Fix assignment submission bug on navigation

client/src/components/content-blocks/assignment/Assignment.vue

@@ -91,16 +91,32 @@
 
     methods: {
       _save: debounce(function () {
+        const assignment = this.assignment;
         this.$apollo.mutate({
           mutation: UPDATE_ASSIGNMENT_MUTATION_WITH_SUCCESS,
           variables: {
             input: {
               assignment: {
-                id: this.assignment.id,
+                id: assignment.id,
-                answer: this.assignment.submission.text,
+                answer: assignment.submission.text,
-                document: this.assignment.submission.document,
+                document: assignment.submission.document,
               }
             }
+          },
+          update(store, {data: {updateAssignment: {successful}}}) {
+            try {
+              if (successful) {
+                const query = ASSIGNMENT_QUERY;
+                const variables = {
+                  id: assignment.id
+                };
+                const data = store.readQuery({query, variables});
+                data.assignment = Object.assign({}, assignment);
+                store.writeQuery({query, variables, data});
+              }
+            } catch (e) {
+              // Query did not exist in the cache, and apollo throws a generic Error. Do nothing
+            }
           }
         }).then(() => {
           this.unsaved = false;