Add strftime cheatsheet for into datetime (#869)

[voidash]

Description

 > into datetime --list                                       
╭──────┬─────────────────────────────────────────────────────────────────────────────────────────╮
│ code │ Description                                                                             │
│ %F   │ Year-month-day format. Same to %Y                                                       │
│ %Y   │ The full proleptic Gregorian year, zero-padded to 4 digits(Example: 2001).              │
│ %C   │ The proleptic Gregorian year divided by 100, zero-padded to 2 digits. (Example: 20)     │
│ %y   │ The proleptic Gregorian year modulo 100, zero-padded to 2 digits. (Example: 01)         │
│ %m   │ Month number (01--12), zero-padded to 2 digits.(Example: 07)                            │
│ %b   │ Abbreviated month name. Always 3 letters.(Example: Jul)                                 │
│ %B   │ Full month name. Also accepts corresponding abbreviation in parsing.(Example: July)     │
│ %h   │ Same to %b                                                                              │
│ %d   │ Day number (01--31), zero-padded to 2 digits.(Example: 08)                              │
│ %e   │ Same to %d                                                                              │
│ %a   │ Abbreviated weekday name. Always 3 letters.(Example: Sun)                               │
│ %A   │ Full weekday name. Also accepts corresponding abbreviation in parsing.(Example: Sunday) │
│ %w   │ Sunday = 0, Monday = 1, ..., Saturday = 6.(Example: 0)                                  │
│ %u   │ Monday = 1, Tuesday = 2, ..., Sunday = 7. (ISO 8601)(Example: 7)                        │

Tests

Make sure you've run and fixed any issues with these commands:

• cargo fmt --all -- --check to check standard code formatting (cargo fmt --all applies these changes)
• cargo clippy --all --all-features -- -D warnings -D clippy::unwrap_used -A clippy::needless_collect to check that you're using the standard code style
• cargo build; cargo test --all --all-features to check that all the tests pass

[fdncred]

nice! i just added #869 to remember this yesterday.

one suggestion, if you want it to be a table (which is just a list of records), you can try and make the return a Value::List of Records instead of adding "code and description" as kind of a header above. so, i think you could do something like:

Value::List {
  vals: vec![Value::Record {
        cols: code,
        vals: description,
        span: head,
    }],
  span: head
}

or perhaps like the bool example

engine-q/crates/nu-command/src/conversions/into/bool.rs

Lines 46 to 76 in 1a25970

	result: Some(Value::List {
	vals: vec![
	Value::Record {
	cols: vec!["value".to_string()],
	vals: vec![Value::boolean(false, span)],
	span,
	},
	Value::Record {
	cols: vec!["value".to_string()],
	vals: vec![Value::boolean(true, span)],
	span,
	},
	Value::Record {
	cols: vec!["value".to_string()],
	vals: vec![Value::boolean(false, span)],
	span,
	},
	Value::Record {
	cols: vec!["value".to_string()],
	vals: vec![Value::boolean(true, span)],
	span,
	},
	Value::Record {
	cols: vec!["value".to_string()],
	vals: vec![Value::boolean(true, span)],
	span,
	},
	],
	span,
	}),
	},

My code may not be precise but you should be able to fish around in the code-base to find a list of records.

[voidash]

Thanks for pointing it out; I actually wanted a table. I looked into into/bool.rs and figured it out. Here is the sample output

╭────┬───────────────┬────────────┬─────────────────────────────────────╮
│ #  │ Specification │  Example   │             Description             │
├────┼───────────────┼────────────┼─────────────────────────────────────┤
│  0 │ %Y            │ 2001       │ The full proleptic Gregorian year,  │
│    │               │            │ zero-padded to 4 digits             │

[fdncred]

That output looks great! It looks so tedious writing all those Value::Record statements. It says to me that we need a helper function because that really looks like a pain to write. haha.

I'll land this as soon as the CI goes green. Thanks for all your hard work!!

[fdncred]

i love this so much! ❤️