英文:
React Context is not updating Data
问题
以下是您要翻译的内容:
I have created a React Context API, I have stored information such as first_name, hobbies, DOB etc in it. I have created a state in the context file and a function that changes the state when called. I am using the context in SignUpForm1.js and SignUpForm2.js, I am trying to update the state of context variables whenever there is a change in the text field, but the data in the context is not updating.
UserData.js (Context)
```javascript
import React from "react";
import { useState } from "react";
import {Text} from 'react-native';
import { createContext } from "react";
const SignUpContext = React.createContext({});
const UserData = (props)=>{
var state = {
pref_pronoun: "",
DOB: "",
course: "",
first_name: "",
hobby_1: "",
hobby_2: "",
hobby_3: "",
hobby_4: "",
hobby_5: "",
home_city: "",
last_name: "",
nationality: "",
student_email: "",
university: "",
}
const [userDetails , setDetails] = useState(state);
const updateFormData = (field, value) => {
setDetails({ [field]: value });
console.log(state);
};
return (
<SignUpContext.Provider value = {{state, updateFormData}}>
{props.children}
</SignUpContext.Provider>
)
}
export {SignUpContext, UserData} ;
SignUpForm1.js
import {
Image,
Text,
StyleSheet,
View,
StatusBar,
ScrollView,
RefreshControl,
} from "react-native";
import DropDown from "./DropDown";
import Input from "./Input";
import {
KeyboardAvoidingView,
TouchableWithoutFeedback,
Keyboard,
} from "react-native";
import { useCallback, useContext, useState } from "react";
import CustomButton from "./CustomButton";
import { useNavigation } from "@react-navigation/native";
import DateTimePickerModal from "react-native-modal-datetime-picker";
import { Button } from "react-native";
import { SignUpContext, UserData } from "./GlobalUtil/UserData";
const HideKeyboard = ({ children }) => (
<TouchableWithoutFeedback onPress={() => Keyboard.dismiss()}>
{children}
</TouchableWithoutFeedback>
);
function SignUpForm1() {
const [isDatePickerVisible, setDatePickerVisibility] = useState(false);
const s_context = useContext(SignUpContext);
const showDatePicker = () => {
setDatePickerVisibility(true);
};
const hideDatePicker = () => {
setDatePickerVisibility(false);
};
const navigation = useNavigation();
const NationalityData = ["Football", "Cricket", "Programming", "Coding"];
const [refreshing, setRefreshing] = useState(false);
const onRefresh = useCallback(() => {
setRefreshing(true);
setTimeout(() => {
setRefreshing(false);
}, 2000);
}, []);
const statusBarHeight = Platform.OS === "ios" ? 50 : StatusBar.currentHeight;
return (
<KeyboardAvoidingView behavior="padding">
<HideKeyboard>
<View
style={{
height: "100%",
width: "100%",
backgroundColor: "#f1be63",
}}
>
<View
style={{ backgroundColor: "#f1be63", height: statusBarHeight }}
>
<StatusBar barStyle="dark-content" />
</View>
<ScrollView
contentContainerStyle={styles.rootContainer}
refreshControl={
<RefreshControl
refreshing={refreshing}
onRefresh={onRefresh}
/>
}
>
<Image
source={require("../assets/aeroplane.png")}
style={styles.image}
resizeMode="contain"
/>
<Text style={styles.header}>Let's get you set up</Text>
<Text style={styles.lowerHeader}>
(we promise that it won't take long)
</Text>
<View style={[styles.textFieldsContainer]}>
<View style={{ alignItems: "center" }}>
<Input
isLabel={true}
label="Preferred Pronoun"
placeholder="He/Him"
onChangeText={(text) => {
s_context.updateFormData("pref_pronoun", text);
}}
/>
<Input
isLabel={true}
label="First Name"
placeholder="Cameron"
onChangeText={(text) => {
s_context.updateFormData("first_name", text);
}}
/>
<Input
isLabel={true}
label="Last Name"
placeholder="Cox"
onChangeText={(text) => {
s_context.updateFormData("last_name", text);
}}
/>
<View
style={{
backgroundColor: "white",
width: "80%",
borderRadius: 5,
marginTop: 10,
}}
>
<Button
title="Date of Birth"
onPress={showDatePicker}
color="gray"
/>
</View>
<DateTimePickerModal
isVisible={isDatePickerVisible}
mode="date"
onConfirm={(date) => {
s_context.updateFormData('dob', date);
hideDatePicker();
}}
onCancel={hideDatePicker}
