Reactjs 收到警告:Can';t在未安装的组件上执行React状态更新
每次运行此操作时,都会出现两次此错误。我进行了搜索,并试图取消对cleanup函数中的Reactjs 收到警告:Can';t在未安装的组件上执行React状态更新,reactjs,react-native,react-router,react-hooks,expo,Reactjs,React Native,React Router,React Hooks,Expo,每次运行此操作时,都会出现两次此错误。我进行了搜索,并试图取消对cleanup函数中的onAuthStateChanged()到useEffect()的订阅,但仍然收到相同的错误。另外,uploadAndCreate()函数工作得非常好,但是createPlan()甚至在createPlan()完成之前就被调用了,因为fileUrl的未定义 import React, { useState, useEffect } from "react"; import { Ima
onAuthStateChanged()
到useEffect()
的订阅,但仍然收到相同的错误。另外,uploadAndCreate()
函数工作得非常好,但是createPlan()
甚至在createPlan()
完成之前就被调用了,因为fileUrl
的未定义
import React, { useState, useEffect } from "react";
import {
Image,
StyleSheet,
Text,
TextInput,
TouchableOpacity,
View,
} from "react-native";
import firebase from "firebase/app";
import "firebase/auth";
import "firebase/storage";
import { Link, Redirect } from "react-router-native";
import { getDocumentAsync } from "expo-document-picker";
import plus from "../../assets/plus.png";
import cross from "../../assets/cross.png";
const NewPlan = (props) => {
const [planName, setPlanName] = useState();
const [categoryName, setCategoryName] = useState();
const [isPlanCreated, setIsPlanCreated] = useState(false);
const [currUserId, setCurrUserId] = useState();
const [uploadProgress, setUploadProgress] = useState(0);
const [blob, setBlob] = useState({});
const [isPlanNameValid, setIsPlanNameValid] = useState(true);
const [ref, setRef] = useState();
const [fileUrl, setFileUrl] = useState();
useEffect(() => {
let mounted = true;
if (mounted) {
firebase.auth().onAuthStateChanged((user) => {
if (user) {
setCurrUserId(user.uid);
}
});
}
return () => {
mounted = false;
};
}, []);
const validate = () => {
if (planName) {
setIsPlanNameValid(true);
uploadAndCreate();
} else {
setIsPlanNameValid(false);
}
};
const uploadAndCreate = async () => {
if (Object.keys(blob).length !== 0) {
let task = ref.put(blob);
await task.on(
"state_changed",
(snapshot) => {
let progress =
(snapshot.bytesTransferred / snapshot.totalBytes) * 100;
if (firebase.storage.TaskState.RUNNING)
setUploadProgress(progress);
},
(error) => {
console.log("Error uploading file: " + error);
},
() => {
task.snapshot.ref.getDownloadURL().then((downloadURL) => {
setFileUrl(downloadURL);
});
}
);
}
createPlan();
setIsPlanCreated(true);
};
const createPlan = () => {
let plansRef = firebase.database().ref().child("plans");
let newPlanRef = plansRef.push();
newPlanRef.set({
plan_id: newPlanRef.key,
plan_name: planName,
created_by: currUserId,
project_id: props.match.params.id,
status: "active",
category: categoryName || "uncategorized",
file_url: fileUrl || "",
});
};
const handlePlanName = (_planName) => setPlanName(_planName);
return isPlanCreated ? (
<Redirect to={"/project/" + props.match.params.id} />
) : (
<View style={styles.container}>
<Link
to={"/project/" + props.match.params.id}
style={styles.crossContainer}
>
<Image source={cross} style={styles.cross} />
</Link>
<View style={styles.topArea}>
<Image source={plus} style={styles.plus} />
<Text style={styles.title}>New Plan</Text>
{!isPlanNameValid ? (
<Text style={styles.errorText}>
Please enter a valid name.
