[英]Consuming Value from API
我是MVC的新手,并且正在尝试开发一个货币交换,该货币交换具有一个文本框和两个要交换货币的下拉列表。 我使用了具有表的API Web服务,该表包含货币名称,国家和值。 我的问题是,一旦用户在ConversionRate中插入金额后发布操作方法,就从API计算值,因为我总是得到0值! 我在这里做错了什么?
索引操作方法
[HttpPost]
public ActionResult Index(Currencies cur)
{
if (cur.ConversionRate.Equals(null))
{
ModelState.AddModelError("", "Please enter a numeric value");
}
if (cur.FromCurrencyId == cur.ToCurrencyId)
{
//do something if same currecnies and return.
ModelState.AddModelError("", "Can't make the conversion for the same curreny");
}
else
{
if (ModelState.IsValid)
{
CurrenciesClient Cur = new CurrenciesClient();
var listCurrency = Cur.findAll().ToList();
Currencies model = new Currencies();
model.FromCurrencies = new SelectList(listCurrency,"FromCurrencyId", "CurrencyName","Value");
model.ToCurrencies = new SelectList(listCurrency, "ToCurrencyId", "CurrencyName","Value" );
ViewBag.TheResult = listCurrency.Where(c => c.FromCurrencyId == cur.FromCurrencyId && c.ToCurrencyId == cur.ToCurrencyId).FirstOrDefault().ConversionRate * cur.Value;
return PartialView("_CurrencyValue");
}
}
return View();
}
API Web服务CurrenciesClient
public class CurrenciesClient
{
private string base_Url = "http://localhost:51646/api/";
public IEnumerable<Currencies> findAll()
{
try
{
HttpClient client = new HttpClient();
client.BaseAddress = new Uri(base_Url);
client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
HttpResponseMessage response = client.GetAsync("currencies").Result;
if (response.IsSuccessStatusCode)
{
var resposeData = response.Content.ReadAsStringAsync().Result;
var Currency = JsonConvert.DeserializeObject<List<Currencies>>(resposeData);
return Currency;
}
return null;
}
catch
{
return null;
}
}
}
货币VM
public class Currencies
{
public int Id { get; set; }
[Required(ErrorMessage = " message")]
public int FromCurrencyId { get; set; }
public SelectList FromCurrencies { get; set; }
[Required]
public int ToCurrencyId { get; set; }
public SelectList ToCurrencies { get; set; }
public string CurrencyName { get; set; }
public string CurrencyCountry { get; set; }
[Required(ErrorMessage ="Please enter a numeric value")]
public decimal ConversionRate { get; set; }
public decimal Value { get; set; }
public SelectList AvailableCurrencies { get; set; }
}
索引检视
@model Project.ViewModels.Currencies
@{
ViewBag.Title = "Index";
}
<div id="ConversionSection">
@using (Ajax.BeginForm(new AjaxOptions { HttpMethod = "post", InsertionMode = InsertionMode.Replace, UpdateTargetId = "ConversionSection" }))
{
@Html.AntiForgeryToken()
@Html.ValidationSummary(true, "", new { @class = "text-danger" })
@Html.TextBoxFor(m => m.ConversionRate, new { @class = "form-control" })
@Html.DropDownListFor(m => m.FromCurrencyId, Model.FromCurrencies as IEnumerable<SelectListItem>, new { @class = "form-control" })
@Html.DropDownListFor(m => m.ToCurrencyId, Model.ToCurrencies as IEnumerable<SelectListItem>, new { @class = "form-control" })
@Html.ValidationMessageFor(model => model.ToCurrencyId, "", new { @class = "text-danger" })
<br />
<button type="submit" class="btn btn-primary">Convert</button>
}
</div>
@section scripts{
<script src="~/Scripts/jquery.unobtrusive-ajax.min.js"></script>
}
您允许用户在表单中输入转化率,然后在API中进行查找。 这是不合逻辑的。 您不希望用户自己输入转化率-这是您为了计算交换而保留的数据。
您没有让用户输入的是他们想要兑换的货币量。 这保存在ViewModel的“值”字段中。 由于未输入该值,因此它始终默认为0,这就是为什么当您执行ConversionRate * cur.Value
它始终返回0。(该等式中的ConversionRate正确地是API返回的值,而不是输入的由用户)。
要解决,只需更改
@Html.TextBoxFor(m => m.ConversionRate, new { @class = "form-control" })
至
@Html.TextBoxFor(m => m.Value, new { @class = "form-control" })
您的UI可能还应该包含一个标签,告诉用户输入什么!
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