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Return byte arrays from typed BLOB reads #384

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Merged
Giorgi merged 2 commits into from
Oct 26, 2026
Merged

Return byte arrays from typed BLOB reads #384

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32cc4a7
Fix typed BLOB reads as byte arrays
alaricd Oct 26, 2026
ed1afff
Fix composite BLOB reads as byte arrays
alaricd Oct 26, 2026
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12 changes: 10 additions & 2 deletions DuckDB.NET.Data/DataChunk/Reader/StringVectorDataReader.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -20,7 +20,9 @@ protected override T GetValidValue<T>(ulong offset)
return DuckDBType switch
{
DuckDBType.Bit => GetBitString<T>(offset),
DuckDBType.Blob => (T)(object)GetStream(offset),
DuckDBType.Blob => typeof(T) == typeof(byte[])
? (T)(object)GetBytes(offset)
: (T)(object)GetStream(offset),
DuckDBType.Varchar => (T)(object)GetString(offset),
_ => base.GetValidValue<T>(offset)
};
Expand All @@ -31,7 +33,7 @@ internal override object GetValue(ulong offset, Type targetType)
return DuckDBType switch
{
DuckDBType.Bit => GetBitString(offset),
DuckDBType.Blob => GetStream(offset),
DuckDBType.Blob => targetType == typeof(byte[]) ? GetBytes(offset) : GetStream(offset),
DuckDBType.Varchar => GetString(offset),
_ => base.GetValue(offset, targetType)
};
Expand Down Expand Up @@ -219,4 +221,10 @@ private unsafe Stream GetStream(ulong offset)

return new UnmanagedMemoryStream((byte*)data->Data, data->Length, data->Length, FileAccess.Read);
}

private unsafe byte[] GetBytes(ulong offset)
{
var data = (DuckDBString*)DataPointer + offset;
return new ReadOnlySpan<byte>((void*)data->Data, checked((int)data->Length)).ToArray();
}
}
63 changes: 62 additions & 1 deletion DuckDB.NET.Test/Parameters/BlobParameterTests.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -54,6 +54,62 @@ public void SimpleTest()
reader.GetFieldType(0).Should().Be(typeof(Stream));
}

[Fact]
public void GetFieldValueByteArrayReadsBlob()
{
Command.CommandText = "SELECT '\\x01\\x02\\x03\\x04'::BLOB;";

using var reader = Command.ExecuteReader();
reader.Read().Should().BeTrue();

reader.GetFieldValue<byte[]>(0).Should().Equal(1, 2, 3, 4);
reader.GetValue(0).Should().BeOfType<UnmanagedMemoryStream>();
}

[Fact]
public void GetFieldValueByteArrayReadsEmptyBlob()
{
Command.CommandText = "SELECT ''::BLOB;";

using var reader = Command.ExecuteReader();
reader.Read().Should().BeTrue();

reader.GetFieldValue<byte[]>(0).Should().BeEmpty();
}

[Fact]
public void GetFieldValueByteArrayReadsBlobInAStruct()
{
Command.CommandText = "SELECT {'value': '\\x01\\x02\\x03'::BLOB};";

using var reader = Command.ExecuteReader();
reader.Read().Should().BeTrue();

reader.GetFieldValue<BlobStruct>(0).Value.Should().Equal(1, 2, 3);
}

[Fact]
public void GetFieldValueByteArrayReadsBlobInAMap()
{
Command.CommandText = "SELECT MAP {'value': '\\x04\\x05'::BLOB};";

using var reader = Command.ExecuteReader();
reader.Read().Should().BeTrue();

reader.GetFieldValue<Dictionary<string, byte[]>>(0)["value"].Should().Equal(4, 5);
}

[Fact]
public void GetFieldValueByteArrayReadsBlobInAList()
{
Command.CommandText = "SELECT ['\\x06\\x07'::BLOB, '\\x08'::BLOB];";

using var reader = Command.ExecuteReader();
reader.Read().Should().BeTrue();

reader.GetFieldValue<List<byte[]>>(0).Should().BeEquivalentTo(new[] { new byte[] { 6, 7 }, new byte[] { 8 } });
}

[Fact]
public void SeekTest()
{
Expand Down Expand Up @@ -140,4 +196,9 @@ public void BindParameterWithoutTable()

resultBytes.Should().BeEquivalentTo(value);
}
}

private sealed class BlobStruct
{
public byte[] Value { get; set; } = [];
}
}
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