Add support for serializing single Dictionary or KVP[] to CSV

Author: mythz

src/ServiceStack.Text/CsvSerializer.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Collections;
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;
@@ -256,6 +257,13 @@ private static WriteObjectDelegate GetWriteFn()
             bestCandidateEnumerableType = typeof(T).GetTypeWithGenericTypeDefinitionOf(typeof(IEnumerable<>));
             if (bestCandidateEnumerableType != null)
             {
+                var dictionarOrKvps = typeof(T).HasInterface(typeof(IEnumerable<KeyValuePair<string, object>>))
+                                   || typeof(T).HasInterface(typeof(IEnumerable<KeyValuePair<string, string>>));
+                if (dictionarOrKvps)
+                {
+                    return WriteSelf;
+                }
+
                 var elementType = bestCandidateEnumerableType.GenericTypeArguments()[0];
                 writeElementFn = CreateWriteFn(elementType);
 

src/ServiceStack.Text/CsvWriter.cs

@@ -32,6 +32,36 @@ public static void WriteObjectRow(TextWriter writer, IEnumerable<object> row)
             writer.Write(CsvConfig.RowSeparatorString);
         }
 
+        public static void Write(TextWriter writer, IEnumerable<KeyValuePair<string, object>> records)
+        {
+            if (records == null) return; //AOT
+
+            var requireHeaders = !CsvConfig<IEnumerable<KeyValuePair<string, object>>>.OmitHeaders;
+            if (requireHeaders)
+            {
+                var keys = records.Select(x => x.Key);
+                WriteRow(writer, keys);
+            }
+
+            var values = records.Select(x => x.Value);
+            WriteObjectRow(writer, values);
+        }
+
+        public static void Write(TextWriter writer, IEnumerable<KeyValuePair<string, string>> records)
+        {
+            if (records == null) return; //AOT
+
+            var requireHeaders = !CsvConfig<IEnumerable<KeyValuePair<string, string>>>.OmitHeaders;
+            if (requireHeaders)
+            {
+                var keys = records.Select(x => x.Key);
+                WriteRow(writer, keys);
+            }
+
+            var values = records.Select(x => x.Value);
+            WriteObjectRow(writer, values);
+        }
+
         public static void Write(TextWriter writer, IEnumerable<IDictionary<string, object>> records) 
         {
             if (records == null) return; //AOT
@@ -230,12 +260,6 @@ public static void Write(TextWriter writer, IEnumerable<T> records)
                 return;
             }
 
-            if (typeof(T) == typeof(Dictionary<string, object>) || typeof(T) == typeof(IDictionary<string, object>))
-            {
-                CsvDictionaryWriter.Write(writer, (IEnumerable<IDictionary<string, object>>)records);
-                return;
-            }
-
             if (typeof(T).IsAssignableFromType(typeof(Dictionary<string, object>))) //also does `object`
             {
                 var dynamicList = records.Select(x => x.ToObjectDictionary()).ToList();
@@ -292,7 +316,18 @@ public static void WriteRow(TextWriter writer, T row)
         {
             if (writer == null) return; //AOT
 
-            Write(writer, new[] { row });
+            if (row is IEnumerable<KeyValuePair<string, object>> kvps)
+            {
+                CsvDictionaryWriter.Write(writer, kvps);
+            }
+            else if (row is IEnumerable<KeyValuePair<string, string>> kvpStrings)
+            {
+                CsvDictionaryWriter.Write(writer, kvpStrings);
+            }
+            else
+            {
+                Write(writer, new[] { row });
+            }
         }
 
         public static void WriteRow(TextWriter writer, IEnumerable<string> row)

src/ServiceStack.Text/StringExtensions.cs

@@ -1207,7 +1207,7 @@ public static int CountOccurrencesOf(this string text, char needle)
 
         public static string NormalizeNewLines(this string text)
         {
-            return text?.Replace("\r\n", "\n");
+            return text?.Replace("\r\n", "\n").Trim();
         }
 
