allow querying connection metadata and then subsequent data in relayStylePagination

src/cache/inmemory/__tests__/__snapshots__/policies.ts.snap

@@ -765,3 +765,68 @@ Object {
   },
 }
 `;
+
+exports[`type policies field policies can handle Relay-style pagination without args 1`] = `
+Object {
+  "ROOT_QUERY": Object {
+    "__typename": "Query",
+    "todos": Object {
+      "edges": Array [
+        Object {
+          "__typename": "TodoEdge",
+          "cursor": "YXJyYXljb25uZWN0aW9uOjI=",
+          "node": Object {
+            "__ref": "Todo:1",
+          },
+        },
+      ],
+      "pageInfo": Object {
+        "__typename": "PageInfo",
+        "endCursor": "YXJyYXljb25uZWN0aW9uOjI=",
+        "hasNextPage": true,
+        "hasPreviousPage": false,
+        "startCursor": "YXJyYXljb25uZWN0aW9uOjI=",
+      },
+      "totalCount": 1292,
+    },
+  },
+  "Todo:1": Object {
+    "__typename": "Todo",
+    "id": "1",
+    "title": "Fix the tests",
+  },
+}
+`;
+
+exports[`type policies field policies can handle Relay-style pagination without args 2`] = `
+Object {
+  "ROOT_QUERY": Object {
+    "__typename": "Query",
+    "todos": Object {
+      "edges": Array [
+        Object {
+          "__typename": "TodoEdge",
+          "cursor": "YXJyYXljb25uZWN0aW9uOjI=",
+          "node": Object {
+            "__ref": "Todo:1",
+          },
+        },
+      ],
+      "extraMetaData": "extra",
+      "pageInfo": Object {
+        "__typename": "PageInfo",
+        "endCursor": "YXJyYXljb25uZWN0aW9uOjI=",
+        "hasNextPage": true,
+        "hasPreviousPage": false,
+        "startCursor": "YXJyYXljb25uZWN0aW9uOjI=",
+      },
+      "totalCount": 1293,
+    },
+  },
+  "Todo:1": Object {
+    "__typename": "Todo",
+    "id": "1",
+    "title": "Fix the tests",
+  },
+}
+`;

src/cache/inmemory/__tests__/policies.ts

@@ -2177,6 +2177,182 @@ describe("type policies", function () {
       });
     });
 
+    itAsync("can handle Relay-style pagination without args", (resolve, reject) => {
+      const cache = new InMemoryCache({
+        addTypename: false,
+        typePolicies: {
+          Query: {
+            fields: {
+              todos: relayStylePagination(),
+            },
+          },
+        },
+      });
+
+      const firstQuery = gql`
+        query TodoQuery {
+          todos {
+            totalCount
+          }
+        }
+      `
+
+      const secondQuery = gql`
+        query TodoQuery {
+          todos(after: $after, first: $first) {
+            pageInfo {
+              __typename
+              hasNextPage
+              endCursor
+            }
+            totalCount
+            edges {
+              __typename
+              node {
+                __typename
+                id
+                title
+              }
+            }
+          }
+        }
+      `
+
+      const thirdQuery = gql`
+        query TodoQuery {
+          todos {
+            totalCount
+            extraMetaData
+          }
+        }
+      `
+
+      const secondVariables = {
+        first: 1,
+      };
+
+      const secondEdges = [
+        {
+          __typename: "TodoEdge",
+          node: {
+            __typename: "Todo",
+            id: '1',
+            title: 'Fix the tests'
+          }
+        },
+      ];
+
+      const secondPageInfo = {
+        __typename: "PageInfo",
+        endCursor: "YXJyYXljb25uZWN0aW9uOjI=",
+        hasNextPage: true,
+      };
+
+      const link = new MockLink([
+        {
+          request: {
+            query: firstQuery,
+          },
+          result: {
+            data: {
+              todos: {
+                totalCount: 1292
+              }
+            }
+          }
+        },
+        {
+          request: {
+            query: secondQuery,
+            variables: secondVariables,
+          },
+          result: {
+            data: {
+              todos: {
+                edges: secondEdges,
+                pageInfo: secondPageInfo,
+                totalCount: 1292,
+              }
+            }
+          },
+        },
+        {
+          request: {
+            query: thirdQuery,
+          },
+          result: {
+            data: {
+              todos: {
+                totalCount: 1293,
+                extraMetaData: 'extra',
+              }
+            }
+          },
+        }
+      ]).setOnError(reject);
+
+      const client = new ApolloClient({ link, cache });
+
+      client.query({query: firstQuery}).then(result => {
+        expect(result).toEqual({
+          loading: false,
+          networkStatus: NetworkStatus.ready,
+          data: {
+            todos: {
+              totalCount: 1292
+            }
+          }
+        })
+
+        expect(cache.extract()).toEqual({
+          ROOT_QUERY: {
+            __typename: "Query",
+            todos: {
+              edges: [],
+              pageInfo: {
+                "endCursor": "",
+                "hasNextPage": true,
+                "hasPreviousPage": false,
+                "startCursor": "",
+               },
+               totalCount: 1292
+             },
+          }
+        });
+
+        client.query({query: secondQuery, variables: secondVariables}).then(result => {
+          expect(result).toEqual({
+            loading: false,
+            networkStatus: NetworkStatus.ready,
+            data: {
+              todos: {
+                edges: secondEdges,
+                pageInfo: secondPageInfo,
+                totalCount: 1292,
+              }
+            }
+          })
+
+          expect(cache.extract()).toMatchSnapshot()
+
+          client.query({query: thirdQuery}).then(result => {
+            expect(result).toEqual({
+              loading: false,
+              networkStatus: NetworkStatus.ready,
+              data: {
+                todos: {
+                  totalCount: 1293,
+                  extraMetaData: 'extra',
+                }
+              }
+            })
+            expect(cache.extract()).toMatchSnapshot()
+            resolve()
+          })
+        })
+      })
+    })
+
     itAsync("can handle Relay-style pagination", (resolve, reject) => {
       const cache = new InMemoryCache({
         addTypename: false,

