The simplest "select a row from a table" implementation I could come up with

[llimllib]

I wanted to allow a user to pick an option from a list using rich, and not needing support for the windows command line.

Textual/click/etc seemed pretty heavy, and I wanted to know how this would work, so I wanted to not add any dependencies.

Here's the simplest implementation I could come up with; I welcome feedback on how to make it simpler or better, but I'm putting it here mainly for anybody else to see how they might begin:

Screen.Recording.2021-12-28.at.12.48.24.PM.mov

(update: see comment below for a much improved version)

menutest.py:

from datetime import datetime
import os

import rich.box
from rich.console import Console
from rich.style import Style
from rich.table import Table
from getchar import getchar

SELECTED = Style(color="blue", bgcolor="white", bold=True)


def print_table(console, table, rows=[], selected=0):
    for i, row in enumerate(rows):
        if i == selected:
            table.add_row(*row, style=SELECTED)
        else:
            table.add_row(*row)

    console.print(table)


def make_table(headers):
    table = Table(box=rich.box.MINIMAL)
    for i in range(len(headers)):
        table.add_column(headers[i])

    return table


UP = "\x1b[A"
DOWN = "\x1b[B"
ENTER = "\r"

selected = 0
console = Console()


def format_ts(ts):
    return datetime.utcfromtimestamp(ts).strftime("%Y-%m-%d")


# get the first 5 items from os.listdir to show in the table
headers = ["filename", "size (bytes)", "modified"]
items = [
    (fname, str(stat.st_size), format_ts(stat.st_mtime))
    for fname, stat in [(f, os.stat(f)) for f in os.listdir()[:5]]
]

console.clear()
print_table(console, make_table(headers), items, selected)

while True:
    ch = getchar(False)
    if ch == UP:
        selected = max(0, selected - 1)
    if ch == DOWN:
        selected = min(len(items) - 1, selected + 1)
    if ch == ENTER:
        print("you selected: ", items[selected])
        break
    console.clear()
    print_table(console, make_table(headers), items, selected)

getchar.py is a modification of click's input handling code:

# modified from https://github.com/pallets/click/blob/051d57cef4ce59212dc1175ad4550743bf47d840/src/click/_termui_impl.py
import contextlib
import codecs
import os
import sys
import tty
import termios
import typing as t


def _translate_ch_to_exc(ch: str) -> t.Optional[BaseException]:
    if ch == "\x03":
        raise KeyboardInterrupt()

    if ch == "\x04":  # Unix-like, Ctrl+D
        raise EOFError()

    return None


def is_ascii_encoding(encoding: str) -> bool:
    """Checks if a given encoding is ascii."""
    try:
        return codecs.lookup(encoding).name == "ascii"
    except LookupError:
        return False


def get_best_encoding(stream: t.IO) -> str:
    """Returns the default stream encoding if not found."""
    rv = getattr(stream, "encoding", None) or sys.getdefaultencoding()
    if is_ascii_encoding(rv):
        return "utf-8"
    return rv


@contextlib.contextmanager
def raw_terminal() -> t.Iterator[int]:
    f: t.Optional[t.TextIO]
    fd: int

    if not sys.stdin.isatty():
        f = open("/dev/tty")
        fd = f.fileno()
    else:
        fd = sys.stdin.fileno()
        f = None

    try:
        old_settings = termios.tcgetattr(fd)

        try:
            tty.setraw(fd)
            yield fd
        finally:
            termios.tcsetattr(fd, termios.TCSADRAIN, old_settings)
            sys.stdout.flush()

            if f is not None:
                f.close()
    except termios.error:
        pass


# this won't work in windows because I only copied the unix version
def getchar(echo: bool) -> str:
    with raw_terminal() as fd:
        ch = os.read(fd, 32).decode(get_best_encoding(sys.stdin), "replace")

        if echo and sys.stdout.isatty():
            sys.stdout.write(ch)

        _translate_ch_to_exc(ch)
        return ch


if __name__ == "__main__":
    import json

    while True:
        ch = getchar(False)
        print(json.dumps(ch))
        if ch == "\x1b[A":
            print("up")
        if ch == "\x1b[B":
            print("down")
        if ch == "\x1b[B":
            print("right")
        if ch == "\x1b[D":
            print("left")

[llimllib]

Here's an improved version using a live table:

from datetime import datetime
import os

from rich import box
from rich.live import Live
from rich.table import Table
from rich.style import Style

from getchar import getchar

SELECTED = Style(color="blue", bgcolor="white", bold=True)
UP = "\x1b[A"
DOWN = "\x1b[B"
ENTER = "\r"


def generate_table(headers, rows, selected) -> Table:
    table = Table(box=box.MINIMAL)

    for h in headers:
        table.add_column(h)

    for i, row in enumerate(rows):
        table.add_row(*row, style=SELECTED if i == selected else None)

    return table


def format_ts(ts):
    return datetime.utcfromtimestamp(ts).strftime("%Y-%m-%d")


