django common filters add : String addition, number addition, list addition, if it fails, it will return an empty string. default: Provides a default value to be used when this value is considered False by django. For example: empty string, None. Different from default_if_none, this only uses the default value when the variable is None. first: Returns the first value in the list. last: Returns the last value in the list. date: formatted date and time. time: formatted time. join: The same usage as join in python. length: Returns the length of the string or array. length_is: Whether the length of the string or array is the specified value. lower: Program all strings to lowercase. truncatechars: According to the parameters given later, truncate characters, if it exceeds, it is represented by .... truncatewords: Same as truncatechars, this one is truncated by one word. The above two have xxx_html type, for html, truncate the characters in the tag, but not truncate the tag. capfirst: Capitalize the first letter. slice: slice list. The usage is the same as the slice operation in python, the interval is closed before opening and then open. striptags: remove all html tags. safe: turn off automatic escaping of variables floatformat: Float format. More can be found in the official documents : https://yiyibooks.cn/xx/Django_1.11.6/ref/templates/builtins.html English: https: //docs.djangoproject.com/en/1.11/ref/templates/builtins/ date time filter format Y: Four-digit year. For example: 1999 y: Year with two digits. Such as: 99 m: two-digit month. Such as: 01, 09 n: One-digit month. Such as: 1, 9, 12 d: two-digit day. Such as: 01,09,31 j: One-digit day. For example: 1,9,31 g: One-digit hour in 12-hour format. Such as: 1, 9, 12 G: 1-digit hour in 24-hour format. Such as: 0, 8, 23 h: two-digit hour in 12-hour format. Such as: 01 , 09, 12 H: Two-digit hour in 24-hour format. Such as: 01,13,24 i: minutes. From 00 -59 s: seconds. from 00 -59