Angular 2 pass value to service

I know how to pass data to and from a nested component. But I have a service that gets some data from a REST API. I need the URL in my service to change when I click and run a function. I need to pass an ID to my service and change my URL.

I my component:

showUnitDetails(selectedUnit) {
    this.unitId = selectedUnit;
    this.unitDetails = true;
    this._unitService.getUnit(this.unitId).subscribe(resUnitData => this.unit = resUnitData, err => alert('Error'));
}

In my Service:

getUnit(id: unitId){
    return this._http.get(this._url).map((response: Response) => response.json());
}

But when i save my service I get the error "Cannot find name unitId".

Solution

I made you a quick example showing how to hook up a component and http service together with parameters where you can pass in the id and url.

Module:

import { NgModule } from "@angular/core"

//A Module
@NgModule({
  declarations: [MyComponent],
  providers: [MyService],
})
export class MyModule {}

Component:

import { Component } from "@angular/core"
import { MyService } from 'path-to-service';

//The Component
@Component({
  selector: 'my-component',
  templateUrl: './my-component.component.html',
})

export class MyComponent {
  private id: number;
  private url: string;

  constructor(public myService: MyService) {}

  ngOnInit() {
    this.id = 123;
    this.url = '/api/stuff';

    this.myService
      .getStuff(this.id, this.url)
      .subscribe(response => {
          console.log(response);
        },
        error => {
          console.log(error);
        })
  }
}

Service:

import { Injectable } from '@angular/core';
import { Http } from "@angular/http"

//The Service
@Injectable()
export class MyService {
  constructor(private http: Http) {}

  getStuff(id: number, url: string) {
    const urlWithId = url + id;

    return this.http
      .get(urlWithId)
      .map(res => res.json())
  }
}