Context

Suppose one would like two, modular, input boxes in which one can enter a date in format yyyy-mm-dd and optionally the time in format: HH-MM, like:

Please enter the date in format YYYY-MM-DD, (and optionally the time in format HH-MM )`
<highlighed input box when selected>

That:

1. Directly shows a warning/red text (perhaps at the top right of the screen), that says: invalid character entered: "_" if the user tries to type an invalid character, like a.
2. Has a (customizable) shortcut for help, like ctrl+h, which opens a help screen a bit like this example.
3. allows moving to the next box using either the enter button
4. Allows selecting the auto-completed suggestion using the tab button
5. Allows selecting the digits using up and down arrows, and going to the next/previous digit using the left, right arrow, whilst only showing valid options, e.g. if february as month is selected, it only allows selecting 1 to 28/29 (instead of showing 1 to 30/31).
6. Highlights the text box as red if the user selected an invalid date. E.g. selecting 2024-02-29 and then going down on the date one year, e.g. 2023-02-29. (Because 2023 is not a leap year).

Question

How could one build that in urwid?

Attempt

I am experiencing some difficulties in implementing the features 1, 2, 3, 4 and 6 in the MWE below:

import urwid
import datetime
import calendar

class DateTimeEdit(urwid.Edit):
    # ... (the DateTimeEdit class from the previous response) ...
    def __init__(self, caption, date_only=False, **kwargs):
        super().__init__(caption, **kwargs)
        self.date_only = date_only
        self.error_text = urwid.Text("")
        self.help_text = urwid.Text("")
        self.date_parts = [4, 2, 2]  # year, month, day
        self.time_parts = [2, 2]  # hour, minute
        self.current_part = 0
        self.date_values = [None, None, None]
        self.time_values = [None, None]
        self.date_separator = "-"
        self.time_separator = ":"

    def valid_char(self, ch):
        if ch.isdigit() or ch == self.date_separator or (not self.date_only and ch == self.time_separator):
            return True
        else:
            self.error_text.set_text(f"invalid character entered: '{ch}'")
            return False

    def keypress(self, size, key):
        if key == 'ctrl h':
            self.show_help()
            return None
        if key == 'enter':
            return 'enter'  # Signal to move to the next box
        if key == 'tab':
            # Implement suggestion selection here
            return None
        if key == 'left':
            self.move_to_previous_part()
            return None
        if key == 'right':
            self.move_to_next_part()
            return None
        if key == 'up' or key == 'down':
            self.adjust_value(key)
            return None

        result = super().keypress(size, key)
        if result:
            self.error_text.set_text("")  # Clear error on valid input
            self.update_values()
        return result

    def update_values(self):
        text = self.get_edit_text()
        if self.date_only:
            parts = text.split(self.date_separator)
            for i, part in enumerate(parts):
                if part:
                    try:
                        self.date_values[i] = int(part)
                    except ValueError:
                        self.date_values[i] = None
        else:
            date_time_parts = text.split(" ")
            if len(date_time_parts) > 0:
                date_parts = date_time_parts[0].split(self.date_separator)
                for i, part in enumerate(date_parts):
                    if part:
                        try:
                            self.date_values[i] = int(part)
                        except ValueError:
                            self.date_values[i] = None
            if len(date_time_parts) > 1:
                time_parts = date_time_parts[1].split(self.time_separator)
                for i, part in enumerate(time_parts):
                    if part:
                        try:
                            self.time_values[i] = int(part)
                        except ValueError:
                            self.time_values[i] = None

    def move_to_next_part(self):
        if self.date_only:
            if self.current_part < len(self.date_parts) - 1:
                self.current_part += 1
        else:
            if self.current_part < len(self.date_parts) + len(self.time_parts) - 1:
                self.current_part += 1
        self.update_cursor()

    def move_to_previous_part(self):
        if self.current_part > 0:
            self.current_part -= 1
        self.update_cursor()

    def update_cursor(self):
        # Calculate cursor position based on current_part
        cursor_pos = 0
        if self.date_only:
            for i in range(self.current_part):
                cursor_pos += self.date_parts[i] + 1
        else:
            if self.current_part < len(self.date_parts):
                for i in range(self.current_part):
                    cursor_pos += self.date_parts[i] + 1
            else:
                cursor_pos = sum(self.date_parts) + 1
                for i in range(self.current_part - len(self.date_parts)):
                    cursor_pos += self.time_parts[i] + 1
        self.set_edit_pos(cursor_pos)

