Add filter extension

stac_fastapi/api/stac_fastapi/api/config.py

@@ -12,6 +12,7 @@ class ApiExtensions(enum.Enum):
 
     context = "context"
     fields = "fields"
+    filter = "filter"
     query = "query"
     sort = "sort"
     transaction = "transaction"

stac_fastapi/extensions/stac_fastapi/extensions/core/__init__.py

@@ -3,13 +3,15 @@
 
 from .context import ContextExtension
 from .fields import FieldsExtension
+from .filter import FilterExtension
 from .query import QueryExtension
 from .sort import SortExtension
 from .transaction import TransactionExtension
 
 __all__ = (
     "ContextExtension",
     "FieldsExtension",
+    "FilterExtension",
     "QueryExtension",
     "SortExtension",
     "TilesExtension",

stac_fastapi/extensions/stac_fastapi/extensions/core/fields.py

@@ -20,6 +20,7 @@ class FieldsExtension(ApiExtension):
 
     Attributes:
         default_includes (set): defines the default set of included fields.
+        conformance_classes (list): Defines the list of conformance classes for the extension
 
     """
 
@@ -28,17 +29,19 @@ class FieldsExtension(ApiExtension):
     )
     schema_href: Optional[str] = attr.ib(default=None)
     default_includes: Set[str] = attr.ib(
-        default=attr.Factory(
-            lambda: {
-                "id",
-                "type",
-                "geometry",
-                "bbox",
-                "links",
-                "assets",
-                "properties.datetime",
-            }
-        )
+        factory=lambda: {
+            "id",
+            "type",
+            "geometry",
+            "bbox",
+            "links",
+            "assets",
+            "properties.datetime",
+        }
+    )
+
+    conformance_classes: List[str] = attr.ib(
+        default=["https://api.stacspec.org/v1.0.0-beta.2/item-search#fields"]
     )
 
     def register(self, app: FastAPI) -> None:

stac_fastapi/extensions/stac_fastapi/extensions/core/filter.py

@@ -0,0 +1,85 @@
+# encoding: utf-8
+"""Filter Extension."""
+
+from typing import Callable, List, Type, Union
+
+import attr
+from fastapi import APIRouter, FastAPI
+from starlette.responses import JSONResponse, Response
+
+from stac_fastapi.api.models import APIRequest, CollectionUri, EmptyRequest
+from stac_fastapi.api.routes import create_async_endpoint, create_sync_endpoint
+from stac_fastapi.types.core import AsyncBaseFiltersClient, BaseFiltersClient
+from stac_fastapi.types.extension import ApiExtension
+
+
+@attr.s
+class FilterExtension(ApiExtension):
+    """Filter Extension.
+
+    The filter extension adds several endpoints which allow the retrieval of queryables and
+    provides an expressive mechanism for searching based on Item Attributes:
+        GET /queryables
+        GET /collections/{collectionId}/queryables
+
+    https://github.com/radiantearth/stac-api-spec/blob/master/fragments/filter/README.md
+
+    Attributes:
+        client: Queryables endpoint logic
+        conformance_classes: Conformance classes provided by the extension
+
+    """
+
+    client: Union[AsyncBaseFiltersClient, BaseFiltersClient] = attr.ib(
+        factory=BaseFiltersClient
+    )
+    conformance_classes: List[str] = attr.ib(
+        default=[
+            "https://api.stacspec.org/v1.0.0-beta.2/item-search#filter",
+            "https://api.stacspec.org/v1.0.0-beta.2/item-search#filter:simple-cql",
+            "https://api.stacspec.org/v1.0.0-beta.2/item-search#filter:item-search-filter",
+        ]
+    )
+    router: APIRouter = attr.ib(factory=APIRouter)
+    response_class: Type[Response] = attr.ib(default=JSONResponse)
+
+    def _create_endpoint(
+        self,
+        func: Callable,
+        request_type: Union[
+            Type[APIRequest],
+        ],
+    ) -> Callable:
+        """Create a FastAPI endpoint."""
+        if isinstance(self.client, AsyncBaseFiltersClient):
+            return create_async_endpoint(
+                func, request_type, response_class=self.response_class
+            )
+        if isinstance(self.client, BaseFiltersClient):
+            return create_sync_endpoint(
+                func, request_type, response_class=self.response_class
+            )
+        raise NotImplementedError
+
+    def register(self, app: FastAPI) -> None:
+        """Register the extension with a FastAPI application.
+
+        Args:
+            app: target FastAPI application.
+
+        Returns:
+            None
+        """
+        self.router.add_api_route(
+            name="Queryables",
+            path="/queryables",
+            methods=["GET"],
+            endpoint=self._create_endpoint(self.client.get_queryables, EmptyRequest),
+        )
+        self.router.add_api_route(
+            name="Collection Queryables",
+            path="/collections/{collectionId}/queryables",
+            methods=["GET"],
+            endpoint=self._create_endpoint(self.client.get_queryables, CollectionUri),
+        )
+        app.include_router(self.router, tags=["Filter Extension"])

