Merge pull request #548 from Vydia/include-cached-data-in-child-error…

…-data

Include cached data with error

Changelog.md

@@ -3,6 +3,7 @@
 Expect active development and potentially significant breaking changes in the `0.x` track. We'll try to be diligent about releasing a `1.0` version in a timely fashion (ideally within 1 or 2 months), so that we can take advantage of SemVer to signify breaking changes from that point on.
 
 ### vNext
+- Pass cached data to the child component along with the error. [PR #548](https://github.com/apollographql/react-apollo/pull/548)
 - Fix version lock down for peer dependency version of React. [PR #626](https://github.com/apollographql/react-apollo/pull/626)
 - Switch `graphql-tag` dependency to `2.0.0`. This isn't really a breaking change because we only export `gql` from `react-apollo`.
 - Fix: convert deprecated `React.PropTypes` to `PropTypes` provided by the `prop-types` package. [PR #628](https://github.com/apollographql/react-apollo/pull/628)

src/graphql.tsx

@@ -571,6 +571,9 @@ export default function graphql(
           if (loading) {
             // while loading, we should use any previous data we have
             assign(data, this.previousData, currentResult.data);
+          } else if (error) {
+            // if there is error, use any previously cached data
+            assign(data, (this.queryObservable.getLastResult() || {}).data);
           } else {
             assign(data, currentResult.data);
             this.previousData = currentResult.data;

test/react-web/client/graphql/queries.test.tsx

@@ -2580,4 +2580,44 @@ describe('queries', () => {
     ]);
   });
 
+  it('passes any cached data when there is a GraphQL error', (done) => {
+    const query = gql`query people { allPeople(first: 1) { people { name } } }`;
+    const data = { allPeople: { people: [ { name: 'Luke Skywalker' } ] } };
+    const networkInterface = mockNetworkInterface(
+      { request: { query }, result: { data } },
+      { request: { query }, error: new Error('No Network Connection') }
+    );
+    const client = new ApolloClient({ networkInterface, addTypename: false });
+
+    let count = 0;
+    @graphql(query, { options: { notifyOnNetworkStatusChange: true } })
+    class Container extends React.Component<any, any> {
+      componentWillReceiveProps = (props) => {
+        switch (count++) {
+          case 0:
+            expect(props.data.allPeople).toEqual(data.allPeople);
+            props.data.refetch();
+            break;
+          case 1:
+            expect(props.data.loading).toBe(true);
+            expect(props.data.allPeople).toEqual(data.allPeople);
+            break;
+          case 2:
+            expect(props.data.loading).toBe(false);
+            expect(props.data.error).toBeTruthy();
+            expect(props.data.allPeople).toEqual(data.allPeople);
+            done();
+            break;
+        }
+      }
+
+      render() {
+        return null;
+      }
+    };
+
+    const wrapper = renderer.create(<ApolloProvider client={client}><Container /></ApolloProvider>);
+  }));
+
+
 });