Autentikasi Pengguna dengan Parse di React Native

masuk dan keluar pengguna untuk react native pendahuluan setelah menerapkan komponen yang menangani pendaftaran pengguna di parse pada panduan terakhir, anda sekarang akan belajar bagaimana cara masuk dan keluar pengguna menggunakan parse user parse user kelas yang sama anda juga akan belajar cara menginstal dan mengonfigurasi react navigation react navigation sehingga anda dapat menavigasi pengguna melalui layar dan komponen baru anda metode parse user login parse user login menyimpan sesi pengguna yang valid di penyimpanan lokal anda, sehingga panggilan berikutnya ke metode seperti currentasync currentasync akan berhasil mengambil data pengguna anda di sisi lain, logout logout akan menghapus sesi ini dari disk dan keluar dari layanan yang terhubung di server parse anda kapan saja, anda dapat mengakses proyek android lengkap yang dibangun dengan tutorial ini di repositori github kami repositori contoh kotlin repositori contoh java prasyarat untuk menyelesaikan tutorial ini, anda akan membutuhkan aplikasi react native yang dibuat dan terhubung ke back4app selesaikan panduan sebelumnya agar anda dapat memiliki pemahaman yang lebih baik tentang kelas pengguna parse tujuan untuk membangun fitur login dan logout pengguna menggunakan parse untuk aplikasi react native 1 menginstal dependensi pada suatu titik, setiap aplikasi di react native akan membutuhkan navigasi layar anda sekarang akan belajar bagaimana cara menginstal dan mengonfigurasi pustaka yang paling banyak digunakan di react native untuk ini, react navigation react navigation pergi ke direktori root proyek anda dan instal dependensi berikut cd yourapp yarn add @react navigation/native react native reanimated react native gesture handler react native screens react native safe area context @react native community/masked view jika anda mengembangkan untuk ios, anda perlu menginstal pod untuk menyelesaikan auto linking aplikasi anda cd ios npx pod install catatan linking bersifat otomatis untuk react native 0 60+ 0 60+ untuk semua platform, jadi jika anda masih menggunakan versi rn yang lebih lama, lihat dokumentasi react native di sini https //reactnative dev/docs/linking libraries ios dalam file entri aplikasi anda ( app tsx app tsx atau app js app js ), tambahkan baris impor ini di bagian paling atas file sekarang anda perlu memindahkan komponen anda ke dalam react navigation react navigation kontainer, yang akan mengenkapsulasi aplikasi anda di dalam navigationcontainer navigationcontainer app tsx/app js 1 import "react native gesture handler"; 2 // your other imports go here 3 import { navigationcontainer } from "@react navigation/native"; 4&#x9; 5 const app = () => { 6 return \<navigationcontainer>{/ your app code /}\</navigationcontainer>; 7 } 8&#x9; 9 export default app; perpustakaan navigasi inti memiliki berbagai modul navigasi tambahan seperti tumpukan, tab, laci, dan lainnya navigator tumpukan adalah yang paling sederhana dan yang akan anda gunakan dalam panduan ini lanjutkan dengan instalasi \# ini adalah navigator yang akan anda gunakan yarn add @react navigation/stack 2 membuat stacknavigator sekarang mari kita buat dan atur stacknavigator stacknavigator modul ini akan mengelola dan menangani navigasi layar di aplikasi anda karena bukan tujuan di sini untuk memberikan pemahaman yang mendalam tentang react navigation react navigation , silakan kunjungi dokumentasi resmi https //reactnavigation org/docs/hello react navigation/ untuk mengetahui lebih lanjut di app js app js ( app tsx app tsx jika anda menggunakan typescript) file, impor dan buat sebuah stacknavigator stacknavigator , buat sebuah fungsi yang berisi layar pendaftaran pengguna anda dan masukkan navigator di dalam aplikasi anda navigationcontainer navigationcontainer file utama anda harus terlihat seperti ini app tsx/app js 1 import 'react native gesture handler'; 2 import react from 'react'; 3 import {image, safeareaview, statusbar, text, view} from 'react native'; 4&#x9; 5 import asyncstorage from '@react native async storage/async storage'; 6 import parse from 'parse/react native'; 7 import {navigationcontainer} from '@react navigation/native'; 8 import {createstacknavigator} from '@react navigation/stack'; 9 import {userregistration} from ' /userregistration'; 10 import styles from ' /styles'; 11&#x9; 12 // your parse initialization configuration goes here 13 parse setasyncstorage(asyncstorage); 14 const parse application id string = 'application id'; 15 const parse host url string = 'host url'; 16 const parse javascript id string = 'javascript id'; 17 parse initialize(parse application id, parse javascript id); 18 parse serverurl = parse host url; 19&#x9; 20 // wrap your old app screen in a separate function, so you can create a screen 21 // inside the navigator; you can also declare your screens in a separate file, 22 // export and import here to reduce some clutter 23 function userregistrationscreen() { 24 return ( 25 <> 26 \<statusbar /> 27 \<safeareaview style={styles login container}> 28 \<view style={styles login header}> 29 \<image 30 style={styles login header logo} 31 source={require(' /assets/logo back4app png')} 32 /> 33 \<text style={styles login header text}> 34 \<text style={styles login header text bold}> 35 {'react native on back4app '} 36 \</text> 37 {' user registration'} 38 \</text> 39 \</view> 40 \<userregistration /> 41 \</safeareaview> 42 \</> 43 ); 44 } 45&#x9; 46 // create your main navigator here 47 const stack = createstacknavigator(); 48&#x9; 49 // add the stack navigator to your navigationcontainer 50 // and in it you can add all your app screens in the order you need 51 // them on your stack 52 const app = () => { 53 return ( 54 \<navigationcontainer> 55 \<stack navigator> 56 \<stack screen name="sign up" component={userregistrationscreen} /> 57 \</stack navigator> 58 \</navigationcontainer> 59 ); 60 }; 61&#x9; 62 export default app; jika anda menjalankan aplikasi anda sekarang, anda akan melihat adanya header di bagian atas layar yang berisi nama layar anda 3 membuat komponen login sekarang mari kita bangun userlogin userlogin komponen fungsional di aplikasi anda buat file baru di direktori root anda yang disebut userlogin js userlogin js ( userlogin tsx userlogin tsx jika anda menggunakan typescript) dan tambahkan elemen input menggunakan state hooks untuk mengelola datanya userlogin js 1 import react, {fc, reactelement, usestate} from 'react'; 2 import { 3 image, 4 text, 5 textinput, 6 touchableopacity, 7 view, 8 } from 'react native'; 9 import parse from 'parse/react native'; 10 import styles from ' /styles'; 11&#x9; 12 export const userlogin = () => { 13 const \[username, setusername] = usestate(""); 14 const \[password, setpassword] = usestate(""); 15&#x9; 16 return ( 17 \<view style={styles login wrapper}> 18 \<view style={styles form}> 19 \<textinput 20 style={styles form input} 21 value={username} 22 placeholder={'username'} 23 onchangetext={(text) => setusername(text)} 24 autocapitalize={'none'} 25 keyboardtype={'email address'} 26 /> 27 \<textinput 28 style={styles form input} 29 value={password} 30 placeholder={'password'} 31 securetextentry 32 onchangetext={(text) => setpassword(text)} 33 /> 34 \<touchableopacity onpress={() => {}}> 35 \<view style={styles button}> 36 \<text style={styles button label}>{'sign in'}\</text> 37 \</view> 38 \</touchableopacity> 39 \</view> 40 \<view style={styles login social}> 41 \<view style={styles login social separator}> 42 \<view style={styles login social separator line} /> 43 \<text style={styles login social separator text}>{'or'}\</text> 44 \<view style={styles login social separator line} /> 45 \</view> 46 \<view style={styles login social buttons}> 47 \<touchableopacity> 48 \<view 49 style={\[ 50 styles login social button, 51 styles login social facebook, 52 ]}> 53 \<image 54 style={styles login social icon} 55 source={require(' /assets/icon facebook png')} 56 /> 57 \</view> 58 \</touchableopacity> 59 \<touchableopacity> 60 \<view style={styles login social button}> 61 \<image 62 style={styles login social icon} 63 source={require(' /assets/icon google png')} 64 /> 65 \</view> 66 \</touchableopacity> 67 \<touchableopacity> 68 \<view style={styles login social button}> 69 \<image 70 style={styles login social icon} 71 source={require(' /assets/icon apple png')} 72 /> 73 \</view> 74 \</touchableopacity> 75 \</view> 76 \</view> 77 \</view> 78 ); 79 }; userlogin tsx 1 import react, {fc, reactelement, usestate} from 'react'; 2 import { 3 image, 4 text, 5 textinput, 6 touchableopacity, 7 view, 8 } from 'react native'; 9 import parse from 'parse/react native'; 10 import styles from ' /styles'; 11&#x9; 12 export const userlogin fc<{}> = ({}) reactelement => { 13 const \[username, setusername] = usestate(""); 14 const \[password, setpassword] = usestate(""); 15&#x9; 16 return ( 17 \<view style={styles login wrapper}> 18 \<view style={styles form}> 19 \<textinput 20 style={styles form input} 21 value={username} 22 placeholder={'username'} 23 onchangetext={(text) => setusername(text)} 24 autocapitalize={'none'} 25 keyboardtype={'email address'} 26 /> 27 \<textinput 28 style={styles form input} 29 value={password} 30 placeholder={'password'} 31 securetextentry 32 onchangetext={(text) => setpassword(text)} 33 /> 34 \<touchableopacity onpress={() => {}}> 35 \<view style={styles button}> 36 \<text style={styles button label}>{'sign in'}\</text> 37 \</view> 38 \</touchableopacity> 39 \</view> 40 \<view style={styles login social}> 41 \<view style={styles login social separator}> 42 \<view style={styles login social separator line} /> 43 \<text style={styles login social separator text}>{'or'}\</text> 44 \<view style={styles login social separator line} /> 45 \</view> 46 \<view style={styles login social buttons}> 47 \<touchableopacity> 48 \<view 49 style={\[ 50 styles login social button, 51 styles login social facebook, 52 ]}> 53 \<image 54 style={styles login social icon} 55 source={require(' /assets/icon facebook png')} 56 /> 57 \</view> 58 \</touchableopacity> 59 \<touchableopacity> 60 \<view style={styles login social button}> 61 \<image 62 style={styles login social icon} 63 source={require(' /assets/icon google png')} 64 /> 65 \</view> 66 \</touchableopacity> 67 \<touchableopacity> 68 \<view style={styles login social button}> 69 \<image 70 style={styles login social icon} 71 source={require(' /assets/icon apple png')} 72 /> 73 \</view> 74 \</touchableopacity> 75 \</view> 76 \</view> 77 \</view> 78 ); 79 }; anda sekarang dapat mengimplementasikan fungsi yang akan memanggil parse user login parse user login metode, menggunakan variabel status javascript 1 const douserlogin = async function () { 2 // note that these values come from state variables that we've declared before 3 const usernamevalue = username; 4 const passwordvalue = password; 5 return await parse user login(usernamevalue, passwordvalue) 6 then(async (loggedinuser) => { 7 // login returns the corresponding parseuser object 8 alert alert( 9 'success!', 10 `user ${loggedinuser get('username')} has successfully signed in!