 #if !LITE

tests/ServiceStack.Text.Tests/CsvSerializerTests.cs

@@ -275,6 +275,86 @@ public void Can_Serialize_using_custom_CSV_ItemString()
             CsvConfig.Reset();
         }
 
+        [Test]
+        public void Can_serialize_ObjectDictionary_list()
+        {
+            var rows = new List<Dictionary<string, object>>
+            {
+                new Dictionary<string, object>
+                {
+                    { "Id", 1 },
+                    { "CustomerId", "ALFKI" },
+                },
+                new Dictionary<string, object>
+                {
+                    { "Id", 2 },
+                    { "CustomerId", "ANATR" },
+                },
+            };
+
+            Assert.That(rows.ToCsv().NormalizeNewLines(), Is.EqualTo("Id,CustomerId\n1,ALFKI\n2,ANATR").Or.EqualTo("CustomerId,Id\nALFKI,1\nANATR,2"));
+        }
+
+        [Test]
+        public void Can_serialize_StringDictionary_list()
+        {
+            var rows = new List<Dictionary<string, string>>
+            {
+                new Dictionary<string, string>
+                {
+                    { "Id", "1" },
+                    { "CustomerId", "ALFKI" },
+                },
+                new Dictionary<string, string>
+                {
+                    { "Id", "2" },
+                    { "CustomerId", "ANATR" },
+                },
+            };
+
+            Assert.That(rows.ToCsv().NormalizeNewLines(), Is.EqualTo("Id,CustomerId\n1,ALFKI\n2,ANATR").Or.EqualTo("CustomerId,Id\nALFKI,1\nANATR,2"));
+        }
+
+        [Test]
+        public void Can_serialize_single_ObjectDictionary_or_ObjectKvps()
+        {
+            var row = new Dictionary<string, object>
+            {
+                { "Id", 1 },
+                { "CustomerId", "ALFKI" },
+            };
+
+            Assert.That(row.ToCsv().NormalizeNewLines(), Is.EqualTo("Id,CustomerId\n1,ALFKI").Or.EqualTo("CustomerId,Id\nALFKI,1"));
+
+            var kvps = new[]
+            {
+                new KeyValuePair<string, object>("Id", 1),
+                new KeyValuePair<string, object>("CustomerId", "ALFKI"),
+            };
+
+            Assert.That(kvps.ToCsv().NormalizeNewLines(), Is.EqualTo("Id,CustomerId\n1,ALFKI").Or.EqualTo("CustomerId,Id\nALFKI,1"));
+        }
+
+        [Test]
+        public void Can_serialize_single_StringDictionary_or_StringKvps()
+        {
+            var row = new Dictionary<string, string>
+            {
+                { "Id", "1" },
+                { "CustomerId", "ALFKI" },
+            };
+
+            Assert.That(row.ToCsv().NormalizeNewLines(), Is.EqualTo("Id,CustomerId\n1,ALFKI").Or.EqualTo("CustomerId,Id\nALFKI,1"));
+
+            var kvps = new[]
+            {
+                new KeyValuePair<string, string>("Id", "1"),
+                new KeyValuePair<string, string>("CustomerId", "ALFKI"),
+            };
+
+            Assert.That(kvps.ToCsv().NormalizeNewLines(), Is.EqualTo("Id,CustomerId\n1,ALFKI").Or.EqualTo("CustomerId,Id\nALFKI,1"));
+        }
+
         [Test]
         public void serialize_Category()
         {

tests/ServiceStack.Text.Tests/DynamicJsonTests.cs

@@ -15,7 +15,7 @@ public void Can_Serialize_dynamic_collection()
             Assert.That(json, Is.EqualTo("[{\"Name\":\"Foo\"},{\"Name\":\"Bar\"}]"));
 
             string csv = CsvSerializer.SerializeToString(rows);
-            Assert.That(csv.NormalizeNewLines(), Is.EqualTo("Name\nFoo\nBar\n"));
+            Assert.That(csv.NormalizeNewLines(), Is.EqualTo("Name\nFoo\nBar"));
         }
 
         [Test]