react-apollo-cache-example-3.js

  const onUpdate = (key) => (value) => {
    const task = { [key]: value };
    updateTask({
      variables: { task, id },
      update: (proxy, { data = {} }) => {
        // update cache with local values
        proxy.writeData({ id: `Task:${id}`, data: task });

        // or update cache with the values coming from the server,
        // for example if you need to reflect the updated timestamp
        const { updateTask } = data;
        proxy.writeData({ id: `Task:${id}`, data: updateTask });
      },
    });
  };