add datetime validation for collection time intervals

CHANGELOG.md

@@ -1,6 +1,8 @@
 
 ## Unreleased
 
+- Add datetime validation for collection's time intervals (Must follow [`RFC 3339, section 5.6.`](https://datatracker.ietf.org/doc/html/rfc3339#section-5.6))
+
 ## 3.2.0 (2025-03-20)
 
 - Move `validate_bbox` and `validate_datetime` field validation functions outside the Search class (to enable re-utilization)

CONTRIBUTING.md

@@ -0,0 +1,26 @@
+# Contributing
+
+Issues and pull requests are more than welcome.
+
+**dev install**
+
+```bash
+git clone https://github.com/stac-utils/stac-pydantic.git
+cd stac-pydantic
+python -m pip install -e ".[dev]"
+```
+
+You can then run the tests with the following command:
+
+```sh
+python -m pytest --cov stac_pydantic --cov-report term-missing
+```
+
+
+**pre-commit**
+
+This repo is set to use `pre-commit` to run *ruff*, *pydocstring* and mypy when committing new code.
+
+```bash
+pre-commit install
+```

stac_pydantic/api/search.py

@@ -1,5 +1,5 @@
 from datetime import datetime as dt
-from typing import Any, Dict, List, Optional, Tuple, Union, cast
+from typing import Any, Dict, List, Optional, Union
 
 from geojson_pydantic.geometries import (
     GeometryCollection,
@@ -10,13 +10,18 @@
     Point,
     Polygon,
 )
-from pydantic import AfterValidator, BaseModel, Field, TypeAdapter, model_validator
+from pydantic import AfterValidator, BaseModel, Field, model_validator
 from typing_extensions import Annotated
 
 from stac_pydantic.api.extensions.fields import FieldsExtension
 from stac_pydantic.api.extensions.query import Operator
 from stac_pydantic.api.extensions.sort import SortExtension
-from stac_pydantic.shared import BBox, UtcDatetime
+from stac_pydantic.shared import (
+    BBox,
+    str_to_datetimes,
+    validate_bbox,
+    validate_datetime,
+)
 
 Intersection = Union[
     Point,
@@ -28,78 +33,6 @@
     GeometryCollection,
 ]
 
-SearchDatetime = TypeAdapter(Optional[UtcDatetime])
-
-
-def validate_bbox(v: Optional[BBox]) -> Optional[BBox]:
-    """Validate BBOX value."""
-    if v:
-        # Validate order
-        if len(v) == 4:
-            xmin, ymin, xmax, ymax = cast(Tuple[int, int, int, int], v)
-
-        elif len(v) == 6:
-            xmin, ymin, min_elev, xmax, ymax, max_elev = cast(
-                Tuple[int, int, int, int, int, int], v
-            )
-            if max_elev < min_elev:
-                raise ValueError(
-                    "Maximum elevation must greater than minimum elevation"
-                )
-        else:
-            raise ValueError("Bounding box must have 4 or 6 coordinates")
-
-        # Validate against WGS84
-        if xmin < -180 or ymin < -90 or xmax > 180 or ymax > 90:
-            raise ValueError("Bounding box must be within (-180, -90, 180, 90)")
-
-        if ymax < ymin:
-            raise ValueError("Maximum latitude must be greater than minimum latitude")
-
-    return v
-
-
-def str_to_datetimes(value: str) -> List[Optional[dt]]:
-    # Split on "/" and replace no value or ".." with None
-    values = [v if v and v != ".." else None for v in value.split("/")]
-
-    # Cast because pylance gets confused by the type adapter and annotated type
-    dates = cast(
-        List[Optional[dt]],
-        [
-            # Use the type adapter to validate the datetime strings, strict is necessary
-            # due to pydantic issues #8736 and #8762
-            SearchDatetime.validate_strings(v, strict=True) if v else None
-            for v in values
-        ],
-    )
-    return dates
-
-
-def validate_datetime(v: Optional[str]) -> Optional[str]:
-    """Validate Datetime value."""
-    if v is not None:
-        dates = str_to_datetimes(v)
-
-        # If there are more than 2 dates, it's invalid
-        if len(dates) > 2:
-            raise ValueError(
-                "Invalid datetime range. Too many values. Must match format: {begin_date}/{end_date}"
-            )
-
-        # If there is only one date, duplicate to use for both start and end dates
-        if len(dates) == 1:
-            dates = [dates[0], dates[0]]
-
-        # If there is a start and end date, check that the start date is before the end date
-        if dates[0] and dates[1] and dates[0] > dates[1]:
-            raise ValueError(
-                "Invalid datetime range. Begin date after end date. "
-                "Must match format: {begin_date}/{end_date}"
-            )
-
-    return v
-
 
 class Search(BaseModel):
     """

stac_pydantic/collection.py

@@ -1,25 +1,61 @@
-from typing import Any, Dict, List, Literal, Optional, Union
+from typing import Any, Dict, List, Literal, Optional, Tuple, Union
 
-from pydantic import Field
+from pydantic import AfterValidator, Field
+from typing_extensions import Annotated
 
 from stac_pydantic.catalog import _Catalog
-from stac_pydantic.shared import Asset, NumType, Provider, StacBaseModel
+from stac_pydantic.shared import (
+    Asset,
+    BBox,
+    NumType,
+    Provider,
+    StacBaseModel,
+    UtcDatetime,
+)
+
+TInterval = Tuple[Union[UtcDatetime, None], Union[UtcDatetime, None]]
+
+
+def validate_time_interval(v: List[TInterval]) -> List[TInterval]:
+    ivalues = iter(v)
+
+    # The first time interval always describes the overall temporal extent of the data.
+    start, end = next(ivalues)
+    if start and end:
+        assert start < end, f"`Start` time {start} older than `End` time {end}"
+
+    # All subsequent time intervals can be used to provide a more precise
+    # description of the extent and identify clusters of data.
+    for s, e in ivalues:
+        if start and s:
+            if start > s:
+                raise ValueError(
+                    f"`Overall Start` time {start} older than `Start` time {s}"
+                )
+
+        if end and e:
+            if e > end:
+                raise ValueError(
+                    f"`End` time {e} older than `Overall Start` time {end}"
+                )
+
+    return v
 
 
 class SpatialExtent(StacBaseModel):
     """
     https://github.com/radiantearth/stac-spec/blob/v1.0.0/collection-spec/collection-spec.md#spatial-extent-object
     """
 