`, 11 ); 12 // to verify that this is in fact the current user, currentasync can be used 13 const currentuser = await parse user currentasync(); 14 console log(loggedinuser === currentuser); 15 return true; 16 }) 17 catch((error) => { 18 // error can be caused by wrong parameters or lack of internet connection 19 alert alert('error!', error message); 20 return false; 21 }); 22 };1 const douserlogin = async function () promise\<boolean> { 2 // note that these values come from state variables that we've declared before 3 const usernamevalue string = username; 4 const passwordvalue string = password; 5 return await parse user login(usernamevalue, passwordvalue) 6 then(async (loggedinuser parse user) => { 7 // login returns the corresponding parseuser object 8 alert alert( 9 'success!', 10 `user ${loggedinuser get('username')} has successfully signed in!`, 11 ); 12 // to verify that this is in fact the current user, currentasync can be used 13 const currentuser parse user = await parse user currentasync(); 14 console log(loggedinuser === currentuser); 15 return true; 16 }) 17 catch((error object) => { 18 // error can be caused by wrong parameters or lack of internet connection 19 alert alert('error!', error message); 20 return false; 21 }); 22 }; masukkan fungsi ini ke dalam userlogin userlogin komponen, tepat sebelum return return dipanggil, untuk dipanggil dan diuji ingat untuk memperbarui tombol login formulir onpress onpress aksi menjadi () => douserlogin() () => douserlogin() dan untuk mengimpor alert alert dari react native react native komponen anda sekarang harus terlihat seperti ini userlogin js 1 import react, {fc, reactelement, usestate} from 'react'; 2 import { 3 alert, 4 image, 5 text, 6 textinput, 7 touchableopacity, 8 view, 9 } from 'react native'; 10 import parse from 'parse/react native'; 11 import styles from ' /styles'; 12&#x9; 13 export const userlogin = () => { 14 const \[username, setusername] = usestate(''); 15 const \[password, setpassword] = usestate(''); 16&#x9; 17 const douserlogin = async function () { 18 // note that these values come from state variables that we've declared before 19 const usernamevalue = username; 20 const passwordvalue = password; 21 return await parse user login(usernamevalue, passwordvalue) 22 then(async (loggedinuser) => { 23 // login returns the corresponding parseuser object 24 alert alert( 25 'success!', 26 `user ${loggedinuser get('username')} has successfully signed in!`, 27 ); 28 // to verify that this is in fact the current user, currentasync can be used 29 const currentuser = await parse user currentasync(); 30 console log(loggedinuser === currentuser); 31 return true; 32 }) 33 catch((error) => { 34 // error can be caused by wrong parameters or lack of internet connection 35 alert alert('error!', error message); 36 return false; 37 }); 38 }; 39&#x9; 40 return ( 41 \<view style={styles login wrapper}> 42 \<view style={styles form}> 43 \<textinput 44 style={styles form input} 45 value={username} 46 placeholder={'username'} 47 onchangetext={(text) => setusername(text)} 48 autocapitalize={'none'} 49 keyboardtype={'email address'} 50 /> 51 \<textinput 52 style={styles form input} 53 value={password} 54 placeholder={'password'} 55 securetextentry 56 onchangetext={(text) => setpassword(text)} 57 /> 58 \<touchableopacity onpress={() => douserlogin()}> 59 \<view style={styles button}> 60 \<text style={styles button label}>{'sign in'}\</text> 61 \</view> 62 \</touchableopacity> 63 \</view> 64 \<view style={styles login social}> 65 \<view style={styles login social separator}> 66 \<view style={styles login social separator line} /> 67 \<text style={styles login social separator text}>{'or'}\</text> 68 \<view style={styles login social separator line} /> 69 \</view> 70 \<view style={styles login social buttons}> 71 \<touchableopacity> 72 \<view 73 style={\[ 74 styles login social button, 75 styles login social facebook, 76 ]}> 77 \<image 78 style={styles login social icon} 79 source={require(' /assets/icon facebook png')} 80 /> 81 \</view> 82 \</touchableopacity> 83 \<touchableopacity> 84 \<view style={styles login social button}> 85 \<image 86 style={styles login social icon} 87 source={require(' /assets/icon google png')} 88 /> 89 \</view> 90 \</touchableopacity> 91 \<touchableopacity> 92 \<view style={styles login social button}> 93 \<image 94 style={styles login social icon} 95 source={require(' /assets/icon apple png')} 96 /> 97 \</view> 98 \</touchableopacity> 99 \</view> 100 \</view> 101 \</view> 102 ); 103 }; userlogin tsx 1 import react, {fc, reactelement, usestate} from 'react'; 2 import { 3 alert, 4 image, 5 text, 6 textinput, 7 touchableopacity, 8 view, 9 } from 'react native'; 10 import parse from 'parse/react native'; 11 import styles from ' /styles'; 12&#x9; 13 export const userlogin fc<{}> = ({}) reactelement => { 14 const \[username, setusername] = usestate(''); 15 const \[password, setpassword] = usestate(''); 16&#x9; 17 const douserlogin = async function () promise\<boolean> { 18 // note that these values come from state variables that we've declared before 19 const usernamevalue string = username; 20 const passwordvalue string = password; 21 return await parse user login(usernamevalue, passwordvalue) 22 then(async (loggedinuser parse user) => { 23 // login returns the corresponding parseuser object 24 alert alert( 25 'success!', 26 `user ${loggedinuser get('username')} has successfully signed in!