如何解决“错误：未捕获（承诺）：错误：没有供应商”在Ionic 3中的错误

我正在学习Ionic 3，并且在尝试制作自定义验证程序时遇到此错误，该验证程序检查唯一用户名。我已尽力，但无法解决此问题。如何解决“错误：未捕获（承诺）：错误：没有供应商”在Ionic 3中的错误

CustomValidators.ts

import { Directive, Input } from '@angular/core'; 

import { FormControl, Validator, AbstractControl } from '@angular/forms'; 
import { Http, Response, Headers, RequestOptions } from '@angular/http'; 
import {Observable} from 'rxjs/Rx'; 

export class CustomValidators { 


    constructor(public http: Http){} 

     public hasUniqueEmail(
     control: FormControl, 
    ){ 

     return this.http.get('assets/users.json') 
     .map(res => res.json()) 
     .catch((error:any) => Observable.throw(error.json().error || 'Server error')); 

     } 


}

signup.ts

import { Component } from '@angular/core'; 
import { IonicPage, NavController, NavParams } from 'ionic-angular'; 
import { FormBuilder, FormGroup, Validators } from '@angular/forms'; 
import { CustomValidators } from '../../components/CustomValidators'; 

/** 
* Generated class for the SignupPage page. 
* 
* See http://ionicframework.com/docs/components/#navigation for more info 
* on Ionic pages and navigation. 
*/ 


@IonicPage() 

@Component({ 
    selector: 'page-signup', 
    templateUrl: 'signup.html', 
}) 


export class SignupPage { 

    private sform : FormGroup; 

    constructor(
     private formBuilder: FormBuilder, 
     private myValidator: CustomValidators, 
    ){ 

    this.sform = this.formBuilder.group({ 
     name: ['', Validators.compose([Validators.maxLength(30), Validators.pattern('[a-zA-Z ]*'), Validators.required])], 
     email: ['', Validators.compose([Validators.email,this.myValidator.hasUniqueEmail])], 
     password: ['',Validators.required                        ], 
    }); 

    } 


    logForm() { 

    } 


}

这是我得到的错误：

"Uncaught (in promise): Error: No provider for CustomValidators! 
Error 
    at Error (native) 
    at injectionError (http://localhost:8100/build/main.js:1583:86) 
    at noProviderError (http://localhost:8100/build/main.js:1621:12) 
    at ReflectiveInjector_._throwOrNull (http://localhost:8100/build/main.js:3122:19) 
    at ReflectiveInjector_._getByKeyDefault (http://localhost:8100/build/main.js:3161:25) 
    at ReflectiveInjector_._getByKey (http://localhost:8100/build/main.js:3093:25) 
    at ReflectiveInjector_.get (http://localhost:8100/build/main.js:2962:21) 
    at NgModuleInjector.get (http://localhost:8100/build/main.js:3909:52) 
    at resolveDep (http://localhost:8100/build/main.js:11369:45) 
    at createClass (http://localhost:8100/build/main.js:11225:91)"

来源

2017-06-16 J Snow

CustomValidators是一个组件，一个服务，一个管道，类应该表示什么？ – Baruch

您需要将提供程序添加到NgModule ，即module.ts在供应商下，

providers: [ 
    CustomValidators 
]

来源

2017-06-16 04:44:00 Sajeetharan

我已经尝试过，但得到了这个错误！ “未捕获的错误：无法解析所有参数” 你们是否知道涵盖angular4中所有这些主题的任何教程？ –

然后您需要使用@inject并在构造函数中使用它 – Sajeetharan

从我能看到你错过了两件事情

1）无装饰的类，你要导入Directive但从来没有使用它

import { Directive } from '@angular/core'; 

@Directive({ 
    name: 'directive-name' 
}) 
export class CustomValidators { 
    //... 
}

2）有没有在进口NgModule

import { CustomValidators } from 'path/to/file'; 

@NgModule({ 
    //... 
    providers: [ 
    CustomValidators 
    ] 
})

来源

2017-06-16 04:46:25 Baruch

如何解决“错误：未捕获（承诺）：错误：没有供应商”在Ionic 3中的错误

回答

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