承诺在 javascript 中解决并拒绝

Question

我正在尝试在 NativeScript 上构建一个移动应用程序，我在其中创建了一个 class 用于授权，它具有 login() 函数，该函数具有以下代码：

export default class NitsEditorAuth {
    //Finding logged-in user.
    isLoggedIn() {
        return store.getters.access_token ? true : false;
    }
    //For Login user
    login(user) {
        const postData = {
            grant_type: 'password',
            username: user.email,
            password: user.password,
            client_id: clientId,
            client_secret: clientSecret,
            scope: '',
            provider: provider
        }
        const authUser = {}
        axios.post(authUrl, postData).then(response => {
            if(response.status === 200)
            {
                authUser.access_token = response.data.access_token;
                authUser.refresh_token = response.data.refresh_token;
                axios.get(apiUrl + 'user/log', {headers: getHeader()}).then(response => {
                    if(response.status === 200){
                        authUser.email = response.data.email;
                        authUser.first_name = response.data.first_name;
                        authUser.last_name = response.data.last_name;
                        authUser.userRole = response.data.role;
                        store.commit('save', authUser);
                        return new Promise(function (resolve, reject) {
                            resolve('Login successful')
                        });
                    }
                })
            }
        })
        .catch((err) => {
            if(err.response.status === 401){
//                this.error = err.response.data.message
                return new Promise(function (resolve, reject) {
                    reject('Validation error')
                });
            }
            else
                return new Promise(function (resolve, reject) {
                    reject('Something went wrong')
                });
        })
    }

}

我将这个 class 包含在我的 main.js 文件中：

const nitsEditorAuth = new NitsEditorAuth();
Vue.prototype.$nitsEditorAuth = nitsEditorAuth;

我在 Vue-methods 中调用此函数，例如：

login() {
    this.$nitsEditorAuth
        .login(this.user)
        .then(() => {
           this.processing = false;
           this.$navigateTo(Home, { clearHistory: true });
        })
        .catch(() => {
           this.processing = false;
           this.alert(
              "Unfortunately we could not find your account."                   
           );
        });
},

但我收到错误说明：

TypeError: Cannot read property 'then' of undefined. Frame: function:'login'

帮我解决这个问题。谢谢。

Answer 1

您没有返回 axios 在您的 login 方法中返回的承诺（以及对 axios.get(apiUrl + 'user/log',

的内部调用，从而破坏了承诺链

return axios.post(authUrl...

来自 then handlers of Promises are chained 的

Return 值，请参阅此示例：

// a here points to a promise that will resolve to "Just the 2 of us"
const a = Promise.resolve(1)
  .then(val => val + val)
  .then(val => `Just the ${val} of us`);

a.then(val => console.log(val))

Answer 2

简单的解决方法就是在函数外包装一个 promise。并删除其余部分。例如。

javascript node.js vue.js nativescript nativescript-vue
I'm trying to build a mobile application on NativeScript where I've created a class for authorization which has a login() function which has following codes:

export default class NitsEditorAuth {
    //Finding logged-in user.
    isLoggedIn() {
        return store.getters.access_token ? true : false;
    }
    //For Login user
    login(user) {
        const postData = {
            grant_type: 'password',
            username: user.email,
            password: user.password,
            client_id: clientId,
            client_secret: clientSecret,
            scope: '',
            provider: provider
        }
return new Promise(function (resolve, reject) {
        const authUser = {}
        axios.post(authUrl, postData).then(response => {
            if(response.status === 200)
            {
                authUser.access_token = response.data.access_token;
                authUser.refresh_token = response.data.refresh_token;
                axios.get(apiUrl + 'user/log', {headers: getHeader()}).then(response => {
                    if(response.status === 200){
                        authUser.email = response.data.email;
                        authUser.first_name = response.data.first_name;
                        authUser.last_name = response.data.last_name;
                        authUser.userRole = response.data.role;
                        store.commit('save', authUser);

                            resolve('Login successful')

                    }
                })
            }
        })
        .catch((err) => {
            if(err.response.status === 401){
//                this.error = err.response.data.message

                    reject('Validation error')

            }
            else

                    reject('Something went wrong')
        })
})
    }

Answer 3

在您的登录功能中，您在 axios post 调用中 return 进行了一个本质上异步的承诺。您应该 return 承诺的功能不是 returning 任何东西。所以你可以参考下面的代码。

login() {
  let promise = new Promise(function(resolve, reject) {

  // your post call (dummy data) 
  axios.post(authUrl, postData).then(response => {
        if(response.status === 200) {
           resolve('foo');
        } else {
           reject('Login successful');
        }
  });

  return promise;
}

希望对您有所帮助。

Answer 4

您可以使用 async/await 模式。

async login(user) {
  const postData = {
    grant_type: 'password',
    username: user.email,
    password: user.password,
    client_id: clientId,
    client_secret: clientSecret,
    scope: '',
    provider: provider
  };

  const authUser = {};
  try {
    const postResponse = await axios.post(authUrl, postData);
    if (postResponse.status === 200) {
      authUser.access_token = response.data.access_token;
      authUser.refresh_token = response.data.refresh_token;
      const response = await axios.get(apiUrl + 'user/log', {headers: getHeader()});
      if (response.status === 200) {
        authUser.email = response.data.email;
        authUser.first_name = response.data.first_name;
        authUser.last_name = response.data.last_name;
        authUser.userRole = response.data.role;
        store.commit('save', authUser);
        return 'Login successful';
      }
    }

    return 'Validation error';
  }  
  catch(err) {
    if (err.response.status === 401){
      return 'Validation error';
    }
    return 'Something went wrong';
  }
}

承诺在 javascript 中解决并拒绝

Promise resolve and reject in javascript

javascript

node.js

vue.js

nativescript

nativescript-vue