ProjectService

import { Component, OnInit } from '@angular/core';
import { MatTableDataSource, MatFormFieldModule, MatInputModule } from '@angular/material';
import { DataSource } from "@angular/cdk/table";
import { ProjectService } from "../services/project.service";
import { Project } from "../models/ProjectModel";
import { Observable } from "rxjs/Observable";
import 'rxjs/add/operator/shareReplay';
import { BehaviorSubject } from 'rxjs/BehaviorSubject';

@Component({
  selector: 'app-projects',
  templateUrl: './projects.component.html',
  styleUrls: ['./projects.component.css']
})

export class ProjectsComponent implements OnInit {

  private dataSource = new ProjectDataSource(this.projectService);
  displayedColumns = ['project_name','project_description', 'project_status'];

  applyFilter(filterValue: string) {
    console.log(filterValue);
    filterValue = filterValue.trim(); // Remove whitespace
    filterValue = filterValue.toLowerCase(); // MatTableDataSource defaults to lowercase matches
    this.dataSource.filter = filterValue;
    console.log(this.dataSource);
  }


  constructor(private projectService: ProjectService) {
    //this.projectService.getAllProjects().subscribe(e=> e.map(b => this.projectArray.push(b)));
  }

  ngOnInit() {}
}

export class ProjectDataSource extends MatTableDataSource<any>{
  ProjectObservable = this.projectService.getAllProjects();
  ProjectSubject = new BehaviorSubject<Project[]>([]);

  constructor(private projectService: ProjectService){
    super();
  }

  connect(): BehaviorSubject<Project[]>{
    this.ProjectObservable
      .subscribe(e => this.ProjectSubject.next(e));
    return this.ProjectSubject;
  }

  disconnect(){ }
}


#########################

import { Injectable } from '@angular/core';
import { HttpClient } from "@angular/common/http";
import { Project } from "../models/ProjectModel";
import { Observable } from "rxjs/Observable";

@Injectable()
export class ProjectService {
  readonly ALL_PROJECT_JSON = "http://localhost:8080/api/projects/read";
  constructor(private http: HttpClient) { }

  getAllProjects(): Observable<Project[]>{
    return this.http.get<Project[]>(this.ALL_PROJECT_JSON);
  }
}