`, 27 ); 28 // to verify that this is in fact the current user, currentasync can be used 29 const currentuser parse user = await parse user currentasync(); 30 console log(loggedinuser === currentuser); 31 return true; 32 }) 33 catch((error object) => { 34 // error can be caused by wrong parameters or lack of internet connection 35 alert alert('error!', error message); 36 return false; 37 }); 38 }; 39&#x9; 40 return ( 41 \<view style={styles login wrapper}> 42 \<view style={styles form}> 43 \<textinput 44 style={styles form input} 45 value={username} 46 placeholder={'username'} 47 onchangetext={(text) => setusername(text)} 48 autocapitalize={'none'} 49 keyboardtype={'email address'} 50 /> 51 \<textinput 52 style={styles form input} 53 value={password} 54 placeholder={'password'} 55 securetextentry 56 onchangetext={(text) => setpassword(text)} 57 /> 58 \<touchableopacity onpress={() => douserlogin()}> 59 \<view style={styles button}> 60 \<text style={styles button label}>{'sign in'}\</text> 61 \</view> 62 \</touchableopacity> 63 \</view> 64 \<view style={styles login social}> 65 \<view style={styles login social separator}> 66 \<view style={styles login social separator line} /> 67 \<text style={styles login social separator text}>{'or'}\</text> 68 \<view style={styles login social separator line} /> 69 \</view> 70 \<view style={styles login social buttons}> 71 \<touchableopacity> 72 \<view 73 style={\[ 74 styles login social button, 75 styles login social facebook, 76 ]}> 77 \<image 78 style={styles login social icon} 79 source={require(' /assets/icon facebook png')} 80 /> 81 \</view> 82 \</touchableopacity> 83 \<touchableopacity> 84 \<view style={styles login social button}> 85 \<image 86 style={styles login social icon} 87 source={require(' /assets/icon google png')} 88 /> 89 \</view> 90 \</touchableopacity> 91 \<touchableopacity> 92 \<view style={styles login social button}> 93 \<image 94 style={styles login social icon} 95 source={require(' /assets/icon apple png')} 96 /> 97 \</view> 98 \</touchableopacity> 99 \</view> 100 \</view> 101 \</view> 102 ); 103 }; 4 membuat layar login mari kita buat layar baru untuk aplikasi anda yang akan menggunakan userlogin userlogin komponen tambahkan layar baru sebagai layar pertama (atau atas) dari stacknavigator stacknavigator anda juga app tsx/app js 1 // 2&#x9; 3 // add this new screen function below the userregistrationscreen 4 function userloginscreen() { 5 return ( 6 <> 7 \<statusbar /> 8 \<safeareaview style={styles login container}> 9 \<view style={styles login header}> 10 \<image 11 style={styles login header logo} 12 source={require(' /assets/logo back4app png')} 13 /> 14 \<text style={styles login header text}> 15 \<text style={styles login header text bold}> 16 {'react native on back4app '} 17 \</text> 18 {' user login'} 19 \</text> 20 \</view> 21 \<userlogin /> 22 \</safeareaview> 23 \</> 24 ); 25 } 26&#x9; 27 // 28&#x9; 29 // add the screen as the top one at your stacknavigator 30 const app = () => { 31 return ( 32 \<navigationcontainer> 33 \<stack navigator> 34 \<stack screen name="login" component={userloginscreen} /> 35 \<stack screen name="sign up" component={userregistrationscreen} /> 36 \</stack navigator> 37 \</navigationcontainer> 38 ); 39 }; 40&#x9; 41 // silakan uji layar dan komponen anda perhatikan bahwa aplikasi anda sekarang akan menampilkan layar login pengguna alih alih layar pendaftaran pengguna, karena penempatannya di stacknavigator stacknavigator daftar layar anda akan melihat pesan seperti ini setelah masuk 5 membuat layar beranda dan menangani navigasi setelah masuk, anda umumnya ingin membawa pengguna ke layar beranda aplikasi anda buat layar ini di file utama aplikasi anda app tsx/app js 1 // 2&#x9; 3 // add this new screen function below the userregistrationscreen 4 function userloginscreen() { 5 return ( 6 <> 7 \<statusbar /> 8 \<safeareaview style={styles login container}> 9 \<view style={styles login header}> 10 \<image 11 style={styles login header logo} 12 source={require(' /assets/logo back4app png')} 13 /> 14 \<text style={styles login header text}> 15 \<text style={styles login header text bold}> 16 {'react native on back4app '} 17 \</text> 18 {' user login'} 19 \</text> 20 \</view> 21 \<userlogin /> 22 \</safeareaview> 23 \</> 24 ); 25 } 26&#x9; 27 // 28&#x9; 29 // add the screen as the top one at your stacknavigator 30 const app = () => { 31 return ( 32 \<navigationcontainer> 33 \<stack navigator> 34 \<stack screen name="login" component={userloginscreen} /> 35 \<stack screen name="sign up" component={userregistrationscreen} /> 36 \</stack navigator> 37 \</navigationcontainer> 38 ); 39 }; 40&#x9; 41 // sekarang anda perlu menggunakan ‘react navigation’ untuk menavigasi pengguna setelah dia masuk, tambahkan kode baru ini di dalam userlogin userlogin komponen userlogin js 1 // 2 // add this import 3 import {usenavigation} from '@react navigation/native'; 4&#x9; 5 export const userlogin = () => { 6 // add this to use usenavigation hook 7 const navigation = usenavigation(); 8 9 // 10&#x9; 11 const douserlogin = async function () { 12 const usernamevalue = username; 13 const passwordvalue = password; 14 return await parse user login(usernamevalue, passwordvalue) 15 then(async (loggedinuser) => { 16 alert alert( 17 'success!', 18 `user ${loggedinuser get('username')} has successfully signed in!