1 files changed, 79 insertions, 1 deletions

diff --git a/app/assets/javascripts/graphql_shared/issuable_client.js b/app/assets/javascripts/graphql_shared/issuable_client.js
index 01cc2fc3018..316bc746051 100644
--- a/app/assets/javascripts/graphql_shared/issuable_client.js
+++ b/app/assets/javascripts/graphql_shared/issuable_client.js
@@ -6,6 +6,8 @@ import getIssueStateQuery from '~/issues/show/queries/get_issue_state.query.grap
 import createDefaultClient from '~/lib/graphql';
 import typeDefs from '~/work_items/graphql/typedefs.graphql';
 import { WIDGET_TYPE_NOTES } from '~/work_items/constants';
+import getWorkItemLinksQuery from '~/work_items/graphql/work_item_links.query.graphql';
+import { findHierarchyWidgetChildren } from '~/work_items/utils';
 
 export const config = {
   typeDefs,
@@ -13,7 +15,9 @@ export const config = {
     // included temporarily until Vuex is removed from boards app
     dataIdFromObject: (object) => {
       // eslint-disable-next-line no-underscore-dangle
-      return object.__typename === 'BoardList' ? object.iid : defaultDataIdFromObject(object);
+      return object.__typename === 'BoardList' && !window.gon?.features?.apolloBoards
+        ? object.iid
+        : defaultDataIdFromObject(object);
     },
     typePolicies: {
       Project: {
@@ -72,6 +76,7 @@ export const config = {
                     },
                   };
                 }
+
                 return incomingWidget || existingWidget;
               });
             },
@@ -83,12 +88,85 @@ export const config = {
           nodes: concatPagination(),
         },
       },
+      ...(window.gon?.features?.apolloBoards
+        ? {
+            BoardList: {
+              fields: {
+                issues: {
+                  keyArgs: ['filters'],
+                },
+              },
+            },
+            IssueConnection: {
+              merge(existing = { nodes: [] }, incoming, { args }) {
+                if (!args.after) {
+                  return incoming;
+                }
+                return {
+                  ...incoming,
+                  nodes: [...existing.nodes, ...incoming.nodes],
+                };
+              },
+            },
+            EpicList: {
+              fields: {
+                epics: {
+                  keyArgs: ['filters'],
+                },
+              },
+            },
+            EpicConnection: {
+              merge(existing = { nodes: [] }, incoming, { args }) {
+                if (!args.after) {
+                  return incoming;
+                }
+                return {
+                  ...incoming,
+                  nodes: [...existing.nodes, ...incoming.nodes],
+                };
+              },
+            },
+            BoardEpicConnection: {
+              merge(existing = { nodes: [] }, incoming, { args }) {
+                if (!args.after) {
+                  return incoming;
+                }
+                return {
+                  ...incoming,
+                  nodes: [...existing.nodes, ...incoming.nodes],
+                };
+              },
+            },
+          }
+        : {}),
     },
   },
 };
 
 export const resolvers = {
   Mutation: {
+    addHierarchyChild: (_, { id, workItem }, { cache }) => {
+      const queryArgs = { query: getWorkItemLinksQuery, variables: { id } };
+      const sourceData = cache.readQuery(queryArgs);
+
+      const data = produce(sourceData, (draftState) => {
+        findHierarchyWidgetChildren(draftState.workItem).push(workItem);
+      });
+
+      cache.writeQuery({ ...queryArgs, data });
+    },
+    removeHierarchyChild: (_, { id, workItem }, { cache }) => {
+      const queryArgs = { query: getWorkItemLinksQuery, variables: { id } };
+      const sourceData = cache.readQuery(queryArgs);
+
+      const data = produce(sourceData, (draftState) => {
+        const hierarchyChildren = findHierarchyWidgetChildren(draftState.workItem);
+        const index = hierarchyChildren.findIndex((child) => child.id === workItem.id);
+        hierarchyChildren.splice(index, 1);
+      });
+
+      cache.writeQuery({ ...queryArgs, data });
+    },
     updateIssueState: (_, { issueType = undefined, isDirty = false }, { cache }) => {
       const sourceData = cache.readQuery({ query: getIssueStateQuery });
       const data = produce(sourceData, (draftData) => {