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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"关于组件构造方法解析参数(Service参数)失败的问题,求大神指教!","articleBody":"错误日志如下:\r\n        (SystemJS) Can't resolve all parameters for RegisterComponent: (?, UserService, Router).\r\n\r\n组件:RegisterComponent 部分代码如下:\r\n        export class RegisterComponent implements OnInit {\r\n        form:FormGroup;\r\n       registered = false;\r\n       fields:FieldBase\u003cany\u003e[] = [];\r\n      alert:any = {msg:'注册成功',type:'success',closable:true};\r\n\r\n    constructor(\r\n        private registerService:RegisterService,\r\n        private userService:UserService,\r\n        private route:Router\r\n        ) {\r\n            this.fields = registerService.getFields();\r\n         }\r\n\r\nRegisterService.ts的代码如下:\r\n import { Injectable } from '@angular/core';\r\nimport { Http,Headers } from '@angular/http';\r\nimport { FormControl,Validators,FormGroup } from '@angular/forms';\r\n\r\nimport { FieldBase,FieldText,FieldValidators} from '../../user/shared/index';\r\nimport { SITE_HOST_URL } from '../../shared/index';\r\n\r\n@Injectable()\r\nexport class RegisterService {\r\n\r\n    private registerUrl = `${SITE_HOST_URL}user/add`;\r\n\r\n    constructor(private http:Http) { }\r\n\r\n    getFields(){\r\n        let fields:FieldBase\u003cany\u003e[]=[\r\n            new FieldText({\r\n                key:'username',\r\n                lable:'用户名',\r\n                value:'',\r\n                required:true,\r\n                pattern:'username',\r\n                order:1\r\n            }),\r\n            new FieldText({\r\n                key:'password',\r\n                lable:'密码',\r\n                type:'password',\r\n                value:'',\r\n                required:true,\r\n                pattern:'password',\r\n                order:2\r\n            }),\r\n        ];\r\n       return fields.sort((a,b)=\u003ea.order - b.order); \r\n    }\r\n    \r\n    toFormGroup(fields:FieldBase\u003cany\u003e[]){\r\n        let group :any = {};\r\n        fields.forEach(field=\u003e{\r\n            group[field.key]=\r\n                field.pattern?\r\n                new FormControl(field.value||'',(\u003cany\u003eFieldValidators)[field.pattern]):\r\n                field.required?\r\n                new FormControl(field.value||'',Validators.required):\r\n                new FormControl(field.value||'');\r\n        });\r\n        return new FormGroup(group);\r\n    }\r\n\r\n    addUser(data:Object){\r\n        let body = JSON.stringify(data);\r\n        let headers = new Headers();\r\n        headers.append('Content-Type','application/json');\r\n        return this.http.post(this.registerUrl,body,{headers});\r\n    }\r\n}\r\n\r\n\r\n\r\n1.组件中私有属性服务:RegisterService已在父模块中注入了.\r\n2.如果注释掉构造方法中的私有属性private registerService:RegisterService,错误会消失.\r\n3.如果注释掉RegisterService中的toFormGroup(),getFields()方法,则错误会消失.\r\n\r\n\r\n","author":{"url":"https://github.com/dukehq","@type":"Person","name":"dukehq"},"datePublished":"2017-06-12T01:59:14.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":3},"url":"https://github.com/40/issues/issues/40"}