</Text>
) : null}
<TextInput
placeholder="Plan Name"
style={styles.input}
placeholderTextColor="#fff"
onChangeText={handlePlanName}
/>
{uploadProgress > 0 && uploadProgress < 100 ? (
<Text>Upload Progress: {uploadProgress.toFixed(0)}%</Text>
) : null}
{uploadProgress === 100 ? <Text>Upload Complete</Text> : null}
<TouchableOpacity
style={styles.button}
onPress={() => {
getDocumentAsync().then(async (response) => {
try {
let storageRef = firebase.storage().ref();
setRef(
storageRef.child(
response.uri.split("/")[14]
)
);
let fetchResponse = await fetch(response.uri);
let blob = await fetchResponse.blob();
setBlob(blob);
} catch (error) {
console.log(error.message);
}
});
}}
>
<Text style={styles.buttonText}>Upload Plan</Text>
</TouchableOpacity>
</View>
<TouchableOpacity
style={styles.bottomArea}
onPress={() => {
validate();
}}
>
<Text style={styles.createText}>Create</Text>
</TouchableOpacity>
</View>
);
};
const styles = StyleSheet.create({
// -- STYLES --
});
export default NewPlan;
import React,{useState,useffect}来自“React”;
进口{
形象,,
样式表,
文本,
文本输入,
可触摸不透明度,
看法
}从“反应本族语”;
从“firebase/app”导入firebase;
导入“firebase/auth”;
导入“firebase/storage”;
从“react router native”导入{Link,Redirect};
从“expo文档选择器”导入{GetDocumentSync};
从“../../assets/plus.png”导入plus;
从“../../assets/cross.png”导入交叉点;
const NewPlan=(道具)=>{
const[planName,setPlanName]=useState();
常量[categoryName,setCategoryName]=useState();
const[isPlanCreated,setIsPlanCreated]=useState(false);
const[currUserId,setCurrUserId]=useState();
const[uploadProgress,setUploadProgress]=useState(0);
const[blob,setBlob]=useState({});
常量[isPlanNameValid,setIsPlanNameValid]=useState(true);
const[ref,setRef]=useState();
const[fileUrl,setFileUrl]=useState();
useffect(()=>{
让我们假设这是真的;
如果(已安装){
firebase.auth().onAuthStateChanged((用户)=>{
如果(用户){
setCurrUserId(user.uid);
}
});
}
return()=>{
安装=错误;
};
}, []);
常量验证=()=>{
if(平面名称){
setIsPlanNameValid(true);
uploadAndCreate();
}否则{
setIsPlanNameValid(false);
}
};
const uploadAndCreate=async()=>{
if(Object.keys(blob).length!==0){
让任务=参考放置(blob);
等待任务(
“状态已更改”,
(快照)=>{
让进步=
(snapshot.bytesttransfered/snapshot.totalBytes)*100;
if(firebase.storage.TaskState.RUNNING)
设置加载进度(进度);
},
(错误)=>{
log(“上传文件时出错:+错误”);
},
() => {
task.snapshot.ref.getDownloadURL()。然后((downloadURL)=>{
setFileUrl(下载URL);
});
}
);
}
createPlan();
setIsPlanCreated(真);
};
const createPlan=()=>{
设plansRef=firebase.database().ref().child(“计划”);
设newPlanRef=plansRef.push();
新平面参考集({
计划id:newPlanRef.key,
计划名称:计划名称,
创建人:currUserId,
项目id:props.match.params.id,
状态:“活动”,
类别:categoryName | |“未分类”,
文件url:fileUrl | |“”,
});
};
const handlePlanName=(_planName)=>setPlanName(_planName);
是否创建了返回(
) : (
新计划
{!isplanname有效吗(
请输入有效的名称。
):null}
{uploadProgress>0&&uploadProgress<100(
上载进度:{uploadProgress.toFixed(0)}%
):null}
{uploadProgress==100?上载完成:null}
{
getDocumentAsync()。然后(异步(响应)=>{
试一试{
设storageRef=firebase.storage().ref();
setRef(
storageRef.child(
response.uri.split(“/”[14]
)
);
let fetchResponse=wait fetch(response.uri);
让blob=等待fetchResponse.blob();
setBlob(blob);
}捕获(错误){
console.log(错误消息);
}
});
}}
>
上传计划
{
验证();
}}
>
创造
);
};
const styles=StyleSheet.create({
//--风格--
});
导出默认的新计划;
装入的变量没有任何作用。它唯一被选中的地方是useffect
的开头,在那里它肯定是true
虽然您可以在onAuthStateChanged
回调中检查它:
firebase.auth().onAuthStateChanged((user) => {
if (mounted && user) {
setCurrUserId(user.uid);
}
});
最好使用firebase返回的unsubscribe函数:
useEffect(() => firebase.auth().onAuthStateChanged((user) => {
if (user) {
setCurrUserId(user.uid);
}
}), []);
或者,脱糖:
useEffect(() => {
const unsubscribe = firebase.auth().onAuthStateChanged((user) => {
if (user) {
setCurrUserId(user.uid);
}
});
return unsubscribe;
}, []);
在卸载组件时,您可能会执行多个异步操作,但实际上很难取消这些操作。您可以添加一个ref,指示组件当前是否已装入,并在调用任何setter函数之前检查:
const mountedRef = useRef(true);
useEffect(() => {
const unsubscribe = firebase.auth().onAuthStateChanged((user) => {
if (user) {
setCurrUserId(user.uid);
}
});
return () => {
mountedRef.current = false;
unsubscribe();
}
}, []);
然后,例如,代替
setBlob(blob);
做
如果有可能异步运行的setter,请遵循相同的模式。您的装入的变量没有任何作用。唯一的地方是ch
if (mountedRef.current) {
setBlob(blob);
};