React Native：Promise.reject 消息在用户单击按钮时不显示

Question

所以这是我的应用程序流程：

用户登录后，他们可以单击打开CustomDrawer堆栈的汉堡包堆栈，然后单击label: "EVENTS" 。 这会将用户重定向到AvailableEvents组件：

export class AvailableEvents extends PureComponent {
  static propTypes = {
    availableEvents: PropTypes.array,
    displayFooter: PropTypes.bool,
    fetchEvents: PropTypes.func,
    loading: PropTypes.bool,
    navigation: PropTypes.object,
    setSelectedEvent: PropTypes.func,
    userState: PropTypes.string
  };

  constructor(props) {
    super(props);
    this.state = {
      refreshing: false,
      appState: AppState.currentState
    };
  }

  async componentDidMount() {
    AppState.addEventListener("change", this._handleAppStateChange);
    const doRefresh = await shouldRefresh("events");
    if (this.props.availableEvents.length === 0 || doRefresh) {
      this.props.fetchEvents();
    }
  }

  componentWillUnmount() {
    AppState.removeEventListener("change", this._handleAppStateChange);
  }

  _handleAppStateChange = async appState => {
    if (
      this.state.appState.match(/inactive|background/) &&
      appState === "active"
    ) {
      const doRefresh = await shouldRefresh("events");
      if (doRefresh) {
        this.props.fetchEvents();
      }
    }
    this.setState({ appState });
  };

  _goto = event => {
    this.props.setSelectedEvent(event);
    console.log(this.props.setSelectedEvent(event));
    const title = `${event.LegislatureType} Event`;
    this.props.navigation.navigate("EventDetails", { title });
  };

  _keyExtractor = item => item.Key;

  _renderEvent = ({ item }) => {
    return (
      <EventFeedCard
        style={listStyles.push}
        mainActionButtonPress={() => this._goto(item)}
        event={item}
      />
    );
  };

  _onRefresh = async () => {
    try {
      this.setState({ refreshing: true });
      this.props
        .fetchEvents()
        .then(() => {
          this.setState({ refreshing: false });
        })
        .catch(() => {
          this.setState({ refreshing: false });
        });
    } catch (e) {
      this.setState({ refreshing: false });
    }
  };
  // when clicking EVENTS from CustomDrawer it loads from here
  render() {
    if (this.props.loading && !this.state.refreshing) {
      console.log(
        "Loading from AvailableEvents: ",
        this.props.loading && !this.state.refreshing
      );
      return <Loading />;
    }

这是EventFeedCard的父组件：

const EventFeedCard = props => {
  //prettier-ignore
  const source = props.event.ImageURL ? {uri: props.event.ImageURL} : defaultImage;
  //prettier-ignore
  const contentStyles = deviceHelpers.isTablet ? feedContentStyles.tabletContent : feedContentStyles.content;
  //prettier-ignore
  const contentFlexer = deviceHelpers.isTablet ? {flex: 2} : {flex: 1};
  //prettier-ignore
  const eventLocation = `${props.event.Location.City}, ${props.event.Location.StateAbbreviation}`;
  const displayTotal = props.isRegistered && !props.event.IsFree;

  return (
    <Card style={props.style}>
      <View style={feedContentStyles.header}>
        <Text style={feedContentStyles.title}>
          {`NFIB ${props.event.LegislatureType.toUpperCase()} EVENT`}
        </Text>
        <Text style={feedContentStyles.postDate}>
          {`On ${format(props.event.StartDate, "MMM D, YYYY")}`}
        </Text>
      </View>
      {!deviceHelpers.isTablet && (
        <View style={feedContentStyles.feedMainImageContainer}>
          <Image source={source} style={feedContentStyles.feedMainImage} />
        </View>
      )}
      <Divider />
      <View style={contentStyles}>
        {deviceHelpers.isTablet && (
          <View style={feedContentStyles.feedMainImageContainerTablet}>
            <Image source={source} style={feedContentStyles.feedMainImage} />
          </View>
        )}
        <View style={contentFlexer}>
          <Text style={feedContentStyles.contentTitle}>
            {props.event.Title}
          </Text>
          <View style={[styles.detailsRow, { marginBottom: 8 }]}>
            <Icon
              name="date-range"
              size={16}
              color="rgba(0,0,0,0.5)"
              style={styles.icon}
            />
            <EventDate event={props.event} />
          </View>
          <View style={[styles.detailsRow, { marginBottom: 8 }]}>
            <Icon
              name="location-on"
              size={16}
              color="rgba(0,0,0,0.5)"
              style={styles.icon}
            />
            <Text style={styles.smallerText}>{eventLocation}</Text>
          </View>
          {displayTotal && (
            <View style={[styles.detailsRow, { marginBottom: 8 }]}>
              <Icon
                name="credit-card"
                size={16}
                color="rgba(0,0,0,0.54)"
                style={styles.icon}
              />
              <Text style={styles.smallerText}>{`$${props.grandTotal}`}</Text>
            </View>
          )}
          <Text style={feedContentStyles.parragraph}>
            {props.event.ShortDescription}
          </Text>
        </View>
      </View>
      {props.isRegistered && <Divider style={styles.dividerPusher} />}
      <View style={[feedContentStyles.footerActions, styles.footerActions]}>
        {
          props.isRegistered
          /* && (
          <TouchableOpacity
            style={styles.calendarBtn}
            onPress={props.handleAddToCalendar}
          >
            <Text style={styles.gothamBold14Black}>{"ADD TO CALENDAR"}</Text>
          </TouchableOpacity>
        ) */
        }
        <TextButton
          color={v2Colors.green}
          title={"VIEW DETAILS"}
          titleColor={v2Colors.white}
          onPress={props.mainActionButtonPress}
          titleStyle={v2ButtonStyles.titleStyle}
        />
      </View>
    </Card>
  );
};

