(l-serialization)=

Serialization

Save a model and any Proto class

This ONNX graph needs to be serialized into one contiguous memory buffer. Method SerializeToString is available in every ONNX objects.

with open("model.onnx", "wb") as f:
    f.write(onnx_model.SerializeToString())

This method has the following signature.

{eval-rst}

.. autoclass:: onnx.ModelProto
    :members: SerializeToString

Every Proto class implements method SerializeToString. Therefore the following code works with any class described in page {ref}l-onnx-classes.

with open("proto.pb", "wb") as f:
    f.write(proto.SerializeToString())

Next example shows how to save a {ref}l-nodeproto.

{eval-rst}

.. exec_code::

    from onnx import NodeProto

    node = NodeProto()
    node.name = "example-type-proto"
    node.op_type = "Add"
    node.input.extend(["X", "Y"])
    node.output.extend(["Z"])

    with open("node.pb", "wb") as f:
        f.write(node.SerializeToString())

Load a model

Following function only automates the loading of a class {ref}l-modelproto. Next sections shows how to restore any other proto class.

{eval-rst}

.. autofunction:: onnx.load

from onnx import load

onnx_model = load("model.onnx")

Or:

from onnx import load

with open("model.onnx", "rb") as f:
    onnx_model = load(f)

Next function does the same from a bytes array.

{eval-rst}

.. autofunction:: onnx.load_model_from_string

(l-onnx-load-data)=

Load a Proto

Proto means here any type containing data including a model, a tensor, a sparse tensor, any class listed in page {ref}l-onnx-classes. The user must know the type of the data he needs to restore and then call method ParseFromString. protobuf does not store any information about the class of the saved data. Therefore, this class must be known before restoring an object.

{eval-rst}

.. autoclass:: onnx.ModelProto
    :members: ParseFromString

Next example shows how to restore a {ref}l-nodeproto.

{eval-rst}

.. exec_code::

    from onnx import NodeProto

    tp2 = NodeProto()
    with open("node.pb", "rb") as f:
        content = f.read()

    tp2.ParseFromString(content)

    print(tp2)

A shortcut exists for {ref}l-tensorproto:

{eval-rst}

.. autofunction:: onnx.load_tensor_from_string