ML.NET: How to save model to a database? - ml.net

Question

I run a ML.NET sample app , there is the code in the Program.cs :
…
Console.WriteLine(“Training model…”);
var model = pipeline.Fit(trainTestData.TrainSet);
…
i.e. every time the model trained and created.
The question: Is it possible to save the model in a database after it once trained and created and then load and reuse the saved one?
It can be saved to zip file and loaded and reused. But how to save/load it to database?

Answer 1

The model can be saved to a MemoryStream, then converted to a byte array and stored in the database.
using var memoryStream = new MemoryStream();
_mlContext.Model.Save(trainedModel, trainData.Schema, memoryStream);
_dbContext.Models.Add(new Model
{
Data = stream.ToArray()
// ...metadata
});
Save (stream overload signature):
// Summary:
// Save a transformer model and the loader used to create its input data to the
// stream.
//
// Parameters:
// model:
// The trained model to be saved. Note that this can be null, as a shorthand for
// an empty transformer chain. Upon loading with Microsoft.ML.ModelOperationsCatalog.LoadWithDataLoader(System.IO.Stream,Microsoft.ML.IDataLoader{Microsoft.ML.Data.IMultiStreamSource}#)
// the returned value will be an empty Microsoft.ML.Data.TransformerChain`1.
//
// loader:
// The loader that was used to create data to train the model.
//
// stream:
// A writeable, seekable stream to save to.
public void Save<TSource>(ITransformer model, IDataLoader<TSource> loader, Stream stream)