buttonTextColorIOS="white"
pickerContainerStyleIOS={{ backgroundColor: "#D89D35" }}
isDarkModeEnabled
/>
</View>
<View style={{ alignItems: "center" }}>
<DropDown
data={NationalityData}
placeholder="Nationality"
onSelect={(selectedItem, index) => {
s_context.updateFormData("nationality", selectedItem);
}}
/>
<DropDown
data={NationalityData}
placeholder="University"
onSelect={(selectedItem, index) => {
s_context.updateFormData("university", selectedItem);
}}
/>
<DropDown
data={NationalityData}
placeholder="Course"
onSelect={(selectedItem, index) => {
s_context.updateFormData("course", selectedItem);
}}
/>
<DropDown
data={NationalityData}
placeholder="HomeTown City"
onSelect={(selectedItem, index) => {
s_context.updateFormData("homeCity", selectedItem);
}}
/>
<CustomButton
isBorder={true}
title="Next"
onPress={() => {
navigation.navigate("SignUp2");
}}
/>
</View>
</View>
</ScrollView>
</View>
</HideKeyboard>
</KeyboardAvoidingView>
);
}
const styles = StyleSheet.create({
rootContainer: {
height: "125%",
justifyContent: "flex-start",
alignItems: "center",
marginTop: 24,
},
textFieldsContainer: {
width: "100%",
flex: 1,
},
image: {
width: "25%",
height: "10%",
marginTop: 24,
},
header: {
color: "white",
fontSize: 26,
fontWeight: "bold",
marginVertical: 6,
},
lowerHeader: {
color: "white",
fontSize: 12,
marginBottom: 24,
},
});
export default SignUpForm1;
英文:
I have created a React Context API, I have stored information such as first_name, hobbies, DOB etc in it. I have crated a state in the context file and a function that changes the state when called. I am using the context in SignUpForm1.js and SignUpForm2.js, I am trying to update the state of context variables when ever there is a change in the text field, but the data in the context is not updating.
UserData.js (Context)
import React from "react";
import { useState } from "react";
import {Text} from 'react-native';
import { createContext } from "react";
const SignUpContext = React.createContext({});
const UserData = (props)=>{
var state = {
pref_pronoun: "",
DOB: "",
course: "",
first_name: "",
hobby_1: "",
hobby_2: "",
hobby_3: "",
hobby_4: "",
hobby_5: "",
home_city: "",
last_name: "",
nationality: "",
student_email: "",
university: "",
}
const [userDetails , setDetails] = useState(state);
const updateFormData = (field, value) => {
setDetails({ [field]: value });
console.log(state);
};
return (
<SignUpContext.Provider value = {{state, updateFormData}}>
{props.children}
</SignUpContext.Provider>
)
}
export {SignUpContext, UserData} ;
SignUpForm1.js
import {
Image,
Text,
StyleSheet,
View,
StatusBar,
ScrollView,
RefreshControl,
} from "react-native";
import DropDown from "./DropDown";
import Input from "./Input";
import {
KeyboardAvoidingView,
TouchableWithoutFeedback,
Keyboard,
} from "react-native";
import { useCallback, useContext, useState } from "react";
import CustomButton from "./CustomButton";
import { useNavigation } from "@react-navigation/native";
import DateTimePickerModal from "react-native-modal-datetime-picker";
import { Button } from "react-native";
import { SignUpContext, UserData } from "./GlobalUtil/UserData";
const HideKeyboard = ({ children }) => (
<TouchableWithoutFeedback onPress={() => Keyboard.dismiss()}>
{children}
</TouchableWithoutFeedback>
);
function SignUpForm1() {
const [isDatePickerVisible, setDatePickerVisibility] = useState(false);
const s_context = useContext(SignUpContext);
const showDatePicker = () => {
setDatePickerVisibility(true);
};
const hideDatePicker = () => {
setDatePickerVisibility(false);
};
const navigation = useNavigation();
const NationalityData = ["Football", "Cricket", "Programmming", "Coding"];
const [refreshing, setRefreshing] = useState(false);
const onRefresh = useCallback(() => {
setRefreshing(true);
setTimeout(() => {
setRefreshing(false);
}, 2000);
}, []);
const statusBarHeight = Platform.OS === "ios" ? 50 : StatusBar.currentHeight;
return (
<KeyboardAvoidingView behavior="padding">
<HideKeyboard>
<View
style={{
height: "100%",
width: "100%",
backgroundColor: "#f1be63",
}}
>
<View
style={{ backgroundColor: "#f1be63", height: statusBarHeight }}