src/utilities/policies/pagination.ts

@@ -57,7 +57,7 @@ type TInternalRelay<TNode> = Readonly<{
 // anything about connections, edges, cursors, or pageInfo objects.
 export function relayStylePagination<TNode = Reference>(
   keyArgs: KeyArgs = false,
-): FieldPolicy<TInternalRelay<TNode>> {
+): FieldPolicy<TInternalRelay<TNode>, Partial<TInternalRelay<TNode>>> {
   return {
     keyArgs,
 
@@ -79,9 +79,7 @@ export function relayStylePagination<TNode = Reference>(
     },
 
     merge(existing = makeEmptyData(), incoming, { args }) {
-      if (!args) return existing; // TODO Maybe throw?
-
-      const incomingEdges = incoming.edges.slice(0);
+      const incomingEdges = incoming.edges ? incoming.edges.slice(0) : [];
       if (incoming.pageInfo) {
         updateCursor(incomingEdges, 0, incoming.pageInfo.startCursor);
         updateCursor(incomingEdges, -1, incoming.pageInfo.endCursor);
@@ -90,17 +88,17 @@ export function relayStylePagination<TNode = Reference>(
       let prefix = existing.edges;
       let suffix: typeof prefix = [];
 
-      if (args.after) {
+      if (args && args.after) {
         const index = prefix.findIndex(edge => edge.cursor === args.after);
         if (index >= 0) {
           prefix = prefix.slice(0, index + 1);
           // suffix = []; // already true
         }
-      } else if (args.before) {
+      } else if (args && args.before) {
         const index = prefix.findIndex(edge => edge.cursor === args.before);
         suffix = index < 0 ? prefix : prefix.slice(index);
         prefix = [];
-      } else {
+      } else if (incoming.edges) {
         // If we have neither args.after nor args.before, the incoming
         // edges cannot be spliced into the existing edges, so they must
         // replace the existing edges. See #6592 for a motivating example.
@@ -114,14 +112,14 @@ export function relayStylePagination<TNode = Reference>(
       ];
 
       const pageInfo = {
-        ...incoming.pageInfo,
+        ...(incoming.pageInfo || {}),
         ...existing.pageInfo,
         startCursor: cursorFromEdge(edges, 0),
         endCursor: cursorFromEdge(edges, -1),
       };
 
       const updatePageInfo = (name: keyof TInternalRelay<TNode>["pageInfo"]) => {
-        const value = incoming.pageInfo[name];
+        const value = incoming.pageInfo && incoming.pageInfo[name];
         if (value !== void 0) {
           (pageInfo as any)[name] = value;
         }