How to export DeepCTR model to onnx ?

Please refer to the FAQ in doc and search for the related issues before you ask the question.

Describe the question(问题描述)
I would like to export model to onnx format, so I can use it for example with Apache PredictionIO

Additional context
I tried with :

    dummy_input = np.array([np.array([[0]]), np.array([[0]])])
    pred_ans = model.predict(dummy_input, 100)
    print(pred_ans)
    torch.onnx.export(model, (dummy_input), "deepCTR.onnx")

predict works well, I am getting: [[0.0065056]]
but wwith onnx.export, I am getting error with this trace:

RuntimeError: Only tuples, lists and Variables supported as JIT inputs/outputs. Dictionaries and strings are also accepted but their usage is not recommended. But got unsupported type numpy.ndarray

Operating environment(运行环境):

• python version: 3.7
• torch version: 1.4.0
• deepctr-torch version: 0.1.0

Review the FAQ and related issues first, then reproduce the failure from the provided model.predict and torch.onnx.export calls using the stated Python 3.7, PyTorch 1.4.0, and deepctr-torch 0.1.0 versions. Done means the DeepCTR model can be exported to ONNX for use with Apache PredictionIO, with the supported input form and limitations documented.