EventFeedCard是Details组件的父组件：

export class Details extends Component {
  static propTypes = {
    auth: PropTypes.object,
    checkingUserMembership: PropTypes.bool,
    checkUserMembership: PropTypes.func,
    fetchSelectedEvent: PropTypes.func,
    isLapsedMember: PropTypes.bool,
    isMember: PropTypes.bool,
    loadingSelectedEvent: PropTypes.bool,
    navigation: PropTypes.object,
    primaryIndividual: PropTypes.object,
    selectedEvent: PropTypes.object,
    selectedPrice: PropTypes.object,
    setSelectedPrice: PropTypes.func,
    userKey: PropTypes.string,
    userOrganization: PropTypes.object
  };

  static navigationOptions = ({ navigation }) => ({
    title: navigation.state.params.title
  });

  constructor(props) {
    super(props);
    const prices = getDetailPrices(this.props);
    this.state = {
      userOpenedMemberLink: false,
      appState: AppState.currentState,
      ...prices
    };
  }

  componentDidMount() {
    this.props.fetchSelectedEvent();
    this.props.checkUserMembership();
    AppState.addEventListener("change", this._handleAppStateChange);

    if (this.props.isMember && !this.props.isLapsedMember) {
      this._selectMemberPrice();
    }
  }

  componentWillUnmount() {
    AppState.removeEventListener("change", this._handleAppStateChange);
  }

  _selectMemberPrice = () => {
    const price = this.state.individualPrices.find(p => p.IsMemberPrice);
    if (price) {
      this.props.setSelectedPrice(price);
    }
  };

  _handleAppStateChange = async appState => {
    if (
      this.state.appState.match(/inactive|background/) &&
      appState === "active"
    ) {
      this.props.checkUserMembership();
    }
  };

  _validateCapacity = selectedEvent => {
    if (selectedEvent.NumberOfSeatsAvailable === 0) {
      Alert.alert(
        "Capacity Exceeded",
        capacityLimit,
        [
          {
            text: "OK",
            onPress: () => false,
            style: "cancel"
          }
        ],
        { cancelable: false }
      );

      return false;
    }

    return true;
  };

  _alertNoTableSeats = () => {
    Alert.alert(
      "Capacity Exceeded",
      capacityLimitTable,
      [
        {
          text: "OK",
          onPress: () => false,
          style: "cancel"
        }
      ],
      { cancelable: false }
    );
  };

  _navigate = () => {
    const {
      selectedEvent,
      isMember,
      selectedPrice,
      isLapsedMember
    } = this.props;
    const hasSeats = this._validateCapacity(selectedEvent);
    console.log("Validating Seating Capacity to be: ", hasSeats);

    if (hasSeats) {
      if (selectedEvent.IsFree) {
        //eslint-disable-next-line
        if (selectedEvent.IsMembersOnly && (!isMember || isLapsedMember)) {
          this._alertMembershipIssue();
        } else {
          this.props.navigation.navigate("EventRegistration");
        }
      } else if (selectedPrice) {
        //eslint-disable-next-line
        this.props.navigation.navigate("EventRegistration");
      } else {
        Alert.alert(
          "Event Pricing",
          "Please select a price before continuing.",
          [
            {
              text: "OK",
              onPress: () => false,
              style: "cancel"
            }
          ],
          { cancelable: false }
        );
      }
    }
  };

  _loginAsMember = (price = null) => {
    this.props.navigation.navigate("MembershipConfirmation", { price });
  };

  _canSelectPrice = price => {
    if (price.IsMemberPrice && this.props.isLapsedMember) {
      return false;
    }

    if (!this.props.isMember && price.IsMemberPrice) {
      return false;
    }

    return true;
  };

