Javascript Error: IPython is not defined

[giswqs]

I am using the following code to create a new cell programmatically. It works in Jupyter notebook, but I am getting an error Javascript Error: IPython is not defined in JupyteLab. Any advice? Thanks.

def create_code_cell(code='', where='below'):
    """Creates a code cell in the IPython Notebook.

    Args:
        code (str, optional): Code to fill the new code cell with. Defaults to ''.
        where (str, optional): Where to add the new code cell. It can be one of the following: above, below, at_bottom. Defaults to 'below'.
    """

    import base64
    from IPython.display import Javascript, display
    encoded_code = (base64.b64encode(str.encode(code))).decode()
    display(Javascript("""
        var code = IPython.notebook.insert_cell_{0}('code');
        code.set_text(atob("{1}"));
    """.format(where, encoded_code)))

content = 'print("Hello World")'
create_code_cell(code=content)

[jasongrout]

The Javascript interface is completely different in JupyterLab: the IPython global javascript object does not exist.

We do support the payload way of adding a new code cell immediately after the current cell. See https://discourse.jupyter.org/t/how-to-programmatically-add-serveral-new-cells-in-a-notebook-in-jupyterlab/4323

[giswqs]

@jasongrout Thanks for the info. I need to create a new cell programmatically in combination with ipywidgets. The first code block below works without ipywidgets. However, when the function is being called within a ipywidget event, it won't create a new cell. @SylvainCorlay

That JavaScript function I posted earlier works with ipywidgets in Jupyter notebook. I am looking for a solution in JupyterLab.

def create_new_cell(contents, replace=False):

    from IPython.core.getipython import get_ipython
    shell = get_ipython()
    shell.set_next_input(contents, replace=replace)
create_new_cell(contents='print("Hello World!")')

from IPython.display import display
button = widgets.Button(description="Click Me!")
display(button)

def on_button_clicked(b):
    create_new_cell(contents='print("Hello World!")')

button.on_click(on_button_clicked)

[jasongrout]

I think payloads only work with normal cell execute requests, not with the comm messages that ipywidgets uses.

[jasongrout]

I think there is no supported way in JupyterLab to change the notebook cells from python code (e.g., add a cell) other than the deprecated payload option in normal cell execution.

[giswqs]

@jasongrout Thanks for the info. In this case, I will have to use Jupyter notebook.