The date widget provides a versatile HTML control for entering
dates in a variety of formats. The widget operates in conjunction
with various template::util::date functions in order
to validate and manipulate the user's input. Please see the
demo pages for some examples
of the widget's behavior.
The widget's value is a Date object, defined in
template::util::date. The date object stores 7 fields:
the year, month, day, hours, minutes, seconds, and the format
in which these values should be displayed. The function
template::util::date::create can be used to instantiate
a blank date:
proc template::util::date::create {
{year {}} {month {}} {day {}} {hours {}}
{minutes {}} {seconds {}} {format "YYYY/MM/DD"}
} {
return [list $year $month $day $hours $minutes $seconds $format]
}
The two functions template::util::date::get_property and
template::util::date::set_property are used to get or
set the fields of a Date object. The get_property function
accepts the desired field and the Date object, and returns the
value of the field:
proc template::util::date::get_property { what date } {
...
}
The set_property function accepts the field, the Date
object and the new value, and returns the modified Date object:
proc template::util::date::set_property { what date value } {
...
}
The fields which can be accessed or changed are summarized below:
| Field | Get ? | Set ? | Meaning | Sample Value |
|---|---|---|---|---|
year | Yes | Yes | The 4-digit year | 2000 |
month | Yes | Yes | The month, January = 1 | 8 |
day | Yes | Yes | The day of month | 21 |
hours | Yes | Yes | The hour, in 24-hour format | 23 |
minutes | Yes | Yes | The minute | 59 |
seconds | Yes | Yes | The second | 59 |
format | Yes | Yes | The format (see below for a detailed explanation) | YYYY/MM/DD |
long_month_name | Yes | The symbolic month name | January |
|
short_month_name | Yes | The abbreviated month name | Jan |
|
days_in_month | Yes | The number of days in the month stored in the Date object; will return an empty string if the month or the year are undefined. Takes into account the leap years. | 29 |
|
short_year | Yes | Yes | The 2-digit year. When mutating, 2000 is added to the year if it is less than 69; otherwise, 1900 is added to the year. | 99 |
short_hours | Yes | Yes | The hour, in 12-hour format. When mutating, the hour is always assumed
to be in the "a.m." range; the ampm field
may be used to change this. |
3 |
ampm | Yes | Yes | The meridian indicator: either am or pm.
Can be used in conjunction with the short_hour field
in order to completely specify the hour. |
am |
not_null | Yes | This field will be 1 if and only if at least one of the date fields (year, month, date, hours, minutes or seconds) is present in the Date object. Otherwise, this field will be 0. | 1 |
|
sql_date | Yes | The SQL code fragment representing the date stored in the Date object. | to_date('2000/08/12 11:15:00', 'YYYY/MM/DD HH24:MI:SS') |
|
clock | Yes | Yes | The value of the date in the same format as the value returned by the
clock seconds function. The clock function appears
to be locale-dependent and therefore unreliable; however, manipulating the
clock value with clock scan is currently the only way to
perform arithmetic operations on dates, such as adding a day, comparing
two dates, etc. |
(An integer representing the number of elapsed seconds) |
For example, the following code produces the tomorrow's date in SQL:
# Create a blank date set today_date [template::util::date::create] # Get the tomorrow's date set clock_value [clock scan "1 day" -base [clock seconds]] set tomorrow_date [template::util::date::set_property \ clock $today_date $clock_value] # Get the SQL value set tomorrow_sql [template::util::date::get_property \ sql_date $tomorrow_date]
The widget is created with the usual template::element create
statement, with the datatype and widget set to date. In addition,
the element requires a -format switch, which specifies the format
for the date, as follows:
| Option | Format | Meaning |
|---|---|---|
-format long |
YYYY/MM/DD HH24:MI:SS |
The full widget including the date and the time |
-format short |
YYYY/MM/DD |
The widget capable of entering the date only, without the time |
-format time |
HH24/MI/SS |
The widget capable of entering the time only, without the date |
-format american |
MM/DD/YY |
The widget representing the more familiar American date |
-format expiration |
DD/YY |
An expiration date, as it may appear on a credit card |
-format custom string |
Custom format | See below |
Any other value for the format flag is interpreted as a
custom format string. The custom format string should consist of format
specifiers separated by any of /\-.: or spaces. The valid
format specifiers are as follows:
| Format Specifier | Field | Default Widget | |
|---|---|---|---|
YYYY | year | Input box, 4 characters | |
YY | short_year | Input box, 2 characters | |
MM | month | Selection list | |
MON | month |
Selection list of abbreviated month names | |
MONTH | month |
Selection list of full month names | |
DD | day | Selection list | |
HH12 | short_hours |
Selection list from 1 to 12 | |
HH24 | hours |
Selection list from 0 to 23 | |
MI | minutes |
Selection list from 0 to 60, skipping every 5 minutes | |
SS | seconds |
Selection list from 0 to 60, skipping every 5 seconds | |
AM | ampm |
Selection list of "A.M." and "P.M." |
Any format specifier may be followed by a lowercase t, in order
to force the widget to use an input box (instead of a selection list)
for entering the specified date fragment.
The -format switch is required, but the date widget also supports
the following optional switches:
| Switch | Meaning | Example |
|---|---|---|
-field_interval interval |
Specifies a custom interval for the given field, as a list of three values: the starting value, the ending value, and the step | -minute_interval {0 59 5} |
-help |
Causes the date widget to display a description of each date fragment widget showing the purpose of the widget, such as "Year" or "24-Hour" | -help |
Examples of various Date widgets can be found on the demo pages.