  _tableSeatsAvailable = price => {
    if (
      price.IsTable &&
      this.props.selectedEvent.NumberOfSeatsAvailable < price.NumberOfSeats
    ) {
      return false;
    }
    return true;
  };

  _selectPrice = async price => {
    const canSelect = this._canSelectPrice(price);
    if (canSelect) {
      const tableSeatsAvailable = this._tableSeatsAvailable(price);
      if (tableSeatsAvailable) {
        this.props.setSelectedPrice(price);
      } else {
        this._alertNoTableSeats();
      }
    } else {
      this._alertMembershipIssue(price);
    }
  };

  _alertMembershipIssue = (price = null) => {
    const { isLapsedMember, userKey } = this.props;
    const buttons = [
      {
        text: isLapsedMember ? "Renew Membership" : "Join NFIB",
        onPress: () => {
          let url = `${env.membershipJoinLink}=${userKey}`;
          if (isLapsedMember) {
            const { userOrganization, primaryIndividual } = this.props;
            const { PostalCode: zip } = userOrganization.Addresses[0];
            const lastName = primaryIndividual.PersonalDetails.LastName;
            const memberID = userOrganization.Id;
            //prettier-ignore
            url = `${env.membershipRenewLink}?lname=${lastName}&mid=${memberID}&zip=${zip}`;
          }
          Linking.openURL(url);
          this.setState({ userOpenedMemberLink: true });
        }
      },
      {
        text: "Cancel",
        onPress: () => false,
        style: "cancel"
      }
    ];

    if (!isLapsedMember) {
      buttons.unshift({
        text: "I am a Member",
        onPress: () => this._loginAsMember(price)
      });
    }

    Alert.alert(
      isLapsedMember ? "Renew Membership" : "Members Only",
      memberMsg,
      buttons,
      { cancelable: false }
    );
  };
  // clicking on VIEW DETAILS from EventFeedCard component fires off this if conditional
  render() {
    if (this.props.loadingSelectedEvent) {
      console.log(
        "Loading from Details component: ",
        this.props.loadingSelectedEvent
      );
      return <Loading />;
    }

    return (
      <EventDetails
        event={this.props.selectedEvent}
        handleRegistrationButtonPress={this._navigate}
        handleSelectPrice={this._selectPrice}
        tablePrices={this.state.tablePrices}
        individualPrices={this.state.individualPrices}
        selectedPrice={this.props.selectedPrice}
        checkingUserMembership={this.props.checkingUserMembership}
      />
    );
  }
}

单击EventDetails组件中的REGISTER FOR EVENTS ，该组件是EventFeedCard and Details 的子组件：

const EventDetails = props => {
  return (
    <SafeAreaView style={styles.container}>
      <ScrollView contentContainerStyle={styles.list}>
        <EventMainDetails event={props.event} displayRemainingSeats={true} />
        <View style={styles.cardsContainer}>
          {!deviceHelpers.isTablet && <PhoneEventDescription {...props} />}
          {deviceHelpers.isTablet && <TabletEventDescription {...props} />}
          {props.event.IsRestricted && (
            <Text style={styles.restrictedText}>{restrictedText}</Text>
          )}
        </View>
      </ScrollView>
      {!props.event.IsRestricted && (
        <TouchableOpacity
          style={[styles.footer, styles.rowFooter]}
          onPress={props.handleRegistrationButtonPress}
        >
          {props.checkingUserMembership ? (
            {
              /* <ActivityIndicator /> */
            }
          ) : (
            <Text style={styles.footerBtnText}>
              {"HOWDY! REGISTER FOR EVENT"}
            </Text>
          )}
        </TouchableOpacity>
      )}
    </SafeAreaView>
  );
};

触发重定向到EventRegistrationForm ：

const EventRegistrationForm = ({
  badgeNameError,
  currentUser,
  displayGuestErrors,
  event,
  eventBadgeName,
  grandTotal,
  guestUsers,
  handleAddGuestButtonPress,
  handleBadgeNameInputChange,
  handleGuestFirstNameChange,
  handleGuestLastNameChange,
  handlePaymentsButtonPress,
  handleRemoveGuestButtonPress,
  selectedPrice,
  userOrganization,
}) => {
  const displayPersonal = event.IsFree || !selectedPrice.IsTable;
  const roomForGuests =
    (event.NumberOfSeatsAvailable || 0) > guestUsers.length + 1;
  const displayAddButton =
    (event.IsFree || roomForGuests) && !(selectedPrice || {}).IsTable;