# get the first 10 items from os.listdir to show in the table
headers = ["filename", "size (bytes)", "modified"]
items = [
    (fname, str(stat.st_size), format_ts(stat.st_mtime))
    for fname, stat in [(f, os.stat(f)) for f in os.listdir()[:5]]
][:10]

selected = 0
with Live(generate_table(headers, items, selected), auto_refresh=False) as live:
    while True:
        ch = getchar(False)
        if ch == UP:
            selected = max(0, selected - 1)
        elif ch == DOWN:
            selected = min(len(items) - 1, selected + 1)
        elif ch == ENTER:
            live.stop()
            print("you selected: ", items[selected])
            break
        live.update(generate_table(headers, items, selected), refresh=True)

One thing to note is that it doesn't handle the table being larger than the available vertical screen space.

[llimllib]

And, finally a version that uses readchar (pip install readchar) and handles the case where the list has more rows than available in the console:

from datetime import datetime
import os

from rich.console import Console
from rich.live import Live
from rich.table import Table
from rich.style import Style
from rich import box

# pip install readchar
# https://github.com/magmax/python-readchar seems low-overhead and simple
from readchar import readkey, key

SELECTED = Style(color="blue", bgcolor="white", bold=True)


def generate_table(console, headers, rows, selected) -> Table:
    table = Table(box=box.MINIMAL)

    for h in headers:
        table.add_column(h)

    size = console.height - 4
    if len(rows) + 3 > size:
        if selected < size / 2:
            rows = rows[:size]
        elif selected + size / 2 > len(items):
            rows = rows[-size:]
            selected -= len(items) - size
        else:
            rows = rows[selected - size // 2 : selected + size // 2]
            selected -= selected - size // 2

    for i, row in enumerate(rows):
        table.add_row(*row, style=SELECTED if i == selected else None)

    return table


def format_ts(ts):
    return datetime.utcfromtimestamp(ts).strftime("%Y-%m-%d")


headers = ["filename", "size (bytes)", "modified"]
items = [
    (fname, str(stat.st_size), format_ts(stat.st_mtime))
    for fname, stat in [(f, os.stat(f)) for f in os.listdir()]
]

console = Console()
selected = 0
with Live(
    generate_table(console, headers, items, selected), auto_refresh=False
) as live:
    while True:
        ch = readkey()
        if ch == key.UP or ch == "k":
            selected = max(0, selected - 1)
        if ch == key.DOWN or ch == "j":
            selected = min(len(items) - 1, selected + 1)
        if ch == key.ENTER:
            live.stop()
            print("you selected: ", items[selected])
            break
        live.update(generate_table(console, headers, items, selected), refresh=True)

[WeebMogul]

Learning about the Rich library and wanted to make a scrollable table for a task tracker type object. This was very helpful.

[amoksito]

Excellent!

[llimllib]

Updated for newer python, and to gracefully handle ctrl-c

from datetime import datetime, UTC
import os
import sys
from os import path
import signal

from rich.console import Console
from rich.live import Live
from rich.table import Table
from rich.style import Style
from rich import box

# pip install readchar
# https://github.com/magmax/python-readchar seems low-overhead and simple
from readchar import readkey, key

SELECTED = Style(color="blue", bgcolor="white", bold=True)

# if ctrl-c, quit gracefully
signal.signal(signal.SIGINT, lambda _, __: sys.exit(0))


def generate_table(console, headers, rows, selected) -> Table:
    table = Table(box=box.MINIMAL)

    for h in headers:
        table.add_column(h)

    size = console.height - 4
    if len(rows) + 3 > size:
        if selected < size / 2:
            rows = rows[:size]
        elif selected + size / 2 > len(items):
            rows = rows[-size:]
            selected -= len(items) - size
        else:
            rows = rows[selected - size // 2 : selected + size // 2]
            selected -= selected - size // 2

    for i, row in enumerate(rows):
        table.add_row(*row, style=SELECTED if i == selected else None)

    return table


def format_ts(ts):
    return datetime.fromtimestamp(ts, UTC).strftime("%Y-%m-%d")


headers = ["filename", "size (bytes)", "modified"]
dir = sys.argv[1] if len(sys.argv) > 1 else "."
items = sorted(
    (fname, str(stat.st_size), format_ts(stat.st_mtime))
    for fname, stat in [(f, os.stat(path.join(dir, f))) for f in os.listdir(dir)]
)

console = Console()
selected = 0
with Live(
    generate_table(console, headers, items, selected), auto_refresh=False
) as live:
    while ch := readkey():
        if ch == key.UP or ch == "k":
            selected = max(0, selected - 1)
        if ch == key.DOWN or ch == "j":
            selected = min(len(items) - 1, selected + 1)
        if ch == key.ENTER:
            live.stop()
            print("you selected: ", items[selected])
            break
        live.update(generate_table(console, headers, items, selected), refresh=True)