CreatePostMutation.js

optimisticUpdater: (proxyStore) => {
  // 1 - create the `newPost` as a mock that can be added to the store
  const id = 'client:newPost:' + tempID++
  const newPost = proxyStore.create(id, 'Post')
  newPost.setValue(id, 'id')
  newPost.setValue(description, 'description')
  newPost.setValue(imageUrl, 'imageUrl')
// 2 - add `newPost` to the store
  const viewerProxy = proxyStore.get(viewerId)
  const connection = ConnectionHandler.getConnection(viewerProxy, 'ListPage_allPosts')
  if (connection) {
    ConnectionHandler.insertEdgeAfter(connection, newPost)
  }
},
updater: (proxyStore) => {
  // 1 - retrieve the `newPost` from the server response
  const createPostField = proxyStore.getRootField('createPost')
  const newPost = createPostField.getLinkedRecord('post')
// 2 - add `newPost` to the store
  const viewerProxy = proxyStore.get(viewerId)
  const connection = ConnectionHandler.getConnection(viewerProxy, 'ListPage_allPosts')
  if (connection) {
    ConnectionHandler.insertEdgeAfter(connection, newPost)
  }
},