handle collection paging differently (#156)

* handle collection paging differently

* test next link

Author: hrodmn

docker-compose.yml

@@ -35,6 +35,8 @@ services:
     build:
       context: .
       dockerfile: Dockerfile.tests
+    volumes:
+      - .:/app
     environment:
       - ENVIRONMENT=local
       - DB_MIN_CONN_SIZE=1

stac_fastapi/pgstac/core.py

@@ -25,6 +25,7 @@
 from stac_fastapi.pgstac.config import Settings
 from stac_fastapi.pgstac.models.links import (
     CollectionLinks,
+    CollectionSearchPagingLinks,
     ItemCollectionLinks,
     ItemLinks,
     PagingLinks,
@@ -90,12 +91,16 @@ async def all_collections(  # noqa: C901
             )
             collections_result: Collections = await conn.fetchval(q, *p)
 
-        next: Optional[str] = None
-        prev: Optional[str] = None
-
+        next: Optional[Dict[str, Any]] = None
+        prev: Optional[Dict[str, Any]] = None
         if links := collections_result.get("links"):
-            next = collections_result["links"].pop("next")
-            prev = collections_result["links"].pop("prev")
+            next = None
+            prev = None
+            for link in links:
+                if link["rel"] == "next":
+                    next = link
+                elif link["rel"] == "prev":
+                    prev = link
 
         linked_collections: List[Collection] = []
         collections = collections_result["collections"]
@@ -120,7 +125,7 @@ async def all_collections(  # noqa: C901
 
                 linked_collections.append(coll)
 
-        links = await PagingLinks(
+        links = await CollectionSearchPagingLinks(
             request=request,
             next=next,
             prev=prev,

stac_fastapi/pgstac/models/links.py

@@ -173,6 +173,60 @@ def link_prev(self) -> Optional[Dict[str, Any]]:
         return None
 
 
+@attr.s
+class CollectionSearchPagingLinks(BaseLinks):
+    next: Optional[Dict[str, Any]] = attr.ib(kw_only=True, default=None)
+    prev: Optional[Dict[str, Any]] = attr.ib(kw_only=True, default=None)
+
+    def link_next(self) -> Optional[Dict[str, Any]]:
+        """Create link for next page."""
+        if self.next is not None:
+            method = self.request.method
+            if method == "GET":
+                # if offset is equal to default value (0), drop it
+                if self.next["body"].get("offset", -1) == 0:
+                    _ = self.next["body"].pop("offset")
+
+                href = merge_params(self.url, self.next["body"])
+
+                # if next link is equal to this link, skip it
+                if href == self.url:
+                    print(self.request.body())
+                    return None
+
+                link = {
+                    "rel": Relations.next.value,
+                    "type": MimeTypes.geojson.value,
+                    "method": method,
+                    "href": href,
+                }
+                return link
+
+        return None
+
+    def link_prev(self):
+        if self.prev is not None:
+            method = self.request.method
+            if method == "GET":
+                # if offset is equal to default value (0), drop it
+                if self.prev["body"].get("offset", -1) == 0:
+                    _ = self.prev["body"].pop("offset")
+
+                href = merge_params(self.url, self.prev["body"])
+
+                # if prev link is equal to this link, skip it
+                if href == self.url:
+                    return None
+                return {
+                    "rel": Relations.previous.value,
+                    "type": MimeTypes.geojson.value,
+                    "method": method,
+                    "href": href,
+                }
+
+        return None
+
+
 @attr.s
 class CollectionLinksBase(BaseLinks):
     """Create inferred links specific to collections."""

tests/resources/test_collection.py

@@ -313,5 +313,15 @@ async def test_get_collections_search_limit_offset(
         "/collections",
         params={"limit": 1},
     )
-    assert len(resp.json()["collections"]) == 1
-    assert resp.json()["collections"][0]["id"] == load_test_collection.id
+    response = resp.json()
+    assert len(response["collections"]) == 1
+    assert response["collections"][0]["id"] == load_test_collection["id"]
+
+    # check next link
+    next_link = [link["href"] for link in response["links"] if link["rel"] == "next"][0]
+    next_url = next_link.replace(str(app_client.base_url), "")
+    next_resp = await app_client.get(next_url)
+    next_response = next_resp.json()
+
+    assert len(next_response["collections"]) == 1
+    assert next_response["collections"][0]["id"] == load_test2_collection.id