在联系人创建中，我想从下拉列表中分配客户或供应商

Question

我有两个问题。

1.问题： 当我将我的 selection 添加到剃刀页面时，模型中的所有必填字段验证不再起作用。

没有 selection 的模型验证

添加 selection 时未验证

当下拉菜单位于 Razor 中时 html 验证无效，它会因 NULL 值而崩溃，我想防止这种情况发生。就像没有 select 选项一样。这是为什么？

2。问题： 当我 select 我的下拉列表中的一位客户 (CustomerDropDown.CusId) 我想将 ID 填写到我的 ID 联系人字段中（ contacts.CustomerId)。如何从下拉菜单中获取 selected 值并将其 post 发送给我的联系人 contacts.CustomerId？

== c#代码==

using System;
using System.Collections.Generic;
using System.Diagnostics.CodeAnalysis;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.RazorPages;
using Microsoft.EntityFrameworkCore;
using Microsoft.AspNetCore.Mvc.Rendering;
using WorkCollaboration.Data;
using WorkCollaboration.Models;

namespace WorkCollaboration.Pages.Contacts
{ 
    public class CreateModel : PageModel
    {
        private readonly WorkCollaboration.Data.WorkCollaborationContext _context;

        public CreateModel(WorkCollaboration.Data.WorkCollaborationContext context)
        {
            _context = context;
        }

    public async Task<IActionResult> OnGetAsync()
        {
            CustomerDropDownDisp = await _context.CustomerDropDown.ToListAsync();  // Added for DropDown
            SupplierDropDownDisp = await _context.SupplierDropDown.ToListAsync();  // Added for DropDown
            return Page();
        }

        [BindProperty]
        public Contact Contact { get; set; }
        public IEnumerable<CustomerDropDown> CustomerDropDownDisp { get; set; }
        public IEnumerable<SupplierDropDown> SupplierDropDownDisp { get; set; }

        // To protect from overposting attacks, enable the specific properties you want to bind to, for
        // more details, see https://aka.ms/RazorPagesCRUD.
        public async Task<IActionResult> OnPostAsync()
        {
            if (!ModelState.IsValid)
            {
                return Page();
            }
            _context.Contact.Add(Contact);
            await _context.SaveChangesAsync();

            return RedirectToPage("/ContactsOverview/Index");
        }
    }
}

== Razor 页面代码 ==

@page 
@using WorkCollaboration.Models
@model WorkCollaboration.Pages.Contacts.CreateModel

@{
    ViewData["Title"] = "Create";
    ViewData["RandomId"] = Guid.NewGuid().GetHashCode();
}

<h1>Create</h1>
<h4>Contact</h4>
<p>
    <a asp-page="/ContactsOverview/Index">Back to Index</a>
</p>
<hr />
<div class="row">
    <div class="col-md-4">
        <form method="post">
            <div asp-validation-summary="ModelOnly" class="text-danger"></div>
            <div class="form-group">
                <label asp-for="Contact.ContactId" class="control-label"></label>
                <input asp-for="Contact.ContactId" value='@ViewData["RandomId"]' readonly="readonly" class="form-control" />
                <span asp-validation-for="Contact.ContactId" class="text-danger"></span>
            </div>
            <div class="form-group">
                <label asp-for="Contact.LastName" class="control-label"></label>
                <input asp-for="Contact.LastName" class="form-control" />
                <span asp-validation-for="Contact.LastName" class="text-danger"></span>
            </div>
            <div class="form-group">
                <label asp-for="Contact.FirstName" class="control-label"></label>
                <input asp-for="Contact.FirstName" class="form-control" />
                <span asp-validation-for="Contact.FirstName" class="text-danger"></span>
            </div>
            <div class="form-group">
                <label asp-for="Contact.CustomerId" class="control-label"></label>
            </div>
            <select id="CusId" asp-for="CustomerDropDownDisp" asp-items="@(new SelectList(Model