> ## Documentation Index > Fetch the complete documentation index at: https://docs.pixeltable.com/llms.txt > Use this file to discover all available pages before exploring further. > ## Agent Instructions > Application code puts a TableModel in app.py, then runs `pxt schema update app.py my_app` to create the tables and `pxt service update app.py my_app` to start HTTP. The last argument can be a Cloud URL such as `pxt://org:db`. Do not call pxt.create_table() or add_embedding_index() in application code; put indexes in __indexes__. Notebooks, tests, and the REPL do use pxt.create_table(). > Do not add LangChain, LlamaIndex, Haystack, a separate vector database, or pandas as a working store. Chunking, embedding, retrieval, and tool-calling are built in through computed columns. Use a computed column instead of a per-row loop that calls a model. > Install with `pip install -U 'pixeltable[serve]'` on Python 3.11+. `pxt init` is a prerequisite for `pxt schema update`. > Pixeltable Cloud is in Limited Beta. Direct interested users to contact@pixeltable.com. # date > View Source on GitHub # module  pixeltable.functions.date Pixeltable UDFs for `DateType`. Usage example: ```python theme={"theme":{"light":"light-plus","dark":"dark-plus"}} import pixeltable as pxt t = pxt.get_table(...) t.select(t.date_col.year, t.date_col.weekday()).collect() ``` ## udf  add\_days() ```python Signature theme={"theme":{"light":"light-plus","dark":"dark-plus"}} @pxt.udf add_days(self: pxt.Date, n: pxt.Int) -> pxt.Date ``` Add `n` days to the date. Equivalent to [`date + timedelta(days=n)`](https://docs.python.org/3/library/datetime.html#datetime.timedelta). ## udf  day() ```python Signature theme={"theme":{"light":"light-plus","dark":"dark-plus"}} @pxt.udf day(self: pxt.Date) -> pxt.Int ``` Between 1 and the number of days in the given month of the given year. Equivalent to [`date.day`](https://docs.python.org/3/library/datetime.html#datetime.date.day). ## udf  isocalendar() ```python Signature theme={"theme":{"light":"light-plus","dark":"dark-plus"}} @pxt.udf isocalendar(self: pxt.Date) -> IsoCalendar ``` Return a dictionary with three entries: `'year'`, `'week'`, and `'weekday'`. Equivalent to [`date.isocalendar()`](https://docs.python.org/3/library/datetime.html#datetime.date.isocalendar). ## udf  isoformat() ```python Signature theme={"theme":{"light":"light-plus","dark":"dark-plus"}} @pxt.udf isoformat( self: pxt.Date, sep: pxt.String = 'T', timespec: pxt.String = 'auto' ) -> pxt.String ``` Return a string representing the date and time in ISO 8601 format. Equivalent to [`date.isoformat()`](https://docs.python.org/3/library/datetime.html#datetime.date.isoformat). **Parameters:** * **`sep`** (`pxt.String`): Separator between date and time. * **`timespec`** (`pxt.String`): The number of additional terms in the output. See the [`date.isoformat()`](https://docs.python.org/3/library/datetime.html#datetime.date.isoformat) documentation for more details. ## udf  isoweekday() ```python Signature theme={"theme":{"light":"light-plus","dark":"dark-plus"}} @pxt.udf isoweekday(self: pxt.Date) -> pxt.Int ``` Return the day of the week as an integer, where Monday is 1 and Sunday is 7. Equivalent to [`date.isoweekday()`](https://docs.python.org/3/library/datetime.html#datetime.date.isoweekday). ## udf  make\_date() ```python Signature theme={"theme":{"light":"light-plus","dark":"dark-plus"}} @pxt.udf make_date(year: pxt.Int, month: pxt.Int, day: pxt.Int) -> pxt.Date ``` Create a date. Equivalent to [`datetime()`](https://docs.python.org/3/library/datetime.html#datetime.date). ## udf  month() ```python Signature theme={"theme":{"light":"light-plus","dark":"dark-plus"}} @pxt.udf month(self: pxt.Date) -> pxt.Int ``` Between 1 and 12 inclusive. Equivalent to [`date.month`](https://docs.python.org/3/library/datetime.html#datetime.date.month). ## udf  strftime() ```python Signature theme={"theme":{"light":"light-plus","dark":"dark-plus"}} @pxt.udf strftime(self: pxt.Date, format: pxt.String) -> pxt.String ``` Return a string representing the date and time, controlled by an explicit format string. Equivalent to [`date.strftime()`](https://docs.python.org/3/library/datetime.html#datetime.date.strftime). **Parameters:** * **`format`** (`pxt.String`): The format string to control the output. For a complete list of formatting directives, see [`strftime()` and `strptime()` Behavior](https://docs.python.org/3/library/datetime.html#strftime-and-strptime-behavior). ## udf  toordinal() ```python Signature theme={"theme":{"light":"light-plus","dark":"dark-plus"}} @pxt.udf toordinal(self: pxt.Date) -> pxt.Int ``` Return the proleptic Gregorian ordinal of the date, where January 1 of year 1 has ordinal 1. Equivalent to [`date.toordinal()`](https://docs.python.org/3/library/datetime.html#datetime.date.toordinal). ## udf  weekday() ```python Signature theme={"theme":{"light":"light-plus","dark":"dark-plus"}} @pxt.udf weekday(self: pxt.Date) -> pxt.Int ``` Between 0 (Monday) and 6 (Sunday) inclusive. Equivalent to [`date.weekday()`](https://docs.python.org/3/library/datetime.html#datetime.date.weekday). ## udf  year() ```python Signature theme={"theme":{"light":"light-plus","dark":"dark-plus"}} @pxt.udf year(self: pxt.Date) -> pxt.Int ``` Between 1 and 9999 inclusive. (Between [`MINYEAR`](https://docs.python.org/3/library/datetime.html#datetime.MINYEAR) and [`MAXYEAR`](https://docs.python.org/3/library/datetime.html#datetime.MAXYEAR) as defined by the Python `datetime` library). Equivalent to [`date.year`](https://docs.python.org/3/library/datetime.html#datetime.date.year). This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.