`, 19 ); 20 const currentuser = await parse user currentasync(); 21 console log(loggedinuser === currentuser); 22 // add this to navigate your home screen; navigation navigate takes 23 // the user to the screen named after the one passed as parameter 24 navigation navigate('home'); 25 return true; 26 }) 27 catch((error) => { 28 alert alert('error!', error message); 29 return false; 30 }); 31 }; 32 // userlogin tsx 1 // 2 // add this import 3 import {usenavigation} from '@react navigation/native'; 4&#x9; 5 export const userlogin fc<{}> = ({}) reactelement => { 6 // add this to use usenavigation hook 7 const navigation = usenavigation(); 8&#x9; 9 // 10 11 const douserlogin = async function () promise\<boolean> { 12 const usernamevalue string = username; 13 const passwordvalue string = password; 14 return await parse user login(usernamevalue, passwordvalue) 15 then(async (loggedinuser parse user) => { 16 alert alert( 17 'success!', 18 `user ${loggedinuser get('username')} has successfully signed in!`, 19 ); 20 const currentuser parse user = await parse user currentasync(); 21 console log(loggedinuser === currentuser); 22 // add this to navigate your home screen; navigation navigate takes 23 // the user to the screen named after the one passed as parameter 24 navigation navigate('home'); 25 return true; 26 }) 27 catch((error object) => { 28 alert alert('error!', error message); 29 return false; 30 }); 31 }; 32&#x9; 33 // anda akan diarahkan ke homescreen homescreen baru anda setelah masuk anda dapat meningkatkan layar ini dengan menambahkan hellouser hellouser komponen yang menunjukkan nama pengguna pengguna saat ini hellouser js 1 import react, {fc, reactelement, useeffect, usestate} from 'react'; 2 import {text} from 'react native'; 3 import parse from 'parse/react native'; 4 import styles from ' /styles'; 5&#x9; 6 export const hellouser = () => { 7 // state variable that will hold username value 8 const \[username, setusername] = usestate(''); 9&#x9; 10 // useeffect is called after the component is initially rendered and 11 // after every other render 12 useeffect(() => { 13 // since the async method parse user currentasync is needed to 14 // retrieve the current user data, you need to declare an async 15 // function here and call it afterwards 16 async function getcurrentuser() { 17 // this condition ensures that username is updated only if needed 18 if (username === '') { 19 const currentuser = await parse user currentasync(); 20 if (currentuser !== null) { 21 setusername(currentuser getusername()); 22 } 23 } 24 } 25 getcurrentuser(); 26 }, \[username]); 27&#x9; 28 // note the condition operator here, so the "hello" text is only 29 // rendered if there is an username value 30 return ( 31 \<view style={styles login wrapper}> 32 \<view style={styles form}> 33 {username !== '' && \<text>{`hello ${username}!`}\</text>} 34 \</view> 35 \</view> 36 ); 37 }; hellouser tsx 1 import react, {fc, reactelement, useeffect, usestate} from 'react'; 2 import {text} from 'react native'; 3 import parse from 'parse/react native'; 4 import styles from ' /styles'; 5&#x9; 6 export const hellouser fc<{}> = ({}) reactelement => { 7 // state variable that will hold username value 8 const \[username, setusername] = usestate(''); 9&#x9; 10 // useeffect is called after the component is initially rendered and 11 // after every other render 12 useeffect(() => { 13 // since the async method parse user currentasync is needed to 14 // retrieve the current user data, you need to declare an async 15 // function here and call it afterwards 16 async function getcurrentuser() { 17 // this condition ensures that username is updated only if needed 18 if (username === '') { 19 const currentuser = await parse user currentasync(); 20 if (currentuser !== null) { 21 setusername(currentuser getusername()); 22 } 23 } 24 } 25 getcurrentuser(); 26 }, \[username]); 27&#x9; 28 // note the condition operator here, so the "hello" text is only 29 // rendered if there is an username value 30 return ( 31 \<view style={styles login wrapper}> 32 \<view style={styles form}> 33 {username !== '' && \<text>{`hello ${username}!`}\</text>} 34 \</view> 35 \</view> 36 ); 37 }; catatan anda dapat melihat lebih baik pada useeffect useeffect hooks di sini https //reactjs org/docs/hooks effect html setelah memanggil komponen ini di dalam homescreen anda, aplikasi anda seharusnya terlihat seperti ini 6 membuat komponen logout komponen userlogout userlogout lebih sederhana daripada login karena metode parse user logout parse user logout tidak memerlukan argumen dan secara otomatis menghapus data currentuser currentuser yang disimpan secara lokal buat komponen ini di direktori root aplikasi anda userlogout js 1 import react, {fc, reactelement} from 'react'; 2 import {alert, text, touchableopacity, view} from 'react native'; 3 import parse from 'parse/react native'; 4 import {usenavigation} from '@react navigation/native'; 5 import {stackactions} from '@react navigation/native'; 6 import styles from ' /styles'; 7&#x9; 8 export const userlogout = () => { 9 const navigation = usenavigation(); 10&#x9; 11 const douserlogout = async function () { 12 return await parse user logout() 13 then(async () => { 14 // to verify that current user is now empty, currentasync can be used 15 const currentuser = await parse user currentasync(); 16 if (currentuser === null) { 17 alert alert('success!', 'no user is logged in anymore!'); 18 } 19 // navigation dispatch calls a navigation action, and poptotop will take 20 // the user back to the very first screen of the stack 21 navigation dispatch(stackactions poptotop()); 22 return true; 23 }) 24 catch((error) => { 25 alert alert('error!', error message); 26 return false; 27 }); 28 }; 29&#x9; 30 return ( 31 \<view style={styles login wrapper}> 32 \<view style={styles form}> 33 \<touchableopacity onpress={() => douserlogout()}> 34 \<view style={styles button}> 35 \<text style={styles button label}>{'logout'}\</text> 36 \</view> 37 \</touchableopacity> 38 \</view> 39 \</view> 40 ); 41 }; userlogout tsx 1 import react, {fc, reactelement} from 'react'; 2 import {alert, text, touchableopacity, view} from 'react native'; 3 import parse from 'parse/react native'; 4 import {usenavigation} from '@react navigation/native'; 5 import {stackactions} from '@react navigation/native'; 6 import styles from ' /styles'; 7&#x9; 8 export const userlogout fc<{}> = ({}) reactelement => { 9 const navigation = usenavigation(); 10&#x9; 11 const douserlogout = async function () promise\<boolean> { 12 return await parse user logout() 13 then(async () => { 14 // to verify that current user is now empty, currentasync can be used 15 const currentuser parse user = await parse user currentasync(); 16 if (currentuser === null) { 17 alert alert('success!', 'no user is logged in anymore!'); 18 } 19 // navigation dispatch calls a navigation action, and poptotop will take 20 // the user back to the very first screen of the stack 21 navigation dispatch(stackactions poptotop()); 22 return true; 23 }) 24 catch((error object) => { 25 alert alert('error!', error message); 26 return false; 27 }); 28 }; 29&#x9; 30 return ( 31 \<view style={styles login wrapper}> 32 \<view style={styles form}> 33 \<touchableopacity onpress={() => douserlogout()}> 34 \<view style={styles button}> 35 \<text style={styles button label}>{'logout'}\</text> 36 \</view> 37 \</touchableopacity> 38 \</view> 39 \</view> 40 ); 41 }; tambahkan komponen baru ini ke homescreen homescreen sehingga anda dapat mengujinya setelah masuk layar beranda aplikasi anda akan terlihat seperti ini sekarang jika anda melakukan logout yang berhasil, anda akan melihat pesan seperti ini saat diarahkan ke userlogin userlogin layar, yang merupakan yang pertama dalam tumpukan navigasi hubungkan userregistration userregistration anda ke tombol pendaftaran di dalam userlogin userlogin layar dan ulangi pola pengalihan yang sama ke aplikasi anda homescreen homescreen ingat untuk membaca melalui dokumen react navigation react navigation untuk menemukan beberapa opsi kustomisasi dan mengontrol setiap aspek navigasi aplikasi anda userlogin js 1 // 2&#x9; 3 export const userlogin = () => { 4 const navigation = usenavigation(); 5&#x9; 6 const \[username, setusername] = usestate(''); 7 const \[password, setpassword] = usestate(''); 8&#x9; 9 const douserlogin = async function () { 10 // note that these values come from state variables that we've declared before 11 const usernamevalue = username; 12 const passwordvalue = password; 13 return await parse user login(usernamevalue, passwordvalue) 14 then(async (loggedinuser) => { 15 // login returns the corresponding parseuser object 16 alert alert( 17 'success!', 18 `user ${loggedinuser get('username')} has successfully signed in!`, 19 ); 20 // to verify that this is in fact the current user, currentasync can be used 21 const currentuser parse user = await parse user currentasync(); 22 console log(loggedinuser === currentuser); 23 // navigation navigate takes the user to the screen named after the one 24 // passed as parameter 25 navigation navigate('home'); 26 return true; 27 }) 28 catch((error) => { 29 // error can be caused by wrong parameters or lack of internet connection 30 alert alert('error!', error message); 31 return false; 32 }); 33 }; 34&#x9; 35 return ( 36 \<view style={styles login wrapper}> 37 \<view style={styles form}> 38 \<textinput 39 style={styles form input} 40 value={username} 41 placeholder={'username'} 42 onchangetext={(text) => setusername(text)} 43 autocapitalize={'none'} 44 keyboardtype={'email address'} 45 /> 46 \<textinput 47 style={styles form input} 48 value={password} 49 placeholder={'password'} 50 securetextentry 51 onchangetext={(text) => setpassword(text)} 52 /> 53 \<touchableopacity onpress={() => douserlogin()}> 54 \<view style={styles button}> 55 \<text style={styles button label}>{'sign in'}\</text> 56 \</view> 57 \</touchableopacity> 58 \</view> 59 \<view style={styles login social}> 60 \<view style={styles login social separator}> 61 \<view style={styles login social separator line} /> 62 \<text style={styles login social separator text}>{'or'}\</text> 63 \<view style={styles login social separator line} /> 64 \</view> 65 \<view style={styles login social buttons}> 66 \<touchableopacity> 67 \<view 68 style={\[ 69 styles login social