    def adjust_value(self, direction):
        if self.date_only:
            if self.current_part == 0:
                self.adjust_year(direction)
            elif self.current_part == 1:
                self.adjust_month(direction)
            elif self.current_part == 2:
                self.adjust_day(direction)
        else:
            if self.current_part == 0:
                self.adjust_year(direction)
            elif self.current_part == 1:
                self.adjust_month(direction)
            elif self.current_part == 2:
                self.adjust_day(direction)
            elif self.current_part == 3:
                self.adjust_hour(direction)
            elif self.current_part == 4:
                self.adjust_minute(direction)
        self.update_text()

    def adjust_year(self, direction):
        if self.date_values[0] is None:
            self.date_values[0] = 2024  # Default year
        if direction == 'up':
            self.date_values[0] += 1
        elif direction == 'down':
            self.date_values[0] -= 1

    def adjust_month(self, direction):
        if self.date_values[1] is None:
            self.date_values[1] = 1
        if direction == 'up':
            self.date_values[1] = (self.date_values[1] % 12) + 1
        elif direction == 'down':
            self.date_values[1] = (self.date_values[1] - 2) % 12 + 1

    def adjust_day(self, direction):
        if self.date_values[2] is None:
            self.date_values[2] = 1
        max_days = self.get_max_days()
        if direction == 'up':
            self.date_values[2] = (self.date_values[2] % max_days) + 1
        elif direction == 'down':
            self.date_values[2] = (self.date_values[2] - 2) % max_days + 1

    def adjust_hour(self, direction):
        if self.time_values[0] is None:
            self.time_values[0] = 0
        if direction == 'up':
            self.time_values[0] = (self.time_values[0] + 1) % 24
        elif direction == 'down':
            self.time_values[0] = (self.time_values[0] - 1) % 24

    def adjust_minute(self, direction):
        if self.time_values[1] is None:
            self.time_values[1] = 0
        if direction == 'up':
            self.time_values[1] = (self.time_values[1] + 1) % 60
        elif direction == 'down':
            self.time_values[1] = (self.time_values[1] - 1) % 60

    def get_max_days(self):
        if self.date_values[0] is None or self.date_values[1] is None:
            return 31
        try:
            _, max_days = calendar.monthrange(self.date_values[0], self.date_values[1])
            return max_days
        except ValueError:
            return 31

    def update_text(self):
        date_str = self.date_separator.join(map(lambda x: str(x).zfill(2) if x is not None else "00", self.date_values))
        if self.date_only:
            self.set_edit_text(date_str)
        else:
            time_str = self.time_separator.join(map(lambda x: str(x).zfill(2) if x is not None else "00", self.time_values))
            self.set_edit_text(date_str + " " + time_str)


import urwid
import datetime
import calendar

# (DateTimeEdit class code from previous responses)

def main():
    date_edit = DateTimeEdit("Date (YYYY-MM-DD): ", date_only=True)
    datetime_edit = DateTimeEdit("Date & Time (YYYY-MM-DD HH:MM): ")

    error_display = urwid.Text("")
    date_edit.error_text = error_display
    datetime_edit.error_text = error_display

    pile = urwid.Pile([
        urwid.Text("Enter Date and/or Time:"),
        date_edit,
        datetime_edit,
        error_display,
    ])

    fill = urwid.Filler(pile, 'top')
    loop = urwid.MainLoop(fill)
    loop.run()

if __name__ == "__main__":
    main()

Output

Below is an example output that contains an invalid date that is not corrected (first 2024-02-29 is entered, and then the year is moved down 1.

Context

Suppose one would like two, modular, input boxes in which one can enter a date in format yyyy-mm-dd and optionally the time in format: HH-MM, like:

Please enter the date in format YYYY-MM-DD, (and optionally the time in format HH-MM )`
<highlighed input box when selected>

That:

1. Directly shows a warning/red text (perhaps at the top right of the screen), that says: invalid character entered: "_" if the user tries to type an invalid character, like a.
2. Has a (customizable) shortcut for help, like ctrl+h, which opens a help screen a bit like this example.
3. allows moving to the next box using either the enter button
4. Allows selecting the auto-completed suggestion using the tab button
5. Allows selecting the digits using up and down arrows, and going to the next/previous digit using the left, right arrow, whilst only showing valid options, e.g. if february as month is selected, it only allows selecting 1 to 28/29 (instead of showing 1 to 30/31).
6. Highlights the text box as red if the user selected an invalid date. E.g. selecting 2024-02-29 and then going down on the date one year, e.g. 2023-02-29. (Because 2023 is not a leap year).

Question

How could one build that in urwid?

