JSON import

Labs

This example illustrates importing a SysML v2 model from a JSON file by deserializing it. The main function of interest is json.loads, which takes the JSON text and the URI of the Document the model is deserialized into. That URI does not have to exist on the local file system; it is what relative references inside the JSON are resolved against. The deserialized model can then be used as if it had been loaded from a .sysml file.

Concepts used

• A DeserializedModel is the first of the two values json.loads returns, and its document holds the model that was read from the JSON.

• The syside.json module for reading SysML v2 JSON back into a model.

• walk_ownership_tree is a function that prints out elements in a model in a tree-like format. In this example it is used to show that the model has been successfully deserialized from JSON format.

Example script

import pathlib

import syside

EXAMPLE_DIR = pathlib.Path(__file__).parent
MODEL_FILE_PATH = EXAMPLE_DIR / "example_model_3.sysml"
# The deserialized model will be stored in a document with MODEL_PATH path.
# The MODEL_PATH does not necessarily need to exist on the local file system.
# as_uri() forms a valid file URL from Windows paths too.
MODEL_PATH = MODEL_FILE_PATH.as_uri()

def walk_ownership_tree(element: syside.Element, level: int = 0) -> None:
    """
    Prints out all elements in a model in a tree-like format, where
    child elements appear indented under their parent elements. For
    example:

    Parent
      Child1
      Child2
        Grandchild

    Args:
        element: The model element to start printing from
        level: How many levels to indent (increases for nested elements)
    """
    if element.name is not None:
        print("  " * level, element.name)
    else:
        print("  " * level, "anonymous element")
    # Recursively call walk_ownership_tree() for each owned element
    # (child element).
    element.owned_elements.for_each(
        lambda owned_element: walk_ownership_tree(owned_element, level + 1)
    )

def main() -> None:
    with open(EXAMPLE_DIR / "example_json.json", "r") as f:
        json_import = f.read()
    deserialized_model, _ = syside.json.loads(json_import, MODEL_PATH)

    walk_ownership_tree(deserialized_model.document.root_node)

if __name__ == "__main__":
    main()

Output

 anonymous element
   JSON Export Example
     Electrical
     Mechanical
     Automobile
       Drive Train
       Chassis

Download

Download this example as json_loads.zip.