Type ‘Observable<() => any>’ is not assignable to type ‘Observable<Contract[]>’.

这是为什么啊

这是代码
getContracts(): Observable<Contract[]> {
return this.http.get(’/api/contracts’).map(response => response.json);
}
getContract(id: number): Observable {
// return this.http.get(’/api/contract’ + id).map(response => response.json);
return this.http.get(’/api/contract’ + id).map(response => response.json);
}
我稍微有点改动Stock 改成了 Contract