Add simple version of get_queryables

CHANGELOG.md

@@ -21,6 +21,10 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Three tests that were false positives due to out-of-date cassettes [#491](https://github.com/stac-utils/pystac-client/pull/491)
 - Max items checks when paging [#492](https://github.com/stac-utils/pystac-client/pull/492)
 
+### Added
+
+- Support for fetching catalog queryables [#477](https://github.com/stac-utils/pystac-client/pull/477)
+
 ## [v0.6.1] - 2023-03-14
 
 ### Changed

pystac_client/client.py

@@ -26,13 +26,14 @@
     QueryLike,
     SortbyLike,
 )
+from pystac_client.mixins import QueryablesMixin
 from pystac_client.stac_api_io import StacApiIO
 
 if TYPE_CHECKING:
     from pystac.item import Item as Item_Type
 
 
-class Client(pystac.Catalog):
+class Client(pystac.Catalog, QueryablesMixin):
     """A Client for interacting with the root of a STAC Catalog or API
 
     Instances of the ``Client`` class inherit from :class:`pystac.Catalog`
@@ -236,7 +237,9 @@ def from_dict(
         return result
 
     @lru_cache()
-    def get_collection(self, collection_id: str) -> Optional[Collection]:
+    def get_collection(
+        self, collection_id: str
+    ) -> Optional[Union[Collection, CollectionClient]]:
         """Get a single collection from this Catalog/API
 
         Args:
@@ -262,7 +265,7 @@ def get_collection(self, collection_id: str) -> Optional[Collection]:
 
         return None
 
-    def get_collections(self) -> Iterator[Collection]:
+    def get_collections(self) -> Iterator[Union[Collection, CollectionClient]]:
         """Get Collections in this Catalog
 
             Gets the collections from the /collections endpoint if supported,

pystac_client/collection_client.py

@@ -6,13 +6,14 @@
 from pystac_client.conformance import ConformanceClasses
 from pystac_client.exceptions import APIError
 from pystac_client.item_search import ItemSearch
+from pystac_client.mixins import QueryablesMixin
 from pystac_client.stac_api_io import StacApiIO
 
 if TYPE_CHECKING:
     from pystac.item import Item as Item_Type
 
 
-class CollectionClient(pystac.Collection):
+class CollectionClient(pystac.Collection, QueryablesMixin):
     modifier: Callable[[Modifiable], None]
     _stac_io: Optional[StacApiIO]
 
@@ -70,6 +71,15 @@ def from_dict(
         setattr(result, "modifier", modifier)
         return result
 
+    def set_root(self, root: Optional[pystac.Catalog]) -> None:
+        # hook in to set_root and use it for setting _stac_io
+        super().set_root(root=root)
+        if root is not None and root._stac_io is not None:
+            if not isinstance(root._stac_io, StacApiIO):
+                raise ValueError("Root should be a Client object")
+            else:
+                self._stac_io = root._stac_io
+
     def __repr__(self) -> str:
         return "<CollectionClient id={}>".format(self.id)
 
@@ -85,19 +95,11 @@ def get_items(self) -> Iterator["Item_Type"]:
         """
 
         link = self.get_single_link("items")
-        root = self.get_root()
-        if link is not None and root is not None:
-            # error: Argument "stac_io" to "ItemSearch" has incompatible type
-            # "Optional[StacIO]"; expected "Optional[StacApiIO]"  [arg-type]
-            # so we add these asserts
-            stac_io = root._stac_io
-            assert stac_io
-            assert isinstance(stac_io, StacApiIO)
-
+        if link is not None and self._stac_io is not None:
             search = ItemSearch(
                 url=link.href,
                 method="GET",
-                stac_io=stac_io,
+                stac_io=self._stac_io,
                 modifier=self.modifier,
             )
             yield from search.items()
@@ -128,43 +130,39 @@ def get_item(self, id: str, recursive: bool = False) -> Optional["Item_Type"]:
         """
         if not recursive:
             root = self.get_root()
-            assert root
-            stac_io = root._stac_io
-            assert stac_io
-            assert isinstance(stac_io, StacApiIO)
-            items_link = self.get_single_link("items")
-            if root:
+            if root and self._stac_io:
+                items_link = self.get_single_link("items")
                 search_link = root.get_single_link("search")
-            else:
-                search_link = None
-            if (
-                stac_io.conforms_to(ConformanceClasses.FEATURES)
-                and items_link is not None
-            ):
-                url = f"{items_link.href}/{id}"
-                try:
-                    obj = stac_io.read_stac_object(url, root=self)
-                    item = cast(Optional[pystac.Item], obj)
-                except APIError as err:
-                    if err.status_code and err.status_code == 404:
-                        return None
-                    else:
-                        raise err
-                assert isinstance(item, pystac.Item)
-            elif (
-                stac_io.conforms_to(ConformanceClasses.ITEM_SEARCH)
-                and search_link
-                and search_link.href
-            ):
-                item_search = ItemSearch(
-                    url=search_link.href,
-                    method="GET",
-                    stac_io=self._stac_io,
-                    ids=[id],
-                    collections=[self.id],
-                    modifier=self.modifier,
-                )
-                item = next(item_search.items(), None)
+                if (
+                    self._stac_io.conforms_to(ConformanceClasses.FEATURES)
+                    and items_link is not None
+                ):
+                    url = f"{items_link.href}/{id}"
+                    try:
+                        obj = self._stac_io.read_stac_object(url, root=self)
+                        item = cast(Optional[pystac.Item], obj)
+                    except APIError as err:
+                        if err.status_code and err.status_code == 404:
+                            return None
+                        else:
+                            raise err
+                    assert isinstance(item, pystac.Item)
+                elif (
+                    self._stac_io.conforms_to(ConformanceClasses.ITEM_SEARCH)
+                    and search_link
+                    and search_link.href
+                ):
+                    item_search = ItemSearch(
+                        url=search_link.href,
+                        method="GET",
+                        stac_io=self._stac_io,
+                        ids=[id],
+                        collections=[self.id],
+                        modifier=self.modifier,
+                    )
+                    item = next(item_search.items(), None)
+                else:
+                    item = super().get_item(id, recursive=False)
             else:
                 item = super().get_item(id, recursive=False)
         else:

