c# - Controller 从 ASP.NET MVC5 表单接收空值

Question

我有两个来自市场及其分支机构的下拉菜单，所以我在选择市场时做到了，它将其分支机构加载到分支机构下拉菜单中

html设计

<div style="width : 50%">
        <div class="form-group" style="display:inline-block">
            @Html.LabelFor(m => m.Market)
            @Html.DropDownListFor(m => m.Market, new SelectList(Model.Markets, "Id", "Name"), "Select Market", new { @class = "form-control" })
        </div>
        <div class="form-group" style="float:right">
            @Html.LabelFor(m => m.Branch)
            @Html.DropDownListFor(m => m.Branch, new SelectList("", "Id", "Name"), "Select Branch", new { @class = "form-control" })
        </div>
    </div>

以及用于加载分支的 ajax

 $(function () {
    $("#Market").on("change", function () {
        $.get("/Home/GetBranches", { id: $("#Market").val() }, function (data) {
            $("#Branch").empty();
            console.log(data);
            $.each(data, function (index, row) {
                $("#Branch").append("<option value='" + row.Id + "'>" + row.Name + "</option>")
            });
        });
    });

一切正常，但是当我发布整个表格时

   @using (Html.BeginForm("Index", "Home", FormMethod.Post))
{

    <div style="width : 50%">
        <div class="form-group" style="display:inline-block">
            @Html.LabelFor(m => m.Market)
            @Html.DropDownListFor(m => m.Market, new SelectList(Model.Markets, "Id", "Name"), "Select Market", new { @class = "form-control" })
        </div>
        <div class="form-group" style="float:right">
            @Html.LabelFor(m => m.Branch)
            @Html.DropDownListFor(m => m.Branch, new SelectList("", "Id", "Name"), "Select Branch", new { @class = "form-control" })
        </div>
    </div>

    <input class='datepicker' />

    <div style="width: 50%">
        <div class="form-group" style="display:inline-block">
            @Html.LabelFor(m => m.Date)
            @Html.TextBoxFor((m => m.Date), new { @class = "form-control form-inline datepicker", placeholder = "eg 1 Jan 2018" })
            @Html.ValidationMessageFor(m => m.Date)
        </div>
        <div class="form-group" style="float:right">
            @Html.LabelFor(m => m.Time)
            @Html.TextBoxFor(m => m.Time, new { @class = "form-control form-inline", placeholder = "hh:mm" })
            @Html.ValidationMessageFor(m => m.Time)
        </div>
    </div>

    <div class="form-group">
        @Html.LabelFor(m => m.CustName)
        @Html.TextBoxFor(m => m.CustName, new { @class = "form-control fouc" })
        @Html.ValidationMessageFor(m => m.CustName)
    </div>
    <div class="form-group">
        @Html.LabelFor(m => m.OrderNumber)
        @Html.TextBoxFor(m => m.OrderNumber, new { @class = "form-control" })
        @Html.ValidationMessageFor(m => m.OrderNumber)
    </div>
    <div class="form-group">
        @Html.LabelFor(m => m.Total)
        @Html.EditorFor(m => m.Total, new { htmlAttributes = new { @class = "form-control" } })
        @Html.ValidationMessageFor(m => m.Total)
    </div>
    <div class="form-group">
        @Html.LabelFor(m => m.CouponValue)
        @Html.EditorFor(m => m.CouponValue, new { htmlAttributes = new { @class = "form-control" } })
        @Html.ValidationMessageFor(m => m.CouponValue)
    </div>
    <div class="form-group">
        @Html.LabelFor(m => m.Notes)
        @Html.TextBoxFor(m => m.Notes, new { @class = "form-control" })
        @Html.ValidationMessageFor(m => m.Notes)
    </div>
    <button type="submit" class="btn btn-primary btn-lg">Save</button>

我收到分支空值

当我在浏览器中打开网络时，我可以看到传递的值

模型类

    using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Linq;
using System.Web;
using Takers.Models;

namespace Takers.ViewModel
{
    public class OrderView
    {
        [Required]
        public string OrderNumber { get; set; }

        [Required]
        public string CustName { get; set; }

        [Required]
        public decimal CouponValue { get; set; }

        [Required]
        public string Notes { get; set; }

        [Required]
        public string UserName { get; set; }

        [Required]
        public decimal Total { get; set; }

        public string Time { get; set; }

        public string Date { get; set; }

        public Market Market { get; set; }

        public Branch Branch { get; set; }

        public ICollection<Market> Markets { get; set; }

        public ICollection<Branch> Branches { get; set; }

        public DateTime GetDateTime()
        {
            return DateTime.Parse($"{Date} {Time}");
        }
    }
}

在调试时我可以看到指向模型类的点并将分支设置为空值我很困惑谢谢你

Answer 1

Branch 是内置模型绑定(bind)器一无所知的类，您将不得不编写 custom model binder将 Branch 发布的值转换为 Branch 实例或将模型中的 Branch 转换为 string 或 int:

public string Branch { get;放; }