Blazor应用程序输入选择不从数据库中提取

Question

我试图从数据库表中提取国家列表，但没有显示结果集，表中有数据。下面是我所做的。尽管如此，我还是第一次使用InputSelect字段，所以我还没有完全理解它。我能够使用这个与输入文本一起提取数据。所以看起来我的数据库连接字符串很好。

//Razor Page     
@inject ICountryData _db            
<h1>Choose a Country</h1>            
<h4>Countries</h4>
@if (Countries is null)
{
<p><em>Loading...</em></p>
}
else
{
<div class="col-6">
<EditForm Model="@DisplayCountry">
<div class="form-group">
<label class="col-2 font-weight-bold">CountryName:</label>
<InputSelect  @bind-Value="DisplayCountry.CountryName" class="form-control">
<option value="">Select</option>
@foreach (var person in Countries)
{
<option value="@DisplayCountry.CountryName">     @DisplayCountry.CountryCode </option>
}
</InputSelect>
</div>
<button type="submit" class="btn btn-primary">Submit</button>
</EditForm>
</div>
}
@code {
private List<CountryModel> Countries;
private DisplayCountryModel DisplayCountry = new DisplayCountryModel();
protected override async Task OnInitializedAsync()
{
Countries = await _db.GetCountry();
}
private async Task InsertCountry()
{
CountryModel C = new CountryModel
{
CountryCode = DisplayCountry.CountryCode,
CountryName = DisplayCountry.CountryName,
};
await _db.InsertCountry(C);
Countries.Add(C);
DisplayCountry = new DisplayCountryModel();
}
}       

using DataAccessLibrary.Models;
using System;
using System.Collections.Generic;
using System.Text;
using System.Threading.Tasks;
namespace DataAccessLibrary
{
public class CountryData : ICountryData
{
private readonly ISqlDataAccess _db;
public CountryData(ISqlDataAccess db)
{
_db = db;
}
public Task<List<CountryModel>> GetCountry()
{
string sql = "select * from dbo.Country";
return _db.LoadData<CountryModel, dynamic>(sql, new { });
}
public Task InsertCountry(CountryModel Country)
{
string sql = @"insert into dbo.Country (CountryCode, CountryName)
values (@CountryCode, @CountryName);";
return _db.SaveData(sql, Country);
}
}
}

Answer 1

@foreach变量错误。我把它改写成下面的样子，它起作用了。

<InputSelect @bind-Value="DisplayCountry.CountryName" class="form-control">
<option value="">Select</option>
@foreach (var item in Countries)
{
<option value="@item.CountryCode"> @item.CountryName </option>
}
</InputSelect>