React Native & Expo SDK

import { column, Schema, Table } from '@powersync/react-native';

const lists = new Table({
  created_at: column.text,
  name: column.text,
  owner_id: column.text
});

const todos = new Table(
  {
    list_id: column.text,
    created_at: column.text,
    completed_at: column.text,
    description: column.text,
    created_by: column.text,
    completed_by: column.text,
    completed: column.integer
  },
  { indexes: { list: ['list_id'] } }
);

export const AppSchema = new Schema({
  todos,
  lists
});

// For types
export type Database = (typeof AppSchema)['types'];
export type TodoRecord = Database['todos'];
// OR:
// export type Todo = RowType<typeof todos>;
export type ListRecord = Database['lists'];

import { Connector } from './Connector';

export const setupPowerSync = async () => {
  // Uses the backend connector that will be created in the next section
  const connector = new Connector();
  powersync.connect(connector);
};

import { PowerSyncBackendConnector, AbstractPowerSyncDatabase, UpdateType } from "@powersync/react-native"

export class Connector implements PowerSyncBackendConnector {
  /**
  * Implement fetchCredentials to obtain a JWT from your authentication service.
  * See https://docs.powersync.com/configuration/auth/custom
  */
  async fetchCredentials() {
    return {
      // The PowerSync instance URL or self-hosted endpoint
      endpoint: 'https://xxxxxx.powersync.journeyapps.com',
      /**
      * To get started quickly, use a development token, see:
      * Authentication Setup https://docs.powersync.com/configuration/auth/development-tokens) to get up and running quickly
      */
      token: 'An authentication token'
    };
  }

  /**
  * Implement uploadData to send local changes to your backend service.
  * You can omit this method if you only want to sync data from the database to the client
  * See example implementation here:https://docs.powersync.com/client-sdks/reference/react-native-and-expo#3-integrate-with-your-backend
  */
  async uploadData(database: AbstractPowerSyncDatabase) {

    /**
    * For batched crud transactions, use data.getCrudBatch(n);
    * https://powersync-ja.github.io/powersync-js/react-native-sdk/classes/SqliteBucketStorage#getcrudbatch
    */
    const transaction = await database.getNextCrudTransaction();

    if (!transaction) {
      return;
    }

    for (const op of transaction.crud) {
      // The data that needs to be changed in the remote db
      const record = { ...op.opData, id: op.id };
      switch (op.op) {
        case UpdateType.PUT:
          // TODO: Instruct your backend API to CREATE a record
          break;
        case UpdateType.PATCH:
          // TODO: Instruct your backend API to PATCH a record
          break;
        case UpdateType.DELETE:
          //TODO: Instruct your backend API to DELETE a record
          break;
      }
    }

    // Completes the transaction and moves onto the next one
    await transaction.complete();
  }
}

import { Text } from 'react-native';
import { powersync } from "../powersync/system";

export const TodoItemWidget = ({id}) => {
    const [todoItem, setTodoItem] = React.useState([]);
    const [error, setError] = React.useState([]);

    React.useEffect(() => {
        // .get returns the first item of the result. Throws an exception if no result is found.
        powersync.get('SELECT * from todos WHERE id = ?', [id])
          .then(setTodoItem)
          .catch(ex => setError(ex.message))
    }, []);

    return <Text>{error || todoItem.description}</Text>
}

import { FlatList, Text} from 'react-native';
import { powersync } from "../powersync/system";

export const ListsWidget = () => {
    const [lists, setLists] = React.useState([]);

    React.useEffect(() => {
        powersync.getAll('SELECT * from lists').then(setLists)
    }, []);

    return (<FlatList
        data={lists.map(list => ({key: list.id, ...list}))}
        renderItem={({item}) => <Text>{item.name}</Text>}
    />)
}

import { Alert, Button, FlatList, Text, View } from 'react-native';
import { powersync } from "../powersync/system";

export const ListsWidget = () => {
  // Populate lists with one of methods listed above
  const [lists, setLists] = React.useState([]);

  return (
    <View>
      <FlatList
        data={lists.map(list => ({key: list.id, ...list}))}
        renderItem={({item}) => (<View>
          <Text>{item.name}</Text>
           <Button
              title="Delete"
              onPress={async () => {
                  try {
                    await powersync.execute(`DELETE FROM lists WHERE id = ?`, [item.id])
                    // Watched queries should automatically reload after mutation
                  } catch (ex) {
                    Alert('Error', ex.message)
                  }
                }}
            />
        </View>)}
      />
      <Button
        title="Create List"
        color="#841584"
        onPress={async () => {
            try {
              await powersync.execute('INSERT INTO lists (id, created_at, name, owner_id) VALUES (uuid(), datetime(), ?, ?) RETURNING *', [
                'A list name',
                "[The user's uuid]"
              ])
              // Watched queries should automatically reload after mutation
            } catch (ex) {
              Alert.alert('Error', ex.message)
            }
          }}
      />
    </View>
    )
}