从阵列无法正常工作

Question

盖伊，我在这里做错了什么？ 我试图根据另一个对象中属性的值从一个数组中获取一个项目。 我试过使用.find和.filter，但得到了错误的结果。 要么它返回数组中的第一个项目作为结果，要么返回声明对象，沿着该行的某个位置丢失了要从数组中提取的对象。

  getContractTypes() {
this.recruitmentauthorisationservice.getContractTypes().subscribe(data => {
  this.contractTypesList = data;
  console.log(this.contractTypesList); // All object return succesfully

  let rTypeId = this.selectedRequest['rapRequestTypeId']; 
  console.log('rTypeId: ' + rTypeId); // Correct value of type number returned

  this.selectedRequestType = this.contractTypesList.filter(x => x.RAPRequestTypeId === this.selectedRequest.RAPRequestTypeId)[0];
  console.log(this.selectedRequestType); //Return's wrong object. i.e first item in the array

  //Tried a different way, this return's the empty declaration object when you console.log.
  // for (var i = 0; i < this.contractTypesList.length; i++) {
  //   console.log(this.contractTypesList[i]);
  //   if(this.contractTypesList[i].RAPRequestTypeId === this.selectedRequest['rapRequestTypeId']){
  //     this.selectedRequestType = this.contractTypesList[i];
  //   }
  // }
});

}

this.getContractTypes(); is being called in ngOnInit(){}

result object is initialiased like this:
  selectedRequestType: ContractType = {
    RAPRequestTypeId: 0,
    RAPRequestTypeTitle: ''
  };

and the object model is defines like this:
    export interface ContractType{
    RAPRequestTypeId?: number;
    RAPRequestTypeTitle?: string
}