>
<StatusBar barStyle="dark-content" />
</View>
<ScrollView
contentContainerStyle={styles.rootContainer}
refreshControl={
<RefreshControl
refreshing={refreshing}
onRefresh={onRefresh}
/>
}
>
<Image
source={require("../assets/aeroplane.png")}
style={styles.image}
resizeMode="contain"
/>
<Text style={styles.header}>Let's get you set up</Text>
<Text style={styles.lowerHeader}>
(we promise that it won't take long)
</Text>
<View style={[styles.textFieldsContainer]}>
<View style={{ alignItems: "center" }}>
<Input
isLabel={true}
label="Preferred Pronoun"
placeholder="He/Him"
onChangeText={(text) => {
s_context.updateFormData("pref_pronoun", text);
}}
/>
<Input
isLabel={true}
label="First Name"
placeholder="Cameron"
onChangeText={(text) => {
s_context.updateFormData("first_name", text);
}}
/>
<Input
isLabel={true}
label="Last Name"
placeholder="Cox"
onChangeText={(text) => {
s_context.updateFormData("last_name", text);
}}
/>
<View
style={{
backgroundColor: "white",
width: "80%",
borderRadius: 5,
marginTop: 10,
}}
>
<Button
title="Date of Birth"
onPress={showDatePicker}
color="gray"
/>
</View>
<DateTimePickerModal
isVisible={isDatePickerVisible}
mode="date"
onConfirm={(date) => {
s_context.updateFormData('dob', date);
hideDatePicker();
}}
onCancel={hideDatePicker}
buttonTextColorIOS="white"
pickerContainerStyleIOS={{ backgroundColor: "#D89D35" }}
isDarkModeEnabled
/>
</View>
<View style={{ alignItems: "center" }}>
<DropDown
data={NationalityData}
placeholder="Nationality"
onSelect={(selectedItem, index) => {
s_context.updateFormData("nationality", selectedItem);
}}
/>
<DropDown
data={NationalityData}
placeholder="University"
onSelect={(selectedItem, index) => {
s_context.updateFormData("university", selectedItem);
}}
/>
<DropDown
data={NationalityData}
placeholder="Course"
onSelect={(selectedItem, index) => {
s_context.updateFormData("course", selectedItem);
}}
/>
<DropDown
data={NationalityData}
placeholder="HomeTown City"
onSelect={(selectedItem, index) => {
s_context.updateFormData("homeCity", selectedItem);
}}
/>
<CustomButton
isBorder={true}
title="Next"
onPress={() => {
navigation.navigate("SignUp2");
}}
/>
</View>
</View>
</ScrollView>
</View>
</HideKeyboard>
</KeyboardAvoidingView>
);
}
const styles = StyleSheet.create({
rootContainer: {
height: "125%",
justifyContent: "flex-start",
alignItems: "center",
marginTop: 24,
},
textFieldsContainer: {
width: "100%",
flex: 1,
},
image: {
width: "25%",
height: "10%",
marginTop: 24,
},
header: {
color: "white",
fontSize: 26,
fontWeight: "bold",
marginVertical: 6,
},
lowerHeader: {
color: "white",
fontSize: 12,
marginBottom: 24,
},
});
export default SignUpForm1;
SignUpForm2.js
import {
View,
Text,
TouchableWithoutFeedback,
StyleSheet,
StatusBar,
ScrollView,
} from "react-native";
import { KeyboardAvoidingView } from "react-native";
import { Avatar } from "react-native-elements";
import Input from "./Input";
import DropDown from "./DropDown";
import { Keyboard } from "react-native";
import { Platform } from "react-native";
import { useNavigation } from "@react-navigation/native";
import CustomButton from "./CustomButton";
import { useState, useContext } from "react";
import { createNewUser } from "./util/auth";
import { SignUpContext, UserData } from "./GlobalUtil/UserData";
const HideKeyboard = ({ children }) => (
<TouchableWithoutFeedback onPress={() => Keyboard.dismiss()}>
{children}
</TouchableWithoutFeedback>
);
function SignUpForm2() {
const s_context = useContext(SignUpContext);
async function FinishBtnHandler()
{
console.log("Creating New User");
console.log("Email: " + emailText.trim());
console.log("Password: " + passwordText.trim());
await createNewUser(emailText.trim(), passwordText.trim());
}
const navigation = useNavigation();
const hobbiesData = ["Football", "Cricket", "Programmming", "Coding"];
const [emailText, setEmailText] = useState("");
function handleEmailText(newText) {
console.log("Email: " + newText);
setEmailText(newText);
}
const [passwordText, setPasswordText] = useState("");
function handlePasswordText(newText) {
