教程：React Native 的 Atlas Device Sync

export class Item extends Realm.Object<Item> {
  _id!: BSON.ObjectId;
  isComplete!: boolean;
  summary!: string;
  owner_id!: string;
  priority!: string;
  static schema: Realm.ObjectSchema = {
    name: 'Item',
    primaryKey: '_id',
    properties: {
      // This allows us to automatically generate a unique _id for each Item
      _id: {type: 'objectId', default: () => new BSON.ObjectId()},
      // All todo items will default to incomplete
      isComplete: {type: 'bool', default: false},
      summary: 'string',
      owner_id: 'string',
      priority: {
        // Store the index value of the Priority enum rather than the name
        type: 'int',
        default: Priority.High
      },
    },
  };
}

type Props = {
  onSubmit(args: {summary: string; priority: string;}): void;
};
export function CreateToDoPrompt(props: Props): React.ReactElement<Props> {
  const {onSubmit} = props;
  const [summary, setSummary] = useState('');
  const [priority, setPriority] = useState(Priority.High);
  return (
    <View style={styles.modalWrapper}>
      <Text h4 style={styles.addItemTitle}>
        Add To-Do Item
      </Text>
      <Input
        placeholder="What do you want to do?"
        onChangeText={(text: string) => setSummary(text)}
        autoCompleteType={undefined}
      />
      <Picker
        style={{width: '80%'}}
        selectedValue={priority}
        onValueChange={value => setPriority(value)}>
        {Priority.map(priority  => (
          <Picker.Item
            key={priority}
            label={priority}
            value={Priority[priority]}
           />
        ))}
      </Picker>
      <Button
        title="Save"
        buttonStyle={styles.saveButton}
        onPress={() => onSubmit({summary, priority})}
      />
    </View>
  );
}

const createItem = useCallback(
  ({summary, priority}: {summary: string, priority: string}) => {
    realm.write(() => {
      return new Item(realm, {
        summary,
        owner_id: user?.id,
        priority
      });
    });
  },
  [realm, user],
);

<CreateToDoPrompt
  onSubmit={({summary, priority}) => {
    setShowNewItemOverlay(false);
    createItem({summary, priority});
  }}
/>

<ListItem
  key={`${item._id}`}
  bottomDivider
  topDivider
  hasTVPreferredFocus={undefined}
  tvParallaxProperties={undefined}>
  <Text>{item.priority}</Text>
  <ListItem.Title style={styles.itemTitle}>
    {item.summary}
  </ListItem.Title>
  <ListItem.Subtitle style={styles.itemSubtitle}>
    {item.owner_id === user?.id ? '(mine)' : ''}
  </ListItem.Subtitle>
  <ListItem.CheckBox
    checked={item.isComplete}
    checkedColor={COLORS.primary}
    iconType="material"
    checkedIcon="check-box"
    uncheckedIcon="check-box-outline-blank"
    onPress={() => toggleItemIsComplete(item._id)}
  />
  <Button
    type="clear"
    onPress={() => deleteItem(item._id)}
    icon={
      <Icon
        type="material"
        name="clear"
        size={12}
        color="#979797"
        tvParallaxProperties={undefined}
      />
    }
  />
</ListItem>

const [showImportantOnly, setShowImportantOnly] = useState(false);

<Button
  title={showImportantOnly ? 'Show All' : 'Show Important Only'}
  buttonStyle={{
    ...styles.addToDoButton,
    backgroundColor: showImportantOnly ? '#00A35C' : '#FFC010',
  }}
  onPress={() => setShowImportantOnly(showImportantOnly => !showImportantOnly)}
/>

useEffect(() => {
  if (showAllItems) {
    realm.subscriptions.update(mutableSubs => {
      mutableSubs.removeByName(ownItemsSubscriptionName);
      mutableSubs.add(realm.objects(Item), {name: itemSubscriptionName});
    });
  } else if (showImportantOnly) {
    realm.subscriptions.update(mutableSubs => {
      mutableSubs.removeByName(itemSubscriptionName);
      mutableSubs.add(
        realm.objects(Item).filtered(`owner_id == "${user?.id}" && priority <= 1`),
        {name: ownItemsSubscriptionName},
      );
    });
  } else {
    realm.subscriptions.update(mutableSubs => {
      mutableSubs.removeByName(itemSubscriptionName);
      mutableSubs.add(
        realm.objects(Item).filtered(`owner_id == "${user?.id}"`),
        {name: ownItemsSubscriptionName},
      );
    });
  }
}, [realm, user, showAllItems, showImportantOnly]);