Angular2 ag-grid数据源

我试图让一个ag-grid数据源在angular2中工作，虽然我感觉我几乎在那里我无法用我目前对angular / typescript的知识解决以下问题 .

问题是我有一个名为returnRows的函数，它完全正常（参见testdata变量） . 但是当我尝试在datasource.getRows中调用它时，我得到以下异常：TypeError：this.returnRows不是PagetestComponent @ 2：2中的[gridOptions]中的函数 . 最后，我想用一个从api获取数据的服务替换该函数 .

这是我的component.ts代码：

import {Component, OnInit} from 'angular2/core';
import {RouteParams} from 'angular2/router';

import {AgGridNg2} from 'ag-grid-ng2/main';
import {GridOptions} from 'ag-grid/main';

import {PagetestService} from '..//services/pagetest.service';

@Component({
  selector: 'sample',
  templateUrl:'/static/app/pagetest/components/pagetest.component.html',
  directives: [AgGridNg2],
  providers: [PagetestService]
})

export class PagetestComponent implements OnInit{
    public gridOptions: GridOptions;
    private columnDefs: any[];
    private testdata: any[];

    constructor(
        public _routeParams: RouteParams,
        public _variantsService: PagetestService) {
    }

    ngOnInit(){
        this.columnDefs = [
          {headerName: "ID", field: "_id",},
          {headerName: "CHR", field: "chr"},
          {headerName: "POS", field: "pos"},
          {headerName: "REF", field: "ref"},
          {headerName: "ALT", field: "alt"},
        ];
        this.gridOptions = <GridOptions>{};
        this.gridOptions.datasource = this.dataSource;
        this.testdata = this.returnRows();
    }

    dataSource = {
        //rowCount : -1,
        pageSize: 1,
        overflowSize: 100,

        getRows: function(params: any){
            console.log(params)
            //var rowData = [
                //{"chr": "1", "_id": "1-22848972-A-C", "ref": "A", "pos": 22848972, "alt": "C"},
                //{"chr": "1", "_id": "1-33133968-T-C", "ref": "T", "pos": 33133968, "alt": "C"}
            //]
            rowData = this.returnRows();
            var rowsThisPage = rowData.slice(params.startRow, params.endRow);
            console.log(rowsThisPage)
            var lastRow = -1;
            params.successCallback(rowsThisPage, lastRow);
        }
    }

    returnRows(){
        var rowData = [
            {"chr": "1", "_id": "1-22848972-A-C", "ref": "A", "pos": 22848972, "alt": "C"},
            {"chr": "1", "_id": "1-33133968-T-C", "ref": "T", "pos": 33133968, "alt": "C"}
        ]
        return rowData
    }
}

更新，感谢@Dinistro回答我的初步问题 .

更新的代码（部分）：

getRows: (params: any) => {
    var rowData = this.returnRows();
    var rowsThisPage = rowData.slice(params.startRow, params.endRow);
    var lastRow = -1;
    //if (rowData.length <= params.endRow) {
        //lastRow = rowData.length;
    //}
    // call the success callback
    params.successCallback(rowsThisPage, lastRow);
}

并为returnRows函数添加了服务 .

returnRows() {
    var rowData: any;
    this._variantsService.getVariants().subscribe(
        variants => rowData = variants
    );
    console.log(rowData)
    return rowData;
}

现在这个错误的结果如下：TypeError：在PagetestComponent @ 2：2中的[gridOptions]中未定义rowData . 可能是一个类似的错误，但我不能让它工作 .

pagetest.component.html

<h1>Pagetest</h1>
<ag-grid-ng2 #agGrid style="width: 100%; height: 350px;" class="ag-fresh"
  [gridOptions]="gridOptions"
  [columnDefs]="columnDefs"

  rowModelType = "pagination"

  enableColResize>
</ag-grid-ng2>

pagetest.service.ts

import {Injectable} from 'angular2/core';
import {Http, Response} from 'angular2/http';
import {Observable} from 'rxjs/Observable';

@Injectable()
export class PagetestService {
  constructor (private http: Http) {}

  private _variantsUrl = '/api/variant/';  // URL to web api

  getVariants () {
    return this.http.get(this._variantsUrl)
                    .map(res => res.json())
                    .catch(this.handleError);
  }
  private handleError (error: Response) {
    console.error(error);
    return Observable.throw(error.json().error || 'Server error');
  }

}