[Training] [C# API] There is no way to get input dimensions from onnx model

[peratrepic]

Describe the issue

InferenceSession class provides an API to get input dimensions:

using (InferenceSession inferenceSession = new InferenceSession(TRAINED_MODEL_PATH))
{
    int[] inputDims = inferenceSession.InputMetadata[inferenceSession.InputNames[0]].Dimensions;
}

TrainingSession class provides no such API, nor have I found any other way to load the model using C# ONNX API and read the input dimensions.

To reproduce

Should be clear from issue description, not really much to reproduce, it's just a missing functionality.

Urgency

We are trying to implement on device training scenario and currently we have to send model input dimensions together with onnx model, which seems redundant because that info is already written inside ONNX model, but ONNX C# SDK has no API to extract that info.

ONNX Runtime Installation

Released Package

ONNX Runtime Version or Commit ID

1.16.3

PyTorch Version

2.01

Execution Provider

Default CPU

Execution Provider Library Version

No response

[baijumeswani]

@peratrepic Thanks for opening this issue. We will evaluate if this is something we can easily add to the training API in C# before the upcoming release.

[GeorgeS2019]

Add