Search start_date property does not support single-value for datetime

[avbentem]

The datetime attribute of a search request is defined to be an exact datetime, or a range with possible open ends on either side:

Parameter	Type	Source API	Description
...
datetime	string	OAFeat	Single date+time, or a range ('/' separator), formatted to RFC 3339, section 5.6. Use double dots .. for open date ranges.
...

But today, the start_date and end_date properties are implemented as:

stac-pydantic/stac_pydantic/api/search.py

Lines 46 to 62 in 79248a2

	@property
	def start_date(self) -> Optional[dt]:
	values = (self.datetime or "").split("/")
	if len(values) == 1:
	return None
	if values[0] == ".." or values[0] == "":
	return None
	return parse_rfc3339(values[0])
	@property
	def end_date(self) -> Optional[dt]:
	values = (self.datetime or "").split("/")
	if len(values) == 1:
	return parse_rfc3339(values[0])
	if values[1] == ".." or values[1] == "":
	return None
	return parse_rfc3339(values[1])

This implies that for a single value, start_date is left empty and only end_date is set:

datetime	start_date	end_date
2012-07-02T00:00:00Z	None	2012-07-02 00:00
2012-07-02T00:00:00Z/..	2012-07-02 00:00	None
../2012-07-03T23:59:59Z	None	2012-07-03 00:00

I very much assume for a single datetime (the first case above) both start_date and end_date should be set to the same value?

(I can submit a PR if this is indeed a bug. It's just line 50 that should be changed from return None into return parse_rfc3339(values[0]). EDIT: also def validate_datetime would need a fix; see below.)

[avbentem]

@jonhealy1 I see your 👍 but now I also ran into this:

stac-pydantic/stac_pydantic/api/search.py

Lines 103 to 110 in 79248a2

	@field_validator("datetime")
	@classmethod
	def validate_datetime(cls, v: str) -> str:
	if "/" in v:
	values = v.split("/")
	else:
	# Single date is interpreted as end date
	values = ["..", v]

So, its implementation seems quite specific. Also in the follwing PR the same behavior is kept, but maybe that's unintentional:

https://github.com/stac-utils/stac-pydantic/pull/135/files#diff-cedfbbe7e0d06171e4f3cdfab0c02e1712111610dc9419080077b4d15a1c3d85R109-R111

Related discussion: stac-utils/stac-fastapi#688

[vincentsarago]

note, this is the same issue as #79