Ionic 如何将变量传递给 firebase equalTo 方法

Question

我已经设法从 firebase.problem 中获取数据，但是当我要根据 id 过滤数据时它不起作用。

import { Component, OnInit } from '@angular/core';
import { ActivatedRoute } from '@angular/router';
import { AngularFireDatabase, AngularFireList ,} from 'angularfire2/database';

import { Observable } from 'rxjs'
import { query } from '@angular/core/src/render3';
import { Key } from 'protractor';


class postview {
  constructor(public title) { }
}

@Component({
  selector: 'app-news-view',
  templateUrl: './news-view.page.html',
  styleUrls: ['./news-view.page.scss'],
})
export class NewsViewPage implements OnInit {

  id: string;



  public books: AngularFireList<postview[]>;
  itemlol: Observable<any>;
  posts: Observable<any[]>;

    constructor(private route: ActivatedRoute  , db: AngularFireDatabase) {
      let idp :string = this.id;
      this.posts = db.list('Posts' ,ref => {
        return ref.orderByChild('Post_Id').equalTo(idp)       
            }).valueChanges();

           // this.itemlol= db.object('Posts').valueChanges();
      }


  ngOnInit() {
    this.id = this.route.snapshot.paramMap.get('id');



    console.log(this.id);

    console.log(this.posts);


  }



}

在 return ref.orderByChild('Post_Id').equalTo(idp) 部分中，我需要在 equalTo() 中传递变量。它应该根据用户说明更改

示例

equalTo(01)
equalTo(02)

这是我的 firebase 数据库：

Answer 1

在 ngOnInit 之前调用构造函数，因此 this.id 的值在查询时将是未定义的。

你应该在构造函数中获取参数

 this.id = this.route.snapshot.paramMap.get('id');
 let idp :string = this.id;
 this.posts = db.list('Posts' ,ref =>  ref.orderByChild('Post_Id').equalTo(idp)     ).valueChanges();

Ionic 如何将变量传递给 firebase equalTo 方法

Ionic How to Pass variable to firebase equalTo method

javascript

firebase

ionic-framework

firebase-realtime-database

angularfire2