button, 70 styles login social facebook, 71 ]}> 72 \<image 73 style={styles login social icon} 74 source={require(' /assets/icon facebook png')} 75 /> 76 \</view> 77 \</touchableopacity> 78 \<touchableopacity> 79 \<view style={styles login social button}> 80 \<image 81 style={styles login social icon} 82 source={require(' /assets/icon google png')} 83 /> 84 \</view> 85 \</touchableopacity> 86 \<touchableopacity> 87 \<view style={styles login social button}> 88 \<image 89 style={styles login social icon} 90 source={require(' /assets/icon apple png')} 91 /> 92 \</view> 93 \</touchableopacity> 94 \</view> 95 \</view> 96 <> 97 \<touchableopacity onpress={() => navigation navigate('sign up')}> 98 \<text style={styles login footer text}> 99 {"don't have an account? "} 100 \<text style={styles login footer link}>{'sign up'}\</text> 101 \</text> 102 \</touchableopacity> 103 \</> 104 \</view> 105 ); 106 }; 107&#x9; 108 // userlogin tsx 1 // 2&#x9; 3 export const userlogin fc<{}> = ({}) reactelement => { 4 const navigation = usenavigation(); 5&#x9; 6 const \[username, setusername] = usestate(''); 7 const \[password, setpassword] = usestate(''); 8&#x9; 9 const douserlogin = async function () promise\<boolean> { 10 // note that these values come from state variables that we've declared before 11 const usernamevalue string = username; 12 const passwordvalue string = password; 13 return await parse user login(usernamevalue, passwordvalue) 14 then(async (loggedinuser parse user) => { 15 // login returns the corresponding parseuser object 16 alert alert( 17 'success!', 18 `user ${loggedinuser get('username')} has successfully signed in!`, 19 ); 20 // to verify that this is in fact the current user, currentasync can be used 21 const currentuser parse user = await parse user currentasync(); 22 console log(loggedinuser === currentuser); 23 // navigation navigate takes the user to the screen named after the one 24 // passed as parameter 25 navigation navigate('home'); 26 return true; 27 }) 28 catch((error object) => { 29 // error can be caused by wrong parameters or lack of internet connection 30 alert alert('error!', error message); 31 return false; 32 }); 33 }; 34&#x9; 35 return ( 36 \<view style={styles login wrapper}> 37 \<view style={styles form}> 38 \<textinput 39 style={styles form input} 40 value={username} 41 placeholder={'username'} 42 onchangetext={(text) => setusername(text)} 43 autocapitalize={'none'} 44 keyboardtype={'email address'} 45 /> 46 \<textinput 47 style={styles form input} 48 value={password} 49 placeholder={'password'} 50 securetextentry 51 onchangetext={(text) => setpassword(text)} 52 /> 53 \<touchableopacity onpress={() => douserlogin()}> 54 \<view style={styles button}> 55 \<text style={styles button label}>{'sign in'}\</text> 56 \</view> 57 \</touchableopacity> 58 \</view> 59 \<view style={styles login social}> 60 \<view style={styles login social separator}> 61 \<view style={styles login social separator line} /> 62 \<text style={styles login social separator text}>{'or'}\</text> 63 \<view style={styles login social separator line} /> 64 \</view> 65 \<view style={styles login social buttons}> 66 \<touchableopacity> 67 \<view 68 style={\[ 69 styles login social button, 70 styles login social facebook, 71 ]}> 72 \<image 73 style={styles login social icon} 74 source={require(' /assets/icon facebook png')} 75 /> 76 \</view> 77 \</touchableopacity> 78 \<touchableopacity> 79 \<view style={styles login social button}> 80 \<image 81 style={styles login social icon} 82 source={require(' /assets/icon google png')} 83 /> 84 \</view> 85 \</touchableopacity> 86 \<touchableopacity> 87 \<view style={styles login social button}> 88 \<image 89 style={styles login social icon} 90 source={require(' /assets/icon apple png')} 91 /> 92 \</view> 93 \</touchableopacity> 94 \</view> 95 \</view> 96 <> 97 \<touchableopacity onpress={() => navigation navigate('sign up')}> 98 \<text style={styles login footer text}> 99 {"don't have an account? "} 100 \<text style={styles login footer link}>{'sign up'}\</text> 101 \</text> 102 \</touchableopacity> 103 \</> 104 \</view> 105 ); 106 }; 107&#x9; 108 // userregistration js 1 export const userregistration = () => { 2 const navigation = usenavigation(); 3&#x9; 4 const \[username, setusername] = usestate(''); 5 const \[password, setpassword] = usestate(''); 6&#x9; 7 const dousersignup = async function () { 8 // note that these values come from state variables that we've declared before 9 const usernamevalue = username; 10 const passwordvalue = password; 11 // since the signup method returns a promise, we need to call it using await 12 return await parse user signup(usernamevalue, passwordvalue) 13 then((createduser) => { 14 // parse user signup returns the already created parseuser object if successful 15 alert alert( 16 'success!', 17 `user ${createduser get('username')} was successfully created!