using "POST" instead of "GET" for pagination how to add extra parameters in body ?

I've checked the document and source code for pagination implementation (advanced-example-server.component.ts). And found that the ServerDataSource it used had only implemented pagination via HTTP GET (_sort, _limit, _page, etc parameters expose in URL)..... as my currently project worked on required to use POST to send front-end parameters to back-end Restful APIs using extends to HTTP post call implement, I don't know how to add the extra parameters in pagination request. I Need To pass the request_server to extendsplugin.ts
[](https://www.pipiscrew.com/2019/06/from-wenzhixin-bootstrap-table-to-angular-akveo-ng2-smart-table/)
```
import { Observable } from 'rxjs/internal/Observable';
import { ServerDataSource } from 'ng2-smart-table';

export class PostServerDataSource extends ServerDataSource {

protected requestElements(): Observable {
let httpParams = this.createRequesParams();
return this.http.post(this.conf.endPoint, request_server, { observe: 'response' });
}

}
```

anotherComponent.ts

```
swiftListTable() {
const request_server = JSON.stringify({ "userType": this.currentUser.role, "authName": this.currentUser.username })
this.source = new PostServerDataSource(this.http,{endPoint: this.service.apiURL + 'swift/pagination', dataKey: 'content', pagerLimitKey:"_limit",
pagerPageKey:"_page",
sortDirKey: "pageable",
sortFieldKey: "pageable",
totalKey:'totalElements'});
}
```
}
```