角度选择值字符串解析为整数

Question

我正在尝试从角度选择控件中获取选定值到 Asp.net Core 3.0 WebApi。 当我调试时发现，所选值是字符串格式，但我的数据模型接受整数。 我收到以下错误

无法将 JSON 值转换为 System.Int32。 路径：$.bankID | 行号：0 | BytePositionInLine：77。

有没有一种简单的方法可以将字符串值从选择控件转换为整数。

角度代码

组件.ts

export class BankAccountComponent implements OnInit {
  constructor(private fb: FormBuilder, private bankService: BankService,
              private service: BankAccountService) { }
  bankAccountForms: FormArray = this.fb.array([]);
  bankList = [];
  ngOnInit() {
    this.bankService.getBankList()
    .subscribe( res => this.bankList = res as []);
    this.addBankAccountForm();

    this.service.getBankAccountList().subscribe(
      res => {
        if (res == []) {
          this.addBankAccountForm();
        }
        else {
          // generate formarray as per the data received from BankAccont table
          (res as []).forEach((bankAccount: any) => {
            this.bankAccountForms.push(this.fb.group({
              bankAccountID: [bankAccount.bankAccountID],
              accountNumber: [bankAccount.accountNumber, Validators.required],
              accountHolder: [bankAccount.accountHolder, Validators.required],
              bankID: [bankAccount.bankID, Validators.min(1)],
              IFSC: [bankAccount.ifsc, Validators.required]
            }));
          });
        }
      }
    );

  }
  addBankAccountForm(){
    this.bankAccountForms.push(this.fb.group({
      bankAccountID: [0],
      accountNumber: ['', Validators.required],
      accountHolder: ['', Validators.required],
      bankID: [0, Validators.min(1)], // here we are using drop down
      IFSC: ['', Validators.required],

    }));
  }

  recordSubmit(fg: FormGroup) {
    (fg.value.bankAccountID == 0)
      this.service.postBankAccount(fg.value).subscribe(
        (res: any) => {
          fg.patchValue({ bankAccountID: res.bankAccountID });
          //this.showNotification('insert');
        });
  }
}

组件.html

<form  class="tr" [formGroup] ="fg"
    *ngFor="let fg  of bankAccountForms.controls" (submit)="recordSubmit(fg)">
<div class="td">
    <input  class="form-control" formControlName="accountNumber">
</div>
<div class="td">
    <input  class="form-control" formControlName="accountHolder">
</div>
<div class="td">
    <select  class="form-control" formControlName="bankID">
        <option value="0">Select</option>

        <option *ngFor="let item of bankList" value="{{item.bankID}}">{{item.bankName}}</option>

    </select>
</div>
<div class="td">
    <input  class="form-control" formControlName="IFSC">
</div>
<div class="td">
    <button class="btn btn-success" [disabled]="fg.invalid">
        <i class="far fa-save fa-lg"></i> 
        Submit</button>
</div>
</form>

服务.ts

 postBankAccount(formData) {
    return this.http.post(environment.apiBaseURI + '/BankAccount', formData);
}

Component.ts WebApi代码
WebAPI/模型

public class BankAccount
{
    [Key]
    public int BankAccountID { get; set; }

    [MaxLength(20)]
    [Required]
    public string AccountNumber { get; set; }

    [MaxLength(100)]
    [Required]
    public string AccountHolder { get; set; }

    [Required]
    public int BankID { get; set; }

    [MaxLength(20)]
    [Required]
    public string IFSC { get; set; }
}

WebAPI 控制器

[HttpPost]
    public async Task<ActionResult<BankAccount>> PostBankAccount(BankAccount bankAccount)
    {

        _context.BankAccounts.Add(bankAccount);
        await _context.SaveChangesAsync();

        return CreatedAtAction("GetBankAccount", new { id = bankAccount.BankAccountID }, bankAccount);
    }

Answer 1

在将数据发送到您的 API 之前，只需在它们前面添加'+' ，即可将所有数值从string to number 。

Answer 2

如果我正确理解你想要做什么，我有 2 个解决方案

1. 当您将数据发送到服务器时，将值更改为数字

recordSubmit(fg: FormGroup) {
   if (fg.value.bankAccountID == 0) {
      fg.value.bankID = +fg.value.bankID;   // the + operator will change the type to number
      this.service.postBankAccount(fg.value).subscribe(
        (res: any) => {
          fg.patchValue({ bankAccountID: res.bankAccountID });
          //this.showNotification('insert');
        });
   }
}

2. change the value to number when the select value will be changed in html

    <select #bankIdSelect class="form-control" (change)="onChangeBankId(bankIdSelect.value)">
        <option value="0">Select</option>

        <option *ngFor="let item of bankList" value="{{item.bankID}}">{{item.bankName}}</option>

    </select>

在 ts

onChangeBankId(bankId) {
    this.fg.get('bankID').patchValue(+bankId);
}