable items, CSVSettings settings, char[
                 if (item is string)
                 {
                     s = item as string;
-                }
-                if (item is DateTime)
+                } 
+                else if (item is DateTime)
                 {
                     s = ((DateTime)item).ToString(settings.DateTimeFormat);
                 }
@@ -429,6 +429,19 @@ internal static string ItemsToCsv(IEnumerable items, CSVSettings settings, char[
                                 break;
                         }
                     }
+                    else if (itemType.IsClass && settings.NestedObjectBehavior == ObjectOptions.RecursiveSerialization)
+                    {
+                        var nestedItems = new List<object>();
+                        foreach (var field in itemType.GetFields())
+                        {
+                            nestedItems.Add(field.GetValue(item));
+                        }
+                        foreach (var prop in itemType.GetProperties())
+                        {
+                            nestedItems.Add(prop.GetValue(item, null));
+                        }
+                        s = ItemsToCsv(nestedItems, settings, riskyChars, forceQualifierTypes);
+                    }
                     else
                     {
                         s = item.ToString();

src/CSVSettings.cs

@@ -15,7 +15,7 @@ namespace CSVFile
     public enum ArrayOptions
     {
         /// <summary>
-        /// Use built-in string conversion, which renders arrays as `MyObject[]` 
+        /// Use built-in string conversion, which renders arrays as `MyNamespace.MyObject[]` 
         /// </summary>
         ToString,
 
@@ -29,6 +29,22 @@ public enum ArrayOptions
         /// </summary>
         CountItems,
 
+        /// <summary>
+        /// Serialize child arrays recursively using the same settings
+        /// </summary>
+        RecursiveSerialization,
+    }
+
+    /// <summary>
+    /// Defines the behavior of CSV Serialization when a nested object (class) is encountered
+    /// </summary>
+    public enum ObjectOptions
+    {
+        /// <summary>
+        /// Use built-in string conversion, which renders as `MyNamespace.MyObject`
+        /// </summary>
+        ToString,
+
         /// <summary>
         /// Serialize child objects recursively using the same settings
         /// </summary>
@@ -160,10 +176,15 @@ public class CSVSettings
         public string DateTimeFormat { get; set; } = "o";
 
         /// <summary>
-        /// The behavior to use when serializing a column of an array type
+        /// The behavior to use when serializing a column that is an array or enumerable type
         /// </summary>
         public ArrayOptions NestedArrayBehavior { get; set; } = ArrayOptions.ToString;
 
+        /// <summary>
+        /// The behavior to use when serializing a column that is a class
+        /// </summary>
+        public ObjectOptions NestedObjectBehavior { get; set; } = ObjectOptions.ToString;
+
         /// <summary>
         /// Standard comma-separated value (CSV) file settings
         /// </summary>

tests/SerializationTest.cs

@@ -54,6 +54,12 @@ public class TestClassThree
             public List<Guid> NullableList { get; set; }
         }
 
+        public class TestClassFour
+        {
+            public string Name { get; set; }
+            public TestClassTwo Details { get; set; }
+        }
+
         [Test]
         public void TestObjectSerialization()
         {
@@ -136,10 +142,7 @@ public void TestNullSerialization()
         }
 
         /// <summary>
-        /// Arrays and child objects aren't well suited for complex serialization within a CSV file.
-        /// However, we have options:
-        /// * ToString just converts it to "MyClass[]"
-        /// * CountItems just produces the number of elements in the array
+        /// Tests that validate whether we can serialize arrays within arrays
         /// </summary>
         [Test]
         public void TestArraySerialization()
@@ -186,6 +189,51 @@ public void TestArraySerialization()
                             + $"Test,\"a,b,c\",\"1,2,3\",\"True,False,True,False\",,NULL{Environment.NewLine}", recursiveCsv);
         }
 
+        /// <summary>
+        /// Tests that validate whether we can serialize objects within arrays
+        /// </summary>
+        [Test]
+        public void TestNestedObjectSerialization()
+        {
+            var list = new List<TestClassFour>();
+            list.Add(new TestClassFour()
+            {
+                Name = "Non-Null Test",
+                Details = new TestClassTwo()
+                {
+                    FirstColumn = "Hello World!",
+                    SecondColumn = 42,
+                    ThirdColumn = EnumTestType.Third,
+                }
+            });
+            list.Add(new TestClassFour()
+            {
+                Name = "Null Test",
+                Details = null
+            });
+
+            // Serialize to a CSV string using ToString
+            // This was the default behavior in CSVFile 3.1.2 and earlier - it's pretty ugly!
+            var options = new CSVSettings()
+            {
+                HeaderRowIncluded = true,
+                NestedObjectBehavior = ObjectOptions.ToString,
+                NullToken = "NULL",
+                AllowNull = true,
+            };
+            var toStringCsv = CSV.Serialize(list, options);
+            Assert.AreEqual($"Name,Details{Environment.NewLine}"
+                + $"Non-Null Test,CSVTestSuite.SerializationTest+TestClassTwo{Environment.NewLine}"
+                + $"Null Test,NULL{Environment.NewLine}", toStringCsv);
+
+            // Serialize to a CSV string using counts
+            options.NestedObjectBehavior = ObjectOptions.RecursiveSerialization;
+            var recursiveCsv = CSV.Serialize(list, options);
+            Assert.AreEqual($"Name,Details{Environment.NewLine}"
+                + $"Non-Null Test,\"Hello World!,42,Third\"{Environment.NewLine}"
+                + $"Null Test,NULL{Environment.NewLine}", recursiveCsv);
+        }
+
         [Test]
         public void TestCaseInsensitiveDeserializer()
         {