在我的离子应用程序运行期间出现此错误。我试图实现Ionic“ Email Composer”库以从客户端发送电子邮件，请参考此链接以了解我所关注的代码；[ https://ionicframework.com/docs/native/email-composer][1]。错误的流程是当我测试应用程序时，我按下了触发“ LoadingDialog”功能的按钮，该功能触发了发生错误的“ SendEmail”功能。我不确定如何解决此错误，但我认为这与我尚不了解的Promise的语法有关。感谢您提供任何帮助！
this.emailComposer.isAvailable（）。then（（available：boolean）=> {// <<<<<<<<这是home.page.ts文件中的221行，它出现在错误中
this.SendEmail（）; // <<<<<<<<这是home.page.ts文件中的109行
ERROR Error: Uncaught (in promise): TypeError: Cannot read property 'then' of undefined TypeError: Cannot read property 'then' of undefined
at HomePage.SendEmail (home.page.ts:221)
at HomePage.<anonymous> (home.page.ts:109)
at Generator.next (<anonymous>)
at fulfilled (tslib.es6.js:70)
at ZoneDelegate.invoke (zone-evergreen.js:359)
at Object.onInvoke (core.js:34201)
at ZoneDelegate.invoke (zone-evergreen.js:358)
at Zone.run (zone-evergreen.js:124)
at zone-evergreen.js:855
at ZoneDelegate.invokeTask (zone-evergreen.js:391)
at resolvePromise (zone-evergreen.js:797)
at zone-evergreen.js:707
at fulfilled (tslib.es6.js:70)
at ZoneDelegate.invoke (zone-evergreen.js:359)
at Object.onInvoke (core.js:34201)
at ZoneDelegate.invoke (zone-evergreen.js:358)
at Zone.run (zone-evergreen.js:124)
at zone-evergreen.js:855
at ZoneDelegate.invokeTask (zone-evergreen.js:391)
at Object.onInvokeTask (core.js:34182)
import { EmailComposer } from '@ionic-native/email-composer/ngx';
export class HomePage {
constructor(private http: Http, public loadingController: LoadingController,
public alertController: AlertController,
private emailComposer: EmailComposer) {
//constructor
}
async LoadingDialog(httpformdata) {//loading circle symbol
const loading = await this.loadingController.create({
message: 'Please wait...',
duration: null
});
this.loading = loading;
this.loading.present();
console.log('ion dialog created.');
/*** SendEmail ***/
this.SendEmail(); //<<<<<<<< THIS IS LINE 109 IN home.page.ts file
/*** GET REQUEST ***/
this.GET_request(httpformdata);
/*** POST REQUEST ***/
//this.POST_request(httpformdata);
console.log('request made in async.');
//this.loading.dismiss();
//console.log('ion dialog dismissed.');
const { role, data } = await loading.onDidDismiss();
console.log('Loading dismissed!');
}
async RegularAlert(the_header: String, the_message: String) {//customized alert() dialog
const alert = await this.alertController.create({
header: '' + the_header,
message: '' + the_message,
buttons: ['OK']
});
await alert.present();
return alert.getAttribute("header");
}
SendEmail(){
this.emailComposer.isAvailable().then((available: boolean) =>{ //<<<<<<<< THIS IS LINE 221 IN home.page.ts file
if(available) {
//Now we know we can send
this.RegularAlert("testing the isAvailable().then", "available is true");//print a debug message to test functionality of
let email = {
to:'[email protected]',
cc: '[email protected]',
bcc: [],
attachments: [],
subject: 'Cordova Icons',
body: 'How are you? Nice greetings from Leipzig',
isHtml: false
}
// Send a text message using default options
this.emailComposer.open(email);
}
else{
this.RegularAlert("testing the isAvailable().then", "available is false");
}
});
}
}
发生此错误的原因是，我没有在模拟器或Android手机中运行该应用程序，因为Cordova库仅与移动操作系统（如Android OS）一起运行。您需要的最低要求是：
如果（this.platform.is（'cordova'））{//在此处运行电子邮件编写器代码}
我在Android手机上运行代码后，此代码为我工作了：
if (this.platform.is('cordova')){//use this for android,iOS,Windows-Mobile,etc){
try {
this.emailComposer.isAvailable().then((available: boolean) =>{
if(available) {
//Now we know we can send
let email = {
to: '[email protected]',
cc: '[email protected]',
bcc: [],
attachments: [],
subject: 'Cordova Icons',
body: 'How are you? Nice greetings from Leipzig',
isHtml: false
}//email object close
//Send a text message using default options
this.emailComposer.open(email);//opens user prompt to use third party email app with the email message above.
}//if close
else{
console.log("Rare Error inside of the promise returned by the emailComposer.isAvailable()", "promise error");//TEST PRINT
}
});
} catch(e){
//catches the "this.emailComposer.isAvailable()" variable if the email composer plugin is not available on the installed phone
}
}//if this.platform.is close
else{
console.log("Platform is not cordova/mobile","You are running in browser, this.emailComposer.isAvailable() is undefined.");//TEST PRINT
}//else close
这是电子邮件编辑器的源代码：https : //ionicframework.com/docs/native/email-composer
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