pystac_client/mixins.py

@@ -0,0 +1,51 @@
+from typing import Optional, Dict, Any
+
+import pystac
+
+from pystac_client.exceptions import APIError
+from pystac_client.conformance import ConformanceClasses
+from pystac_client.stac_api_io import StacApiIO
+
+QUERYABLES_REL = "http://www.opengis.net/def/rel/ogc/1.0/queryables"
+QUERYABLES_ENDPOINT = "/queryables"
+
+
+class StacAPIObject(pystac.STACObject):
+    _stac_io: Optional[StacApiIO]
+
+
+class QueryablesMixin(StacAPIObject):
+    """Mixin for adding support for /queryables endpoint"""
+
+    def get_queryables(self) -> Dict[str, Any]:
+        """Return all queryables.
+
+        Output is a dictionary that can be used in ``jsonshema.validate``
+
+        Return:
+            Dict[str, Any]: Dictionary containing queryable fields
+        """
+        if self._stac_io is None:
+            raise APIError("API access is not properly configured")
+
+        self._stac_io.assert_conforms_to(ConformanceClasses.FILTER)
+        url = self._get_queryables_href()
+
+        result = self._stac_io.read_json(url)
+        if "properties" not in result:
+            raise APIError(
+                f"Invalid response from {QUERYABLES_ENDPOINT}: "
+                "expected 'properties' attribute"
+            )
+
+        return result
+
+    def _get_queryables_href(self) -> str:
+        link = self.get_single_link(QUERYABLES_REL)
+        if link is not None:
+            url = link.href
+        else:
+            # The queryables link should be defined at the root, but if it is not
+            # try to guess the url
+            url = f"{self.self_href.rstrip('/')}{QUERYABLES_ENDPOINT}"
+        return url

tests/cassettes/test_client/TestQueryables.test_get_queryables.yaml

@@ -0,0 +1,130 @@
+interactions:
+- request:
+    body: null
+    headers:
+      Accept:
+      - '*/*'
+      Accept-Encoding:
+      - gzip, deflate
+      Connection:
+      - keep-alive
+      User-Agent:
+      - python-requests/2.28.2
+    method: GET
+    uri: https://planetarycomputer.microsoft.com/api/stac/v1
+  response:
+    body:
+      string: !!binary |
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+    headers:
+      Access-Control-Allow-Credentials:
+      - 'true'
+      Access-Control-Allow-Origin:
+      - '*'
+      Content-Encoding:
+      - gzip
+      Content-Length:
+      - '2906'
+      Content-Type:
+      - application/json
+      Date:
+      - Wed, 12 Apr 2023 18:24:59 GMT
+      Strict-Transport-Security:
+      - max-age=15724800; includeSubDomains
+      Vary:
+      - Accept-Encoding
+      X-Azure-Ref:
+      - 0fPc2ZAAAAADutojn4rB+S6IokbBhkP27RVdSMzBFREdFMDUxMAA5MjdhYmZhNi0xOWY2LTRhZjEtYTA5ZC1jOTU5ZDlhMWU2NDQ=
+      X-Cache:
+      - CONFIG_NOCACHE
+    status:
+      code: 200
+      message: OK
+- request:
+    body: null
+    headers:
+      Accept:
+      - '*/*'
+      Accept-Encoding:
+      - gzip, deflate
+      Connection:
+      - keep-alive
+      User-Agent:
+      - python-requests/2.28.2
+    method: GET
+    uri: https://planetarycomputer.microsoft.com/api/stac/v1/queryables
+  response:
+    body:
+      string: '{"$schema":"http://json-schema.org/draft-07/schema#","$id":"https://example.org/queryables","type":"object","title":"","properties":{"id":{"title":"Item
+        ID","description":"Item identifier","$ref":"https://schemas.stacspec.org/v1.0.0/item-spec/json-schema/item.json#/definitions/core/allOf/2/properties/id"}}}'
+    headers:
+      Access-Control-Allow-Credentials:
+      - 'true'
+      Access-Control-Allow-Origin:
+      - '*'
+      Content-Length:
+      - '308'
+      Content-Type:
+      - application/schema+json
+      Date:
+      - Wed, 12 Apr 2023 18:25:04 GMT
+      Strict-Transport-Security:
+      - max-age=15724800; includeSubDomains
+      X-Azure-Ref:
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+      X-Cache:
+      - CONFIG_NOCACHE
+    status:
+      code: 200
+      message: OK
+version: 1