`, 18 ); 19 // navigation navigate takes the user to the screen named after the one 20 // passed as parameter 21 navigation navigate('home'); 22 return true; 23 }) 24 catch((error) => { 25 // signup can fail if any parameter is blank or failed an uniqueness check on the server 26 alert alert('error!', error message); 27 return false; 28 }); 29 }; 30&#x9; 31 return ( 32 \<view style={styles login wrapper}> 33 \<view style={styles form}> 34 \<textinput 35 style={styles form input} 36 value={username} 37 placeholder={'username'} 38 onchangetext={(text) => setusername(text)} 39 autocapitalize={'none'} 40 keyboardtype={'email address'} 41 /> 42 \<textinput 43 style={styles form input} 44 value={password} 45 placeholder={'password'} 46 securetextentry 47 onchangetext={(text) => setpassword(text)} 48 /> 49 \<touchableopacity onpress={() => dousersignup()}> 50 \<view style={styles button}> 51 \<text style={styles button label}>{'sign up'}\</text> 52 \</view> 53 \</touchableopacity> 54 \</view> 55 \<view style={styles login social}> 56 \<view style={styles login social separator}> 57 \<view style={styles login social separator line} /> 58 \<text style={styles login social separator text}>{'or'}\</text> 59 \<view style={styles login social separator line} /> 60 \</view> 61 \<view style={styles login social buttons}> 62 \<touchableopacity> 63 \<view 64 style={\[ 65 styles login social button, 66 styles login social facebook, 67 ]}> 68 \<image 69 style={styles login social icon} 70 source={require(' /assets/icon facebook png')} 71 /> 72 \</view> 73 \</touchableopacity> 74 \<touchableopacity> 75 \<view style={styles login social button}> 76 \<image 77 style={styles login social icon} 78 source={require(' /assets/icon google png')} 79 /> 80 \</view> 81 \</touchableopacity> 82 \<touchableopacity> 83 \<view style={styles login social button}> 84 \<image 85 style={styles login social icon} 86 source={require(' /assets/icon apple png')} 87 /> 88 \</view> 89 \</touchableopacity> 90 \</view> 91 \</view> 92 <> 93 \<touchableopacity onpress={() => navigation navigate('login')}> 94 \<text style={styles login footer text}> 95 {'already have an account? '} 96 \<text style={styles login footer link}>{'log in'}\</text> 97 \</text> 98 \</touchableopacity> 99 \</> 100 \</view> 101 ); 102 }; 103&#x9; 104 // userregistration tsx 1 // 2&#x9; 3 export const userregistration fc<{}> = ({}) reactelement => { 4 const navigation = usenavigation(); 5&#x9; 6 const \[username, setusername] = usestate(''); 7 const \[password, setpassword] = usestate(''); 8&#x9; 9 const dousersignup = async function () promise\<boolean> { 10 // note that these values come from state variables that we've declared before 11 const usernamevalue string = username; 12 const passwordvalue string = password; 13 // since the signup method returns a promise, we need to call it using await 14 return await parse user signup(usernamevalue, passwordvalue) 15 then((createduser parse user) => { 16 // parse user signup returns the already created parseuser object if successful 17 alert alert( 18 'success!', 19 `user ${createduser get('username')} was successfully created!`, 20 ); 21 // navigation navigate takes the user to the screen named after the one 22 // passed as parameter 23 navigation navigate('home'); 24 return true; 25 }) 26 catch((error object) => { 27 // signup can fail if any parameter is blank or failed an uniqueness check on the server 28 alert alert('error!', error message); 29 return false; 30 }); 31 }; 32&#x9; 33 return ( 34 \<view style={styles login wrapper}> 35 \<view style={styles form}> 36 \<textinput 37 style={styles form input} 38 value={username} 39 placeholder={'username'} 40 onchangetext={(text) => setusername(text)} 41 autocapitalize={'none'} 42 keyboardtype={'email address'} 43 /> 44 \<textinput 45 style={styles form input} 46 value={password} 47 placeholder={'password'} 48 securetextentry 49 onchangetext={(text) => setpassword(text)} 50 /> 51 \<touchableopacity onpress={() => dousersignup()}> 52 \<view style={styles button}> 53 \<text style={styles button label}>{'sign up'}\</text> 54 \</view> 55 \</touchableopacity> 56 \</view> 57 \<view style={styles login social}> 58 \<view style={styles login social separator}> 59 \<view style={styles login social separator line} /> 60 \<text style={styles login social separator text}>{'or'}\</text> 61 \<view style={styles login social separator line} /> 62 \</view> 63 \<view style={styles login social buttons}> 64 \<touchableopacity> 65 \<view 66 style={\[ 67 styles login social button, 68 styles login social facebook, 69 ]}> 70 \<image 71 style={styles login social icon} 72 source={require(' /assets/icon facebook png')} 73 /> 74 \</view> 75 \</touchableopacity> 76 \<touchableopacity> 77 \<view style={styles login social button}> 78 \<image 79 style={styles login social icon} 80 source={require(' /assets/icon google png')} 81 /> 82 \</view> 83 \</touchableopacity> 84 \<touchableopacity> 85 \<view style={styles login social button}> 86 \<image 87 style={styles login social icon} 88 source={require(' /assets/icon apple png')} 89 /> 90 \</view> 91 \</touchableopacity> 92 \</view> 93 \</view> 94 <> 95 \<touchableopacity onpress={() => navigation navigate('login')}> 96 \<text style={styles login footer text}> 97 {'already have an account? '} 98 \<text style={styles login footer link}>{'log in'}\</text> 99 \</text> 100 \</touchableopacity> 101 \</> 102 \</view> 103 ); 104 }; 105&#x9; 106 // layar login dan pendaftaran anda sekarang seharusnya terlihat seperti ini kesimpulan di akhir panduan ini, anda telah belajar bagaimana cara masuk dan keluar pengguna parse di react native dan untuk menavigasi pengguna melalui aplikasi anda menggunakan react navigation react navigation dalam panduan berikutnya, kami akan menunjukkan kepada anda cara melakukan kueri pengguna yang berguna