stac_fastapi/sqlalchemy/stac_fastapi/sqlalchemy/core.py

@@ -19,7 +19,6 @@
 from stac_pydantic.links import Relations
 from stac_pydantic.version import STAC_VERSION
 
-from stac_fastapi.extensions.core import ContextExtension, FieldsExtension
 from stac_fastapi.sqlalchemy import serializers
 from stac_fastapi.sqlalchemy.models import database
 from stac_fastapi.sqlalchemy.session import Session
@@ -90,7 +89,7 @@ def item_collection(
                 .order_by(self.item_table.datetime.desc(), self.item_table.id)
             )
             count = None
-            if self.extension_is_enabled(ContextExtension):
+            if self.extension_is_enabled("ContextExtension"):
                 count_query = collection_children.statement.with_only_columns(
                     [func.count()]
                 ).order_by(None)
@@ -136,7 +135,7 @@ def item_collection(
                 )
 
             context_obj = None
-            if self.extension_is_enabled(ContextExtension):
+            if self.extension_is_enabled("ContextExtension"):
                 context_obj = {
                     "returned": len(page),
                     "limit": limit,
@@ -279,7 +278,7 @@ def post_search(
                 )
                 items = query.filter(id_filter).order_by(self.item_table.id)
                 page = get_page(items, per_page=search_request.limit, page=token)
-                if self.extension_is_enabled(ContextExtension):
+                if self.extension_is_enabled("ContextExtension"):
                     count = len(search_request.ids)
                 page.next = (
                     self.insert_token(keyset=page.paging.bookmark_next)
@@ -336,7 +335,7 @@ def post_search(
                         for (op, value) in expr.items():
                             query = query.filter(op.operator(field, value))
 
-                if self.extension_is_enabled(ContextExtension):
+                if self.extension_is_enabled("ContextExtension"):
                     count_query = query.statement.with_only_columns(
                         [func.count()]
                     ).order_by(None)
@@ -379,13 +378,15 @@ def post_search(
                 )
 
             response_features = []
+            filter_kwargs = {}
+
             for item in page:
                 response_features.append(
                     self.item_serializer.db_to_stac(item, base_url=base_url)
                 )
 
             # Use pydantic includes/excludes syntax to implement fields extension
-            if self.extension_is_enabled(FieldsExtension):
+            if self.extension_is_enabled("FieldsExtension"):
                 if search_request.query is not None:
                     query_include: Set[str] = set(
                         [
@@ -409,7 +410,7 @@ def post_search(
                 ]
 
         context_obj = None
-        if self.extension_is_enabled(ContextExtension):
+        if self.extension_is_enabled("ContextExtension"):
             context_obj = {
                 "returned": len(page),
                 "limit": search_request.limit,

stac_fastapi/types/stac_fastapi/types/core.py

@@ -1,7 +1,7 @@
 """Base clients."""
 import abc
 from datetime import datetime
-from typing import Any, Dict, List, Optional, Type, Union
+from typing import Any, Dict, List, Optional, Union
 from urllib.parse import urljoin
 
 import attr
@@ -315,9 +315,25 @@ def conformance_classes(self) -> List[str]:
 
         return list(set(base_conformance_classes))
 
