DataTable.get_cell should accept strings as keys

[barisione]

DataTable.get_cell is defined like this:

def get_cell(self, row_key: RowKey, column_key: ColumnKey) -> CellType:
    """[...]"""
    try:
        cell_value = self._data[row_key][column_key]
    [...]

Which means that passing strings as keys actually works (even if mypy doesn't like it) as keys' hashes are identical to the hashes of the strings they wrap.

Being able to use a string key is convenient otherwise code like this is not useful as you need to also save the return value of add_row (which defeats the point of passing a key in):

class MyApp(App):
    _FOOBAR_KEY = "foobar"

    def on_ready(self):
        [...]
        table.add_row("Foo Bar", key=self._FOOBAR_KEY)

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Name	Value
Textual	0.24.1
Rich	13.3.5

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Name	Value
Version	3.10.1
Implementation	CPython
Compiler	Clang 13.0.0 (clang-1300.0.29.30)
Executable	/Users/bari/.pyenv/versions/3.10.1/envs/undo-core-venv3.10/bin/python3.10

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Name	Value
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[guystreeter]

Other functions like update_cell() accept a str for both row_key and column_key. It seems like this is an oversight.

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[bb-xops]

hey this doesnt work.

row_key, _ = table.coordinate_to_cell_key(table.cursor_coordinate)
current_value = table.get_cell(row_key, "ID")

its giving me this error. I cannot simply used "ID" for my column, super frustrating. It only accepts memory like this 0x105b70100.

CellDoesNotExist: No cell exists for row_key=<textual.widgets._data_table.RowKey object at 0x105b70100>, column_key='ID'.

I took a look at your github PR here that you closed out.
#2876

But it doesn't have test cases for get_cell

[bb-xops]

row_key, col_key = table.coordinate_to_cell_key([table.cursor_row, 0])
current_value = table.get_cell(row_key, col_key)

this was my workaround to get this to work.

[TomJGooding]

@bb-xops I think the problem in your example is that you are mistaking the column key for the column label. See: https://textual.textualize.io/widgets/data_table/#keys

Here's a quick example demonstrating this:

from textual.app import App, ComposeResult
from textual.widgets import DataTable, Footer
from textual.widgets.data_table import CellDoesNotExist


class GetCellApp(App):
    BINDINGS = [
        ("b", "bad_get_cell", "Bad get_cell"),
        ("g", "good_get_cell", "Good get_cell"),
    ]

    def compose(self) -> ComposeResult:
        yield DataTable()
        yield Footer()

    def on_mount(self) -> None:
        table = self.query_one(DataTable)
        table.add_column("ID", key="id-key")
        table.add_column("Name", key="name-key")
        table.add_row(1, "John Smith")

    def action_bad_get_cell(self) -> None:
        table = self.query_one(DataTable)
        row_key, _ = table.coordinate_to_cell_key(table.cursor_coordinate)
        try:
            self.notify(f"{table.get_cell(row_key, 'ID')=}")
        except CellDoesNotExist:
            self.notify(
                "CellDoesNotExist: No cell exists with column key 'ID'",
                severity="error",
            )

    def action_good_get_cell(self) -> None:
        table = self.query_one(DataTable)
        row_key, _ = table.coordinate_to_cell_key(table.cursor_coordinate)
        try:
            self.notify(f"{table.get_cell(row_key, 'id-key')=}")
        except CellDoesNotExist:
            self.notify(
                "CellDoesNotExist: No cell exists with column key 'id-key'",
                severity="error",
            )


if __name__ == "__main__":
    app = GetCellApp()
    app.run()

[bb-xops]

Ah thank you so much. You're correct. I've mistaken Label with the Key.
For anyone else that got lost here let me sum up a tldr on what the issue was.

table.add_column("ID", key="id-key")
row_key, _ = table.coordinate_to_cell_key([table.cursor_coordinate])
table.get_cell(row_key, 'ID') # Incorrect
table.get_cell(row_key, 'id-key') # Correct

Thank you @TomJGooding