QGIS/resources/function_help/json/day_of_week

{
  "name": "day_of_week",
  "type": "function",
  "groups": ["Date and Time"],
  "description": "Returns the day of the week for a specified date or datetime. The returned value ranges from 0 to 6, where 0 corresponds to a Sunday and 6 to a Saturday.",
  "arguments": [{
    "arg": "date",
    "description": "date or datetime value"
  }],
  "examples": [{
    "expression": "day_of_week(to_date('2015-09-21'))",
    "returns": "1"
  }],
  "tags": ["week", "day", "specified", "datetime", "corresponds", "ranges", "date", "saturday"]
}