-    def extension_is_enabled(self, extension: Type[ApiExtension]) -> bool:
+    def extension_is_enabled(self, extension: str) -> bool:
         """Check if an api extension is enabled."""
-        return any([isinstance(ext, extension) for ext in self.extensions])
+        return any([type(ext).__name__ == extension for ext in self.extensions])
+
+    def list_conformance_classes(self):
+        """Return a list of conformance classes, including implemented extensions."""
+        base_conformance = [
+            "https://api.stacspec.org/v1.0.0-beta.2/core",
+            "https://api.stacspec.org/v1.0.0-beta.2/item-search",
+            "http://www.opengis.net/spec/ogcapi-features-1/1.0/conf/core",
+            "http://www.opengis.net/spec/ogcapi-features-1/1.0/conf/oas30",
+            "http://www.opengis.net/spec/ogcapi-features-1/1.0/conf/geojson",
+        ]
+
+        for extension in self.extensions:
+            extension_classes = getattr(extension, "conformance_classes", [])
+            base_conformance.extend(extension_classes)
+
+        return base_conformance
 
     def landing_page(self, **kwargs) -> stac_types.LandingPage:
         """Landing page.
@@ -501,9 +517,9 @@ def conformance_classes(self) -> List[str]:
 
         return list(set(conformance_classes))
 
-    def extension_is_enabled(self, extension: Type[ApiExtension]) -> bool:
+    def extension_is_enabled(self, extension: str) -> bool:
         """Check if an api extension is enabled."""
-        return any([isinstance(ext, extension) for ext in self.extensions])
+        return any([type(ext).__name__ == extension for ext in self.extensions])
 
     async def landing_page(self, **kwargs) -> stac_types.LandingPage:
         """Landing page.
@@ -656,3 +672,57 @@ async def item_collection(
             An ItemCollection.
         """
         ...
+
+
+@attr.s
+class AsyncBaseFiltersClient(abc.ABC):
+    """Defines a pattern for implementing the STAC filter extension."""
+
+    async def get_queryables(
+        self, collection_id: Optional[str] = None, **kwargs
+    ) -> Dict[str, Any]:
+        """Get the queryables available for the given collection_id.
+
+        If collection_id is None, returns the intersection of all
+        queryables over all collections.
+
+        This base implementation returns a blank queryable schema. This is not allowed
+        under OGC CQL but it is allowed by the STAC API Filter Extension
+
+        https://github.com/radiantearth/stac-api-spec/tree/master/fragments/filter#queryables
+        """
+        return {
+            "$schema": "https://json-schema.org/draft/2019-09/schema",
+            "$id": "https://example.org/queryables",
+            "type": "object",
+            "title": "Queryables for Example STAC API",
+            "description": "Queryable names for the example STAC API Item Search filter.",
+            "properties": {},
+        }
+
+
+@attr.s
+class BaseFiltersClient(abc.ABC):
+    """Defines a pattern for implementing the STAC filter extension."""
+
+    def get_queryables(
+        self, collection_id: Optional[str] = None, **kwargs
+    ) -> Dict[str, Any]:
+        """Get the queryables available for the given collection_id.
+
+        If collection_id is None, returns the intersection of all
+        queryables over all collections.
+
+        This base implementation returns a blank queryable schema. This is not allowed
+        under OGC CQL but it is allowed by the STAC API Filter Extension
+
+        https://github.com/radiantearth/stac-api-spec/tree/master/fragments/filter#queryables
+        """
+        return {
+            "$schema": "https://json-schema.org/draft/2019-09/schema",
+            "$id": "https://example.org/queryables",
+            "type": "object",
+            "title": "Queryables for Example STAC API",
+            "description": "Queryable names for the example STAC API Item Search filter.",
+            "properties": {},
+        }