Attempt

I am experiencing some difficulties in implementing the features 1, 2, 3, 4 and 6 in the MWE below:

import urwid
import datetime
import calendar

class DateTimeEdit(urwid.Edit):
    # ... (the DateTimeEdit class from the previous response) ...
    def __init__(self, caption, date_only=False, **kwargs):
        super().__init__(caption, **kwargs)
        self.date_only = date_only
        self.error_text = urwid.Text("")
        self.help_text = urwid.Text("")
        self.date_parts = [4, 2, 2]  # year, month, day
        self.time_parts = [2, 2]  # hour, minute
        self.current_part = 0
        self.date_values = [None, None, None]
        self.time_values = [None, None]
        self.date_separator = "-"
        self.time_separator = ":"

    def valid_char(self, ch):
        if ch.isdigit() or ch == self.date_separator or (not self.date_only and ch == self.time_separator):
            return True
        else:
            self.error_text.set_text(f"invalid character entered: '{ch}'")
            return False

    def keypress(self, size, key):
        if key == 'ctrl h':
            self.show_help()
            return None
        if key == 'enter':
            return 'enter'  # Signal to move to the next box
        if key == 'tab':
            # Implement suggestion selection here
            return None
        if key == 'left':
            self.move_to_previous_part()
            return None
        if key == 'right':
            self.move_to_next_part()
            return None
        if key == 'up' or key == 'down':
            self.adjust_value(key)
            return None

        result = super().keypress(size, key)
        if result:
            self.error_text.set_text("")  # Clear error on valid input
            self.update_values()
        return result

    def update_values(self):
        text = self.get_edit_text()
        if self.date_only:
            parts = text.split(self.date_separator)
            for i, part in enumerate(parts):
                if part:
                    try:
                        self.date_values[i] = int(part)
                    except ValueError:
                        self.date_values[i] = None
        else:
            date_time_parts = text.split(" ")
            if len(date_time_parts) > 0:
                date_parts = date_time_parts[0].split(self.date_separator)
                for i, part in enumerate(date_parts):
                    if part:
                        try:
                            self.date_values[i] = int(part)
                        except ValueError:
                            self.date_values[i] = None
            if len(date_time_parts) > 1:
                time_parts = date_time_parts[1].split(self.time_separator)
                for i, part in enumerate(time_parts):
                    if part:
                        try:
                            self.time_values[i] = int(part)
                        except ValueError:
                            self.time_values[i] = None

    def move_to_next_part(self):
        if self.date_only:
            if self.current_part < len(self.date_parts) - 1:
                self.current_part += 1
        else:
            if self.current_part < len(self.date_parts) + len(self.time_parts) - 1:
                self.current_part += 1
        self.update_cursor()

    def move_to_previous_part(self):
        if self.current_part > 0:
            self.current_part -= 1
        self.update_cursor()

    def update_cursor(self):
        # Calculate cursor position based on current_part
        cursor_pos = 0
        if self.date_only:
            for i in range(self.current_part):
                cursor_pos += self.date_parts[i] + 1
        else:
            if self.current_part < len(self.date_parts):
                for i in range(self.current_part):
                    cursor_pos += self.date_parts[i] + 1
            else:
                cursor_pos = sum(self.date_parts) + 1
                for i in range(self.current_part - len(self.date_parts)):
                    cursor_pos += self.time_parts[i] + 1
        self.set_edit_pos(cursor_pos)

    def adjust_value(self, direction):
        if self.date_only:
            if self.current_part == 0:
                self.adjust_year(direction)
            elif self.current_part == 1:
                self.adjust_month(direction)
            elif self.current_part == 2:
                self.adjust_day(direction)
        else:
            if self.current_part == 0:
                self.adjust_year(direction)
            elif self.current_part == 1:
                self.adjust_month(direction)
            elif self.current_part == 2:
                self.adjust_day(direction)
            elif self.current_part == 3:
                self.adjust_hour(direction)
            elif self.current_part == 4:
                self.adjust_minute(direction)
        self.update_text()

    def adjust_year(self, direction):
        if self.date_values[0] is None:
            self.date_values[0] = 2024  # Default year
        if direction == 'up':
            self.date_values[0] += 1
        elif direction == 'down':
            self.date_values[0] -= 1

    def adjust_month(self, direction):
        if self.date_values[1] is None:
            self.date_values[1] = 1
        if direction == 'up':
            self.date_values[1] = (self.date_values[1] % 12) + 1
        elif direction == 'down':
            self.date_values[1] = (self.date_values[1] - 2) % 12 + 1

