Data Replication in SignalDB

For seamless integration of your app with remote services, SignalDB offers robust data replication capabilities. Whether you're building a local app or sharing data across multiple clients, SignalDB's modular replication system ensures efficient data synchronization.

Central to SignalDB's replication functionality is the ReplicatedCollection class. This specialized class streamlines the replication process, allowing you to effortlessly replicate data to any remote service.

The usage of the ReplicatedCollection is really simple:

const Todos = new ReplicatedCollection({
  pull: async () => {
    // The pull method is for fetching data from the remote service
    // similar to the persistence adapters, you have two options to return the fetched data

    // You can return the data directly
    // return { items: [...] }

    // Or you can return only the changes
    // return { changes: { added: [...], modified: [...], removed: [...] } }
  },
  push: async (changes, items) => {
    // The push method is called when the local data has changed
    // As the first parameter you get the changes in the format { added: [...], modified: [...], removed: [...] }
    // As the second parameter you also get all items in the collection, if you need them
    // in the push method, no return value is expected
  },
  registerRemoteChange: async (onChange) => {
    // The registerRemoteChange method is for registering a callback that is called when the remote data has changed
    // The callback takes no parameters. After you called the onChange callback, the pull method is called
  },

  // You can also optionally specify a persistence adapter
  // If a persistence adapter is used, the data is loaded first and will be updated after the server data is fetched
  // If the data will be updated, the data will be saved to the persistence adapter and pushed to the server simultaneously
  persistence: createLocalStorageAdapter('todos'),
})