feat: add xarray dataset coordinate endpoint

docs/src/advanced/Extensions.md

@@ -65,7 +65,7 @@ class FactoryExtension(metaclass=abc.ABCMeta):
 
 #### titiler.xarray.DatasetMetadataExtension
 
-- Goal: adds `/dataset/`, `/dataset/keys` and `/datasets/dict` endpoints which return metadata about a multidimensional Dataset (not a DataArray)
+- Goal: adds `/dataset/`, `/dataset/keys`, `/dataset/dict`, `/dataset/dimensions` and `/dataset/coordinates/{name}` endpoints which return metadata about a multidimensional Dataset (not a DataArray)
 
 #### titiler.mosaic.extensions.wmts.wmtsExtension
 

src/titiler/xarray/tests/test_factory.py

@@ -43,10 +43,11 @@ def test_tiler_factory():
 
     md = TilerFactory(
         router_prefix="/md",
-        # /dataset, /dataset/dict, /dataset/keys
+        # /dataset, /dataset/dict, /dataset/keys, /dataset/dimensions,
+        # /dataset/coordinates/{name}
         extensions=[DatasetMetadataExtension()],
     )
-    assert len(md.router.routes) == 18
+    assert len(md.router.routes) == 20
 
     app = FastAPI()
     app.include_router(md.router, prefix="/md")
@@ -69,7 +70,7 @@ def app():
         ],
         reader=FsReader,
     )
-    assert len(md.router.routes) == 18
+    assert len(md.router.routes) == 20
 
     app = FastAPI()
     app.include_router(md.router, prefix="/md")
@@ -86,7 +87,7 @@ def app_zarr():
             DatasetMetadataExtension(),
         ],
     )
-    assert len(md.router.routes) == 18
+    assert len(md.router.routes) == 20
 
     app = FastAPI()
     app.include_router(md.router, prefix="/md")
@@ -115,6 +116,45 @@ def test_dataset_extension(filename, app):
     assert "text/html" in resp.headers["content-type"]
 
 
+def test_dataset_dimensions(app):
+    """Test dimension names and sizes."""
+    resp = app.get("/md/dataset/dimensions", params={"url": dataset_2d_nc})
+    assert resp.status_code == 200
+    assert resp.headers["content-type"] == "application/json"
+    assert resp.json() == {"y": 1000, "x": 2000}
+
+
+def test_dataset_coordinate(app):
+    """Test coordinate metadata and values."""
+    resp = app.get(
+        "/md/dataset/coordinates/x",
+        params={"url": dataset_2d_nc},
+    )
+    assert resp.status_code == 200
+    assert resp.headers["content-type"] == "application/json"
+    coordinate = resp.json()
+    assert coordinate["name"] == "x"
+    assert coordinate["dims"] == ["x"]
+    assert coordinate["data"][:2] == [-170.0, -169.83]
+
+    resp = app.get(
+        "/md/dataset/coordinates/time",
+        params={"url": dataset_3d_nc},
+    )
+    assert resp.status_code == 200
+    assert resp.json()["data"] == [
+        "2022-01-01T00:00:00",
+        "2023-01-01T00:00:00",
+    ]
+
+    resp = app.get(
+        "/md/dataset/coordinates/missing",
+        params={"url": dataset_2d_nc},
+    )
+    assert resp.status_code == 404
+    assert resp.json() == {"detail": "Coordinate 'missing' not found"}
+
+
 @pytest.mark.parametrize(
     "filename",
     [dataset_2d_nc, dataset_3d_nc, dataset_3d_zarr],

src/titiler/xarray/titiler/xarray/extensions.py

@@ -7,7 +7,7 @@
 
 import xarray
 from attrs import define
-from fastapi import Depends, Query
+from fastapi import Depends, HTTPException, Query
 from rio_tiler.constants import WGS84_CRS
 from starlette.responses import HTMLResponse
 
@@ -102,6 +102,39 @@ def dataset_metadata_dict(
             with self.dataset_opener(src_path, **io_params.as_dict()) as ds:
                 return ds.to_dict(data=False)
 
+        @factory.router.get(
+            "/dataset/dimensions",
+            response_model=dict[str, int],
+            responses={200: {"description": "Returns the Dataset dimension sizes."}},
+        )
+        def dataset_dimensions(
+            src_path=Depends(factory.path_dependency),
+            io_params=Depends(self.io_dependency),
+        ):
+            """Returns the Dataset dimension sizes."""
+            with self.dataset_opener(src_path, **io_params.as_dict()) as ds:
+                return dict(ds.sizes)
+
+        @factory.router.get(
+            "/dataset/coordinates/{name}",
+            responses={
+                200: {"description": "Returns a Dataset coordinate and its values."}
+            },
+        )
+        def dataset_coordinate(
+            name: str,
+            src_path=Depends(factory.path_dependency),
+            io_params=Depends(self.io_dependency),
+        ):
+            """Returns a Dataset coordinate and its values."""
+            with self.dataset_opener(src_path, **io_params.as_dict()) as ds:
+                try:
+                    return ds.coords[name].to_dict(data=True)
+                except KeyError as e:
+                    raise HTTPException(
+                        status_code=404, detail=f"Coordinate '{name}' not found"
+                    ) from e
+
         @factory.router.get(
             "/dataset/keys",
             response_model=list[str],