    def adjust_day(self, direction):
        if self.date_values[2] is None:
            self.date_values[2] = 1
        max_days = self.get_max_days()
        if direction == 'up':
            self.date_values[2] = (self.date_values[2] % max_days) + 1
        elif direction == 'down':
            self.date_values[2] = (self.date_values[2] - 2) % max_days + 1

    def adjust_hour(self, direction):
        if self.time_values[0] is None:
            self.time_values[0] = 0
        if direction == 'up':
            self.time_values[0] = (self.time_values[0] + 1) % 24
        elif direction == 'down':
            self.time_values[0] = (self.time_values[0] - 1) % 24

    def adjust_minute(self, direction):
        if self.time_values[1] is None:
            self.time_values[1] = 0
        if direction == 'up':
            self.time_values[1] = (self.time_values[1] + 1) % 60
        elif direction == 'down':
            self.time_values[1] = (self.time_values[1] - 1) % 60

    def get_max_days(self):
        if self.date_values[0] is None or self.date_values[1] is None:
            return 31
        try:
            _, max_days = calendar.monthrange(self.date_values[0], self.date_values[1])
            return max_days
        except ValueError:
            return 31

    def update_text(self):
        date_str = self.date_separator.join(map(lambda x: str(x).zfill(2) if x is not None else "00", self.date_values))
        if self.date_only:
            self.set_edit_text(date_str)
        else:
            time_str = self.time_separator.join(map(lambda x: str(x).zfill(2) if x is not None else "00", self.time_values))
            self.set_edit_text(date_str + " " + time_str)


import urwid
import datetime
import calendar

# (DateTimeEdit class code from previous responses)

def main():
    date_edit = DateTimeEdit("Date (YYYY-MM-DD): ", date_only=True)
    datetime_edit = DateTimeEdit("Date & Time (YYYY-MM-DD HH:MM): ")

    error_display = urwid.Text("")
    date_edit.error_text = error_display
    datetime_edit.error_text = error_display

    pile = urwid.Pile([
        urwid.Text("Enter Date and/or Time:"),
        date_edit,
        datetime_edit,
        error_display,
    ])

    fill = urwid.Filler(pile, 'top')
    loop = urwid.MainLoop(fill)
    loop.run()

if __name__ == "__main__":
    main()

Output

Below is an example output that contains an invalid date that is not corrected (first 2024-02-29 is entered, and then the year is moved down 1.

• python
• tui
• urwid

1 Answer 1

Here's a solution that addresses your issues in the DateTimeEdit class for urwid:

def valid_char(self, ch):
    if ch.isdigit() or ch == self.date_separator or (not self.date_only and ch == self.time_separator):
        return True
    else:
        self.error_text.set_text(f"invalid character entered: '{ch}'")
        return False

def keypress(self, size, key):
    # For feature 1: Invalid character warning
    if len(key) == 1 and not self.valid_char(key):
        # Don't process the invalid character
        return None
        
    # For feature 2: Help shortcut
    if key == 'ctrl h':
        self.show_help()
        return None
    
    # For feature 3: Enter to move to next box
    if key == 'enter':
        # Return 'down' to move focus to next widget
        return 'down'
    
    # For features 4 & 5: Navigation and selection with arrow keys
    if key in ('up', 'down', 'left', 'right', 'tab'):
        if key == 'tab':
            # Auto-complete logic here
            self.auto_complete_suggestion()
            return None
        elif key in ('left', 'right'):
            if key == 'left':
                self.move_to_previous_part()
            else:
                self.move_to_next_part()
            return None
        elif key in ('up', 'down'):
            self.adjust_value(key)
            return None
    
    result = super().keypress(size, key)
    self.update_values()
    
    # For feature 6: Validate the date
    self.validate_date()
    
    return result

def validate_date(self):
    """Check if current date is valid and highlight if not"""
    if all(v is not None for v in self.date_values):
        try:
            # Try to create a date object
            datetime.date(self.date_values[0], self.date_values[1], self.date_values[2])
            # Date is valid, reset highlight
            self._attr = {}
        except ValueError:
            # Date is invalid, set highlight to red
            self._attr = {None: 'error'}
            self.error_text.set_text("Invalid date selected")
    
    # Update display
    self._invalidate()

For this to work fully, you need to:

1. Implement the show_help() method for feature 2
2. Implement auto_complete_suggestion() for feature 4
3. Add a palette definition in your main function:

   palette = [('error', 'white', 'dark red')]
   loop = urwid.MainLoop(fill, palette=palette)
   

The key additions here are properly validating characters during input, using 'down' as the return value for 'enter' to move focus, implementing date validation, and setting up error highlighting.