-    bbox: List[List[NumType]]
+    bbox: List[BBox]
 
 
 class TimeInterval(StacBaseModel):
     """
     https://github.com/radiantearth/stac-spec/blob/v1.0.0/collection-spec/collection-spec.md#temporal-extent-object
     """
 
-    interval: List[List[Union[str, None]]]
+    interval: Annotated[List[TInterval], AfterValidator(validate_time_interval)]
 
 
 class Extent(StacBaseModel):

stac_pydantic/shared.py

@@ -1,6 +1,7 @@
+from datetime import datetime as dt
 from datetime import timezone
 from enum import Enum, auto
-from typing import Any, Dict, List, Optional, Tuple, Union
+from typing import Any, Dict, List, Optional, Tuple, Union, cast
 from warnings import warn
 
 from pydantic import (
@@ -9,6 +10,7 @@
     BaseModel,
     ConfigDict,
     Field,
+    TypeAdapter,
     model_validator,
 )
 from typing_extensions import Annotated, Self
@@ -32,6 +34,8 @@
     AfterValidator(lambda d: d.astimezone(timezone.utc)),
 ]
 
+SearchDatetime = TypeAdapter(Optional[UtcDatetime])
+
 
 class MimeTypes(str, Enum):
     """
@@ -196,3 +200,73 @@ class Asset(StacBaseModel):
     model_config = ConfigDict(
         populate_by_name=True, use_enum_values=True, extra="allow"
     )
+
+
+def str_to_datetimes(value: str) -> List[Optional[dt]]:
+    # Split on "/" and replace no value or ".." with None
+    values = [v if v and v != ".." else None for v in value.split("/")]
+
+    # Cast because pylance gets confused by the type adapter and annotated type
+    dates = cast(
+        List[Optional[dt]],
+        [
+            # Use the type adapter to validate the datetime strings, strict is necessary
+            # due to pydantic issues #8736 and #8762
+            SearchDatetime.validate_strings(v, strict=True) if v else None
+            for v in values
+        ],
+    )
+    return dates
+
+
+def validate_datetime(v: Optional[str]) -> Optional[str]:
+    """Validate Datetime value."""
+    if v is not None:
+        dates = str_to_datetimes(v)
+
+        # If there are more than 2 dates, it's invalid
+        if len(dates) > 2:
+            raise ValueError(
+                "Invalid datetime range. Too many values. Must match format: {begin_date}/{end_date}"
+            )
+
+        # If there is only one date, duplicate to use for both start and end dates
+        if len(dates) == 1:
+            dates = [dates[0], dates[0]]
+
+        # If there is a start and end date, check that the start date is before the end date
+        if dates[0] and dates[1] and dates[0] > dates[1]:
+            raise ValueError(
+                "Invalid datetime range. Begin date after end date. "
+                "Must match format: {begin_date}/{end_date}"
+            )
+
+    return v
+
+
+def validate_bbox(v: Optional[BBox]) -> Optional[BBox]:
+    """Validate BBOX value."""
+    if v:
+        # Validate order
+        if len(v) == 4:
+            xmin, ymin, xmax, ymax = cast(Tuple[int, int, int, int], v)
+
+        elif len(v) == 6:
+            xmin, ymin, min_elev, xmax, ymax, max_elev = cast(
+                Tuple[int, int, int, int, int, int], v
+            )
+            if max_elev < min_elev:
+                raise ValueError(
+                    "Maximum elevation must greater than minimum elevation"
+                )
+        else:
+            raise ValueError("Bounding box must have 4 or 6 coordinates")
+
+        # Validate against WGS84
+        if xmin < -180 or ymin < -90 or xmax > 180 or ymax > 90:
+            raise ValueError("Bounding box must be within (-180, -90, 180, 90)")
+
+        if ymax < ymin:
+            raise ValueError("Maximum latitude must be greater than minimum latitude")
+
+    return v

tests/api/examples/v1.0.0/example-collection-list.json

@@ -63,8 +63,8 @@
              "temporal":{
                 "interval":[
                    [
-                      "2000-03-04T12:00:00.000000Z",
-                      "2006-12-31T12:00:00.000000Z"
+                      "2000-03-04T12:00:00Z",
+                      "2006-12-31T12:00:00Z"
                    ]
                 ]
              }

tests/api/test_collections.py

@@ -9,5 +9,5 @@
 
 def test_collection_list():
     test_collection_list = request(EXAMPLE_COLLECTION_LIST, PATH)
-    valid_collection_list = Collections(**test_collection_list).model_dump()
+    valid_collection_list = Collections(**test_collection_list).model_dump(mode="json")
     dict_match(test_collection_list, valid_collection_list)

tests/conftest.py

@@ -48,7 +48,7 @@ def dict_match(d1: dict, d2: dict):
         # to compare the values as datetime objects.
         elif "datetime" in diff[1]:
             dates = [
-                UtcDatetimeAdapter.validate_strings(date)
+                UtcDatetimeAdapter.validate_strings(date, strict=True)
                 if isinstance(date, str)
                 else date
                 for date in diff[2]