服务中注入的服务未定义
[英]Service injected in service is undefined
问题描述
I have two services, where first is injected in second service, in this way: 
我有两个服务，以这种方式将第一个服务注入第二个服务：
rule.service.ts rule.service.ts
@Injectable()
export class RuleService {
constructor(
private _resourceService: ResourceService
){}
someMethod(url: string) {
this._resourceService.getData(url).then((res) => {
console.log(res);
}
}
}
resource.service.ts resource.service.ts
@Injectable()
export class ResourceService {
constructor(
http: Http
) { }
public getData(url?: string): Promise<T> {
//some code
}
}
called service jQuery :( 称为服务 jQuery :(
private run(input: any, a_parameters: any) {
$("select[name='" + a_parameters[0] + "']").change(function(e: any) {
return new Promise((resolve) => {
let array: any[] = [];
this._resourceService.getData(a_parameters[1]).then(() => {
let result: any;
...
but when I trying call someMethod from RuleService , I get this console error: 但是当我尝试从RuleService调用someMethod时，出现以下控制台错误：
EXCEPTION: Uncaught (in promise): TypeError: Cannot read property 'getData' of undefined TypeError: Cannot read property 'getData' of undefined at eval (eval at ( http://localhost:8099/app.js:457:2 ), :210:39) at new ZoneAwarePromise (eval at ( http://localhost:8099/polyfills.js:2304:2 ), :695:29) at HTMLSelectElement.eval (eval at ( http://localhost:8099/app.js:457:2 ), :208:20) at HTMLSelectElement.dispatch ( http://cdn.execon.pl/resources/GRM/js/libs/jquery-1.11.0.min.js:3:8066 ) at HTMLSelectElement.r.handle ( http://cdn.execon.pl/resources/GRM/js/libs/jquery-1.11.0.min.js:3:4767 ) at ZoneDelegate.invokeTask (eval at ( http://localhost:8099/polyfills.js:2304:2 ), :363:31) at Object.onInvokeTask (eval at ( http://localhost:8099/vendor.js:101:2 ), :3971:41) at ZoneDelegate.invokeTask (eval at ( http://localhost:8099/polyfills.js:2304:2 ), :362:36) at Zone.runTask (eval at ( http://localhost:8099/polyfills.js:2304:2 ), :166:47) at HTMLSelectElement.ZoneTask.invoke (eval at ( http://lo
Anyone can tell me, what I do wrong? 谁能告诉我，我做错了什么？ How can I correct implement service in service? 如何在服务中正确实施服务？
1 个解决方案
解决方案1
3 已采纳 2017-03-16 20:43:03
You need to use arrow function to retain this 您需要使用箭头功能来保留this
$("select[name='" + a_parameters[0] + "']")
.change((e: any) => { // <== arrow function instead of FE(function expression)
return new Promise((resolve) => {
let array: any[] = [];
this._resourceService.getData(a_parameters[1]).then(() => {
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