[英]Angular queryParamMap is empty, then populated
我在我的應用程序中創建了一個新模塊,這樣我就可以分離不需要通信的部分,並創建了一個 new.module.ts 及其自己的路由模塊和組件:
new-routing.module.ts
:
const exportRoutes: Routes = [
{
path: 'export',
component: ExportsComponent
}
]
@NgModule({
imports: [RouterModule.forRoot(exportRoutes)],
exports: [RouterModule]
})
export class ExportRoutingModule {}
new.module.ts
:
import { Router } from '@angular/router'
import { BrowserModule } from '@angular/platform-browser'
// Routing Module
import { NewRoutingModule } from './new-routing.module'
@NgModule({
imports: [..., ExportRoutingModule, ...],
declarations: [ExportsComponent],
bootstrap: [ExportsComponent]
})
我有一個簡單的index.html
:
<body class="app">
<router-outlet></router-outlet> // outlet is here because I read that I needed it to be able to use activated route, I actually just want the query params
</body>
最后,問題出在哪里,我的組件:
export class MyComponent implements OnInit {
constructor(private activatedRoute: ActivatedRoute) {}
ngOnInit() {this.activatedRoute.queryParamMap.subscribe(
(params: ParamMap) => console.log(params)
// Do stuff with params => error)}
當我在我的控制台中導航到http://localhost:4200/export?firstParam=1.00,2.00,3.00
時, params
被記錄兩次,一次為空,一次填充如下:
ParamsAsMap {params: {…}}
keys:(...) // empty
params:{} // empty
core.js:3565 Angular is running in the development mode. Call enableProdMode() to enable the production mode.
ParamsAsMap {params: {…}}
keys:Array(3)
params:{firstParam: "1.00,2.00,3.00", secondParam: "bla"}
這導致我的組件拋出錯誤,因為我需要這些參數來顯示我的組件,並且第一次登錄時它們是空的,因此:
activatedRoute
;我只想要來自的查詢參數我的 url謝謝你的幫助
我將提供2個解決此問題的方法,首先,使用skip
運算符:
由於Activated Route是一個BehaviorSubject,所以首先我們得到一個空值,然后是實際的查詢參數,這樣我們就可以跳過第一個值:
(注意,這個解決方案使用lettable運算符,因此使用pipe()
,如果你沒有使用lettable運算符,你可以像對待任何其他rxjs運算符一樣鏈接它: .skip(1)
export class MyComponent implements OnInit {
constructor(private activatedRoute: ActivatedRoute) {}
ngOnInit()
{this.activatedRoute.queryParamMap.pipe(skip(1)).subscribe(
(params: ParamMap) => console.log(params)}
第二種解決方案,使用常規的javascript函數來檢索params:
ngOnInit() {
const token = this.getParameterByName('access_token');
console.log(token);
}
getParameterByName(name: any) {
let url = window.location.href;
name = name.replace(/[[]]/g, "\$&");
var regex = new RegExp("[?&]" + name + "(=([^&#]*)|&|#|$)"),
results = regex.exec(url);
if (!results) return null;
if (!results[2]) return '';
return decodeURIComponent(results[2].replace(/+/g, " "));
}
我將指出這個原始代碼的stackoverflow答案
當沒有查詢參數並且我們需要檢測它時,@Lakston 接受的答案沒有考慮流程。 經過一番努力后,我為我們這些使用 SSR(服務器端渲染,意味着我們沒有可用的瀏覽器全局對象)並且需要檢測無查詢參數場景的人找到了一個真正的解決方案。
import { Location } from '@angular/common';
----------------------------------------------------------
constructor(private location: Location)
----------------------------------------------------------
let questionIndex = this.location.path().indexOf('?');
questionIndex = questionIndex === -1 ? Infinity : questionIndex;
const queryParams = (<any>Object).fromEntries(this.location.path().substr(questionIndex + 1).split('&').filter(str => str).map(el => el.split('=')));
所有積分歸功於 YugasVasyl,他將此答案發布在: https://github.com/angular/angular/issues/12157
我已經在我的項目中測試過它並且它有效。 祝福...
我認為問題是您使用ExportsComponent
進行引導:
@NgModule({
...
bootstrap: [ExportsComponent]
})
您在此處指定的組件在應用程序啟動時使用,因此它的早期調用ngOnInit
。
你可以做的是有一個單獨的組件用於bootstrapping和單獨的ExportComponent
,這是一個例子(參見實時版本 ):
import { bootstrap } from '@angular/platform-browser-dynamic';
import { RouterModule, Router, Routes, ActivatedRoute } from '@angular/router';
import { NgModule, Component, OnInit } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { platformBrowserDynamic } from '@angular/platform-browser-dynamic';
@Component({
selector: 'my-app',
template: `
<nav class="rbe-plunk-nav">
<ul>
<li> <a [routerLink]="['/']">Homepage</a> </li>
<li> <a [routerLink]="['/about']">Export</a> </li>
</ul>
</nav>
<main>
<router-outlet></router-outlet>
<!-- The router will put the content here, right after the outlet -->
</main>
`
})
export class AppComponent { }
@Component({
selector: 'home',
template: '<h1>Home: </h1>'
})
export class HomeComponent { }
@Component({
selector: 'export',
template: '<h1>Export: </h1>'
})
export class ExportComponent implements OnInit {
constructor(private route: ActivatedRoute) {}
ngOnInit() {
this.route.queryParamMap.subscribe(paramMap => {
console.log("Export: ");
console.log(paramMap);
});
}
}
export const routes: Routes = [
{ path: '', component: HomeComponent },
{ path: 'about', component: ExportComponent }
];
@NgModule({
imports: [
BrowserModule,
RouterModule.forRoot(
routes,
{ /*enableTracing: true*/ }
)
],
declarations: [
AppComponent,
HomeComponent,
ExportComponent
],
bootstrap: [ AppComponent ]
})
export class AppModule {
// Diagnostic only: inspect router configuration
constructor(router: Router) {
console.log('Routes: ', JSON.stringify(router.config, undefined, 2));
}
}
platformBrowserDynamic().bootstrapModule(AppModule);
Url: http://localhost:4200/licenca-filtro?param=60¶m2=50
組件.ts
constructor( private route: ActivatedRoute, ) { const param1 = this.route.queryParams['value']['param']; const param2 = this.route.queryParams['value']['param2']; console.log(param1, param2); }
出局:60 50
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