Offline Storage

RADFish app users can be out at sea for an extended period of time. They may not have a reliable internet connection. Offline storage lets users to continue using the app to create and manage data while offline.

Storage Models

The @nmfs-radfish/radfishpackage provides two storage methods available LocalStorageMethod and IndexedDBMethod.

LocalStorage

In order to save to LocalStorage, we must provide a unique key that will used to store all of the application data.

import { LocalStorageMethod } from '@nmfs-radfish/radfish';

new LocalStorageMethod(
  "survey-app-storage"
);

IndexedDB

When using IndexedDB, we also need to provide a schema version and model structures. These are used to manage future data migrations.

import { IndexedDBMethod } from '@nmfs-radfish/radfish';

new IndexedDBMethod(
  "survey-app-storage",
  "1.0.0",
  {
    species: "id, name, scientificName",
    catches: "id, speciesId, numberOfFish, weight"
  }
);

React Usage

The @nmfs-radfish/react-radfish package exposes the OfflineStorageWrapper component. This creates a storage model available to that React context.

useOfflineStorage Hooks API

You can then use the useOfflineStorage hook to interact directly with the storage model.

The hook returns an object with these CRUD methods:

• createOfflineData creates a new entry.
• findOfflineData reads data entries.
• updateOfflineData updates data entries.
• deleteOfflineData deletes data entries.

createOfflineData

Creates a new data entry in the storage. Entries will have a unique uuid (String) property to be used for future lookups.

Parameter	Description
tableName	The table the data will be stored in.
data	The data object to create.

Returns: A Promise that resolves of the uuid of the created entry.

findOfflineData

Finds data in the storage based on the given criteria, returns all data if not criteria parameter is passed.

Parameter	Description
tableName	The table to be searched.
criteria	The criteria object to use for finding data, eg {uuid: 123}.

Returns: A Promise that resolves to an array of objects:

updateOfflineData

Updates data in the storage with the matching criteria.

Parameter	Description
tableName	The table to be searched.
criteria	The criteria object to use for finding data, eg {uuid: 123}.

Returns: A Promise that resolves to an array of uuid of the updated entries.

deleteOfflineData

Deletes data in the storage.

Parameter	Description
tableName	The table to be searched.
criteria	The criteria object to use for finding data, eg {uuid: 123}.

Returns: A Promise that resolves to a boolean value of whether the delete operation succeeded without errors.

Usage

Example usage when using IndexedDB:

App.jsx

import React, { useEffect, useState } from "react";
import { Table } from "@nmfs-radfish/react-radfish";
import { useOfflineStorage, OfflineStorageWrapper } from "@nmfs-radfish/react-radfish";

const offlineStorageConfig = {
  type: "indexedDB",
  name: import.meta.env.VITE_INDEXED_DB_NAME,
  version: import.meta.env.VITE_INDEXED_DB_VERSION,
  stores: {
    catches: "++id, numberOfFish"
  },
};

const Catches = () => {
  const { createOfflineData, findOfflineData } = useOfflineStorage();

  let [allCatches, setCatches] = useState([]);

  const fetchCatches = async () => {
    const catches = await findOfflineData("catches");
    setCatches(catches);
  };

  const createNewCatch = async () => {
    await createOfflineData("catches", {
      numberOfFish: Math.floor(Math.random() * 10) + 1,
    });
    await fetchCatches();
  };

  useEffect(() => {
    fetchCatches();
  }, []);

  return (
    <div>
      <button onClick={createNewCatch}>Generate new catch</button>
      <Table 
        data={allCatches} 
        columns={[
          { key: "id", label: "ID" },
          { key: "numberOfFish", label: "Count", sortable: true },
        ]} 
      />
    </div>
  );
};

const App = () => {
  return (
    <OfflineStorageWrapper config={offlineStorageConfig}>
      <Catches />
    </OfflineStorageWrapper>
  );
};

export default App;

Interfacing with backend services

You are free to use any network library of your choice to handle HTTP requests (GET, POST, PUT, DELETE). For your convenience, we’ve provided examples using the native fetch API. You can adapt these examples to the library that best fits your needs.

Refer to the Integrating with Backend Services documentation for examples.