Append list to appender

Author: Giorgi

DuckDB.NET.Bindings/DuckDBNativeObjects.cs

@@ -159,10 +159,10 @@ public void Dispose()
 }
 
 [StructLayout(LayoutKind.Sequential)]
-public readonly struct DuckDBListEntry
+public struct DuckDBListEntry(ulong offset, ulong length)
 {
-    public ulong Offset { get; }
-    public ulong Length { get; }
+    public ulong Offset { get; private set; } = offset;
+    public ulong Length { get; private set; } = length;
 }
 
 public struct DuckDBString

DuckDB.NET.Data/DuckDBAppenderRow.cs

@@ -1,6 +1,7 @@
 using DuckDB.NET.Data.Internal.Writer;
 using DuckDB.NET.Native;
 using System;
+using System.Collections.Generic;
 using System.Numerics;
 
 namespace DuckDB.NET.Data;
@@ -101,6 +102,12 @@ public DuckDBAppenderRow AppendValue(TimeSpan? value)
 
     #endregion
 
+    #region Composite Types
+
+    public DuckDBAppenderRow AppendValue<T>(IReadOnlyCollection<T>? value) => AppendCollectionValue(value);
+
+    #endregion
+
     private DuckDBAppenderRow AppendValueInternal<T>(T? value)
     {
         CheckColumnAccess();
@@ -112,6 +119,17 @@ private DuckDBAppenderRow AppendValueInternal<T>(T? value)
         return this;
     }
 
+    private DuckDBAppenderRow AppendCollectionValue<T>(IReadOnlyCollection<T>? value)
+    {
+        CheckColumnAccess();
+
+        vectorWriters[columnIndex].AppendCollection(value, rowIndex);
+
+        columnIndex++;
+
+        return this;
+    }
+
 #if NET6_0_OR_GREATER
     private unsafe DuckDBAppenderRow AppendSpan(Span<byte> val)
     {

DuckDB.NET.Data/Internal/Writer/ListVectorDataWriter.cs

@@ -0,0 +1,36 @@
+using System;
+using System.Collections.Generic;
+using DuckDB.NET.Native;
+
+namespace DuckDB.NET.Data.Internal.Writer;
+
+internal sealed unsafe class ListVectorDataWriter : VectorDataWriterBase
+{
+    private ulong offset = 0;
+    private readonly VectorDataWriterBase listDataWriter;
+
+    public ListVectorDataWriter(IntPtr vector, void* vectorData, DuckDBType columnType, DuckDBLogicalType logicalType) : base(vector, vectorData, columnType)
+    {
+        using var childType = NativeMethods.LogicalType.DuckDBListTypeChildType(logicalType);
+        var childVector = NativeMethods.Vectors.DuckDBListVectorGetChild(vector);
+        listDataWriter = VectorDataWriterFactory.CreateWriter(childVector, childType);
+    }
+
+    internal override bool AppendCollection<T>(IReadOnlyCollection<T>? value, int rowIndex)
+    {
+        if (value == null)
+        {
+            AppendNull(rowIndex);
+            return true;
+        }
+
+        var index = 0;
+
+        foreach (var item in value)
+        {
+            listDataWriter.AppendValue(item, index++);
+        }
+
+        return AppendValueInternal(new DuckDBListEntry(offset, (ulong)value.Count), rowIndex);
+    }
+}

DuckDB.NET.Data/Internal/Writer/VectorDataWriterBase.cs

@@ -1,4 +1,6 @@
 using System;
+using System.Collections;
+using System.Collections.Generic;
 using System.Numerics;
 using DuckDB.NET.Native;
 
@@ -93,6 +95,8 @@ public unsafe void AppendValue<T>(T value, int rowIndex)
 
     internal virtual bool AppendBigInteger(BigInteger value, int rowIndex) => ThrowException<BigInteger>();
 
+    internal virtual bool AppendCollection<T>(IReadOnlyCollection<T>? value, int rowIndex) => ThrowException<bool>();
+
     private bool ThrowException<T>()
     {
         throw new InvalidOperationException($"Cannot write {typeof(T).Name} to {columnType} column");

DuckDB.NET.Data/Internal/Writer/VectorDataWriterFactory.cs

@@ -22,7 +22,7 @@ public static unsafe VectorDataWriterBase CreateWriter(IntPtr vector, DuckDBLogi
             DuckDBType.Boolean => new BooleanVectorDataWriter(vector, dataPointer, columnType),
 
             DuckDBType.Map => throw new NotImplementedException($"Writing {columnType} to data chunk is not yet supported"),
-            DuckDBType.List => throw new NotImplementedException($"Writing {columnType} to data chunk is not yet supported"),
+            DuckDBType.List => new ListVectorDataWriter(vector, dataPointer, columnType, logicalType),
             DuckDBType.Array => throw new NotImplementedException($"Writing {columnType} to data chunk is not yet supported"),
             DuckDBType.Blob => new StringVectorDataWriter(vector, dataPointer, columnType),
             DuckDBType.Varchar => new StringVectorDataWriter(vector, dataPointer, columnType),

DuckDB.NET.Test/ManagedAppenderTests.cs

@@ -268,6 +268,38 @@ public void TemporalValues()
         result.Select(tuple => tuple.Item8).Should().BeEquivalentTo(dates.Select(TimeOnly.FromDateTime));
     }
 
+    [Fact]
+    public void ListValues()
+    {
+        Command.CommandText = "CREATE TABLE managedAppenderLists(a INTEGER, b INTEGER[]" +
+                              //", c INTEGER[][]" +
+                              ");";
+        Command.ExecuteNonQuery();
+
+        var rows = 20;
+        using (var appender = Connection.CreateAppender("managedAppenderLists"))
+        {
+            for (int i = 0; i < rows; i++)
+            {
+                appender.CreateRow()
+                    .AppendValue(i)
+                    .AppendValue(Enumerable.Range(0, i).ToList())
+                    //.AppendValue(new List<List<int>>{ Enumerable.Range(0, 5).ToList() })
+                    .EndRow();
+            }
+        }
+
+        Command.CommandText = "SELECT * FROM managedAppenderLists order by 1";
+        var reader = Command.ExecuteReader();
+
+        int index = 0;
+        while (reader.Read())
+        {
+            var ints = reader.GetFieldValue<List<int>>(1);
+            ints.Should().BeEquivalentTo(Enumerable.Range(0, index++).ToList());
+        }
+    }
+
     [Fact]
     public void IncompleteRowThrowsException()
     {