Issue #75 Add Section in README

Author: bytefish

README.md

@@ -137,6 +137,101 @@ For example:
 .Map("geo", x => x.geo, NpgsqlDbType.Point)
 ```
 
+## Mapping Composite Types ##
+
+Imagine you have a composite type called ``person_type`` in a schema of your database:
+
+```sql
+create type sample.person_type as
+(
+    first_name text,
+    last_name text,
+    birth_date date
+);
+```
+
+And it is used in a table called ``CompositeTest``:
+
+```sql
+create table sample.CompositeTest
+(
+    col_text text,
+    col_person sample.person_type                
+)
+```
+
+You first need to map the Postgres ``person_type`` to a C\# class:
+
+```csharp
+private class PersonType
+{
+    public string FirstName { get; set; }
+
+    public string LastName { get; set; }
+
+    public DateTime BirthDate { get; set; }
+}
+```
+
+A hint: Npgsql always converts the property name to a snake case column name, so ``FirstName`` is mapped 
+to ``first_name`` by convention. You can use the ``[PgName]`` attribute to explicitly set the Postgres type 
+name.
+
+Next the table is mapped to the following C\# model:
+
+```csharp
+private class SampleEntity
+{
+    public string TextColumn { get; set; }
+
+    public PersonType CompositeTypeColumn { get; set; }
+}
+```
+
+And now we can bulk write ``SampleEntity`` instances using PostgreSQLCopyHelper like this:
+
+```csharp
+connection.TypeMapper.MapComposite<PersonType>("sample.person_type");
+
+// ... alternatively you can set it globally at any place in your application using the NpgsqlConnection.GlobalTypeMapper:
+//
+// NpgsqlConnection.GlobalTypeMapper.MapComposite<PersonType>("sample.person_type");
+
+var subject = new PostgreSQLCopyHelper<SampleEntity>("sample", "CompositeTest")
+         .MapText("col_text", x => x.TextColumn)
+         .Map("col_person", x => x.CompositeTypeColumn);
+
+var entities = new List<SampleEntity>();
+
+entities.Add(new SampleEntity
+{
+    TextColumn = "0",
+    CompositeTypeColumn = new PersonType { FirstName = "Fake", LastName = "Fakerton", BirthDate = new DateTime(1987, 1, 11) }
+});
+
+entities.Add(new SampleEntity
+{
+    TextColumn = "1",
+    CompositeTypeColumn = new PersonType { FirstName = "Philipp", LastName = "Wagner", BirthDate = new DateTime(1912, 1, 11) }
+});
+
+subject.SaveAll(connection, entities);
+
+```
+
+In the listing you see, that we need to tell Npgsql how to map the Postgres type using ``MapComposite<>``. This can 
+be done per Connection like this:
+
+```
+connection.TypeMapper.MapComposite<PersonType>("sample.person_type");
+```
+
+Or you can alternatively set the Mapping globally at any place in your application using the ``NpgsqlConnection.GlobalTypeMapper``:
+
+```
+NpgsqlConnection.GlobalTypeMapper.MapComposite<PersonType>("sample.person_type");
+```
+
 ## PostgreSQLCopyHelper.NodaTime: NodaTime Support ##
 
 The [PostgreSQLCopyHelper.NodaTime](https://www.nuget.org/packages/PostgreSQLCopyHelper.NodaTime/) package extends PostgreSQLCopyHelper for [NodaTime](https://nodatime.org/) types. 

artifacts/PostgreSQLCopyHelper.2.8.0.nupkg

@@ -29,5 +29,27 @@ public static IList<object[]> GetAll(this NpgsqlConnection connection, string sc
 
             return result;
         }
+
+        public static IList<object[]> GetAll(this NpgsqlConnection connection, string sqlStatement)
+        {
+            var sqlCommand = new NpgsqlCommand(sqlStatement, connection);
+
+            var result = new List<object[]>();
+            using (var dataReader = sqlCommand.ExecuteReader())
+            {
+                while (dataReader.Read())
+                {
+                    var values = new object[dataReader.FieldCount];
+                    for (var i = 0; i < dataReader.FieldCount; i++)
+                    {
+                        values[i] = dataReader[i];
+                    }
+                    result.Add(values);
+                }
+            }
+
+            return result;
+        }
+
     }
 }

artifacts/PostgreSQLCopyHelper.2.8.0.symbols.nupkg

@@ -13,19 +13,23 @@ namespace PostgreSQLCopyHelper.Test.Issues
     [TestFixture]
     public class Issue75_CompositeTypes_Test : TransactionalTestBase
     {
+        private class SampleEntity
+        {
+            public string TextColumn { get; set; }
+
+            public PersonType CompositeTypeColumn { get; set; }
+        }
+
         private class PersonType
         {
-            [PgName("first_name")]
             public string FirstName { get; set; }
 
-            [PgName("last_name")]
             public string LastName { get; set; }
 
-            [PgName("birth_date")]
             public DateTime BirthDate { get; set; }
         }
 
-        private PostgreSQLCopyHelper<PersonType> subject;
+        private PostgreSQLCopyHelper<SampleEntity> subject;
 
         protected override void OnSetupInTransaction()
         {
@@ -45,31 +49,49 @@ public void Test_CompositeBulkInsert()
 
             connection.TypeMapper.MapComposite<PersonType>("sample.person_type");
 
-            subject = new PostgreSQLCopyHelper<PersonType>("sample", "CompositeTest")
-                     .Map("col_person", x => x);
+            // ... alternatively you can set it globally at any place in your application using the NpgsqlConnection.GlobalTypeMapper:
+            //
+            // NpgsqlConnection.GlobalTypeMapper.MapComposite<PersonType>("sample.person_type");
 
-            var entities = new List<PersonType>();
+            subject = new PostgreSQLCopyHelper<SampleEntity>("sample", "CompositeTest")
+                     .MapText("col_text", x => x.TextColumn)
+                     .Map("col_person", x => x.CompositeTypeColumn);
 
-            entities.Add(new PersonType { FirstName = "Philipp", LastName = "Wagner", BirthDate = new DateTime(1912, 1, 11) });
-            entities.Add(new PersonType { FirstName = "Fake", LastName = "Fakerton", BirthDate = new DateTime(1987, 1, 11) });
+            var entities = new List<SampleEntity>();
+
+            entities.Add(new SampleEntity
+            {
+                TextColumn = "0",
+                CompositeTypeColumn = new PersonType { FirstName = "Fake", LastName = "Fakerton", BirthDate = new DateTime(1987, 1, 11) }
+            });
+    
+            entities.Add(new SampleEntity
+            {
+                TextColumn = "1",
+                CompositeTypeColumn = new PersonType { FirstName = "Philipp", LastName = "Wagner", BirthDate = new DateTime(1912, 1, 11) }
+            });
 
-            // Try to work with the Bulk Inserter:
             subject.SaveAll(connection, entities);
 
-            var result = connection.GetAll("sample", "CompositeTest")
-                .Select(x => (PersonType) x[0])
-                .OrderBy(x => x.FirstName)
+            var result = connection.GetAll("SELECT col_text, col_person from sample.CompositeTest")
+                .Select(x => new SampleEntity {
+                    TextColumn = (string) x[0],
+                    CompositeTypeColumn = (PersonType) x[1]
+                })
+                .OrderBy(x => x.TextColumn)
                 .ToList();
 
             Assert.AreEqual(2, result.Count);
 
-            Assert.AreEqual("Fake", result[0].FirstName);
-            Assert.AreEqual("Fakerton", result[0].LastName);
-            Assert.AreEqual(new DateTime(1987, 1, 11), result[0].BirthDate);
+            Assert.AreEqual("0", result[0].TextColumn);
+            Assert.AreEqual("Fake", result[0].CompositeTypeColumn.FirstName);
+            Assert.AreEqual("Fakerton", result[0].CompositeTypeColumn.LastName);
+            Assert.AreEqual(new DateTime(1987, 1, 11), result[0].CompositeTypeColumn.BirthDate);
 
-            Assert.AreEqual("Philipp", result[1].FirstName);
-            Assert.AreEqual("Wagner", result[1].LastName);
-            Assert.AreEqual(new DateTime(1912, 1, 11), result[1].BirthDate);
+            Assert.AreEqual("1", result[1].TextColumn);
+            Assert.AreEqual("Philipp", result[1].CompositeTypeColumn.FirstName);
+            Assert.AreEqual("Wagner", result[1].CompositeTypeColumn.LastName);
+            Assert.AreEqual(new DateTime(1912, 1, 11), result[1].CompositeTypeColumn.BirthDate);
         }
 
         private void CreateTableAndType()
@@ -89,6 +111,7 @@ birth_date date
             {
                 var sqlStatement = @"CREATE TABLE sample.CompositeTest
                                 (
+                                    col_text text,
                                     col_person sample.person_type                
                                  );";
 
@@ -112,7 +135,6 @@ private void DropTableAndType()
 
                 sqlCommand.ExecuteNonQuery();
             }
-
         }
     }
 }