console.log("Password: " + newText);
setPasswordText(newText);
}
function avatarPressHandler() {
console.log("Pressed!");
}
const statusBarHeight = Platform.OS === "ios" ? 50 : StatusBar.currentHeight;
return (
<KeyboardAvoidingView behavior="padding" style={{ flex: 1 }}>
<HideKeyboard>
<ScrollView>
<View
style={{
position: "absolute",
top: 0,
left: 0,
right: 0,
zIndex: 999,
}}
>
<View
style={{
backgroundColor: "#f1be63",
height: statusBarHeight,
}}
>
<StatusBar barStyle="dark-content" />
</View>
</View>
<View style={[styles.rootContainer, { paddingBottom: 48 }]}>
<View style={styles.lowerContainer}>
<Text style={styles.primaryText}>You're almost there!</Text>
<Avatar
rounded
size={170}
containerStyle={{ alignSelf: "center", marginTop: 24 }}
//icon={{ name: "user", type: "font-awesome" }}
overlayContainerStyle={{ backgroundColor: "#f1be63" }}
source={{
uri: "https://cdn.pixabay.com/photo/2019/11/03/20/11/portrait-4599553__340.jpg",
}}
>
<Avatar.Accessory size={20} onPress={avatarPressHandler} />
</Avatar>
<Text
style={[
styles.secondaryText,
{ marginBottom: 8, marginTop: 16 },
]}
>
Express yourself & customize your avatar
</Text>
<Input
isLabel={true}
label="Student Email"
placeholder="cce22rnu@uea.ac.uk"
onChangeText={handleEmailText}
defaultValue={emailText}
/>
<Input
isLabel={true}
label="Create Password"
placeholder="iLoveyoushakila123"
onChangeText={handlePasswordText}
defaultValue={passwordText}
/>
<Input
isLabel={true}
label="Confirm Password"
placeholder="iLoveyoushakila123"
/>
<Text style={styles.secondaryText}>
Now the exciting part - select your top 5 hobbies
</Text>
<View style={{ alignItems: "center", marginTop: 16 }}>
<DropDown
data={hobbiesData}
onSelect={(selectedItem, index) => {
s_context.updateFormData("hobby_1", selectedItem);
}}
/>
<DropDown data={hobbiesData} onSelect={(selectedItem, index) => {
s_context.updateFormData("hobby_2", selectedItem);
}}/>
<DropDown data={hobbiesData} onSelect={(selectedItem, index) => {
s_context.updateFormData("hobby_3", selectedItem);
}}/>
<DropDown data={hobbiesData} onSelect={(selectedItem, index) => {
s_context.updateFormData("hobby_4", selectedItem);
}}/>
<DropDown data={hobbiesData} onSelect={(selectedItem, index) => {
s_context.updateFormData("hobby_5", selectedItem);
}}/>
<CustomButton
isBorder={true}
title="Finish"
/*onPress={()=>{navigation.navigate("ConfirmId")}}*/ onPress={
FinishBtnHandler
}
/>
</View>
</View>
</View>
</ScrollView>
</HideKeyboard>
</KeyboardAvoidingView>
);
}
const styles = StyleSheet.create({
rootContainer: {
flex: 1,
justifyContent: "flex-start",
alignItems: "center",
backgroundColor: "#f1be63",
marginTop: 48,
backgroundColor: "#f1be63",
},
lowerContainer: {
flex: 1,
width: "100%",
alignItems: "center",
},
primaryText: {
color: "white",
fontSize: 24,
fontWeight: "bold",
},
secondaryText: {
marginTop: 8,
color: "white",
fontSize: 12,
fontWeight: "bold",
},
});
export default SignUpForm2;
答案1
得分: 3
只返回翻译好的部分:
-
You need to pass your
userDetails
state variable to the context, not the initialstate
value.
你需要将userDetails
状态变量传递给上下文,而不是初始的state
值。 -
Passing the initial state object will not see any updates you make.
传递初始状态对象将不会看到你所做的任何更新。 -
Also, you should use the functional updates format to dynamically set properties in your state.
另外,你应该使用函数更新格式来动态设置状态中的属性。 -
setDetails((prev) => ({ ...prev, [field]: value }));
-
Finally, console logging state is a pointless exercise that often gives unexpected results. Just don't do it.
最后,记录状态到控制台是一个毫无意义的操作,通常会导致意外的结果。不要这样做。
英文:
You need to pass your userDetails
state variable to the context, not the initial state
value
<SignUpContext.Provider value={{ state: userDetails, updateFormData }}>
{props.children}
</SignUpContext.Provider>
Passing the initial state object will not see any updates you make.
Also, you should use the functional updates format to dynamically set properties in your state
setDetails((prev) => ({ ...prev, [field]: value }));
Finally, console logging state is a pointless exercise that often gives unexpected results. Just don't do it
通过集体智慧和协作来改善编程学习和解决问题的方式。致力于成为全球开发者共同参与的知识库,让每个人都能够通过互相帮助和分享经验来进步。
评论