  return (
    <SafeAreaView style={styles.container}>
      <KeyboardAwareScrollView
        contentContainerStyle={{paddingBottom: 121}}
        showsVerticalScrollIndicator={false}
        keyboardShouldPersistTaps={'handled'}
        enableOnAndroid={true}
        extraHeight={90}
      >
        <EventMainDetails
          event={event}
          currentUser={currentUser}
          displayRemainingSeats={true}
        />
        <View style={styles.cardsContainer}>
          {selectedPrice &&
            selectedPrice.IsTable && (
              <Card style={styles.tablePriceCard} tappable={false}>
                <Text style={styles.contentTitle}>
                  {selectedPrice.TableName}
                </Text>
                <Text style={styles.contentTitle}>
                  {`$${selectedPrice.Price}`}
                </Text>
              </Card>
            )}
          {displayPersonal && (
            <EventRegistrationFormPersonalDetails
              handleBadgeNameInputChange={handleBadgeNameInputChange}
              eventBadgeName={eventBadgeName}
              currentUser={currentUser}
              eventPrice={selectedPrice && selectedPrice.Price}
              userOrganization={
                userOrganization && userOrganization.OrganizationDetails.Name
              }
              badgeNameError={badgeNameError}
            />
          )}
          <EventRegistrationGuestForm
            handleGuestLastNameChange={handleGuestLastNameChange}
            handleGuestFirstNameChange={handleGuestFirstNameChange}
            guestUsers={guestUsers}
            handleRemoveGuestButtonPress={handleRemoveGuestButtonPress}
            isTableGuest={selectedPrice && selectedPrice.IsTable}
            displayGuestErrors={displayGuestErrors}
          />
          {!displayAddButton &&
            !selectedPrice.IsTable && (
              <Text>
                {
                  'You cannot add more guests to this event. If you have questions, please contact NFIB by calling the number provided in the event details or 1-800-NFIB-NOW.'
                }
              </Text>
            )}
          {displayAddButton && (
            <View style={guestbtnStyle}>
              <TextButton
                title={'ADD A GUEST'}
                color={v2Colors.green}
                titleColor={v2Colors.white}
                onPress={handleAddGuestButtonPress}
                titleStyle={v2ButtonStyles.titleStyle}
              />
            </View>
          )}
        </View>
      </KeyboardAwareScrollView>
      <View style={styles.footer}>
        {!event.IsFree && (
          <View style={styles.eventTotal}>
            <Text style={styles.totalText}>{'Total'}</Text>
            <Text style={[styles.totalText, {fontWeight: 'bold'}]}>
              {`$${grandTotal}`}
            </Text>
          </View>
        )}
        <TouchableOpacity
          style={styles.rowFooter}
          onPress={handlePaymentsButtonPress}
        >
          {event.IsFree && (
            <Text style={styles.footerBtnText}>{'REGISTER FOR EVENT'}</Text>
          )}
          {!event.IsFree && (
            <Text style={styles.footerBtnText}>{'CONTINUE TO PAYMENT'}</Text>
          )}
        </TouchableOpacity>
      </View>
    </SafeAreaView>
  );
};

当用户单击REGISTER FOR EVENT一次时，它会从events/helpers/action-helpers触发saveRegistration async function ：

export async function saveRegistration(
      { selectedEvent, registrationsData, paymentsData },
      user
    ) {
      try {
        const numberOfSeats = getNumberOfSeats(registrationsData);
        console.log("How many seats: ", numberOfSeats);

    const isValid = await isCapacityValid(selectedEvent, numberOfSeats);
    console.log("Are there still some seats left?", isValid);
    // when REGISTER FOR EVENT is clicked, it does not fire the message below even though !isValid
    if (!isValid) {
      console.log("Clicked the button a second time: ", !isValid);
      return Promise.reject({
        Message:
          "Thank you for your interest in this NFIB event. Currently, no seats are available. If you have questions, please contact NFIB by calling the number provided in the event description or 1-800-NFIB-NOW."
      });
    }

第一次单击时，它应该向用户提供您在上面在Promise.reject中看到的警报消息，但这不会发生，直到用户第二次单击REGISTER FOR EVENT并且消息警报出现一秒钟然后<Loading />组件及其动画 gif 无限期地运行并冻结应用程序。 我无法确定哪个<Loading />组件在整个应用程序中运行，因为if条件中有很多组件。 我仍在经历它们，但有人知道会发生什么吗？

Answer 1

因为 Promise 是同步的，你可能正在等待下一个 function。 我觉得通过基本用法解决这个问题还是不错的

return await Promise.reject({
        Message:
          "Thank you for your interest in this NFIB event. Currently, no seats are available. If you have questions, please contact NFIB by calling the number provided in the event description or 1-800-NFIB-NOW."
      }).then(function(reason) {
  // Not called.
}, function(reason) {
  console.log(reason); // [object object]
});

如果您想同时使用解决和拒绝，您可以：

return await new Promise(function (resolve, reject) {
      if (isValid) {
        resolve("resolve");
      } else {
         reject({
           Message:
             "Thank you for your interest in this NFIB event. Currently, no seats are available. If you have questions, please contact NFIB by calling the number provided in the event description or 1-800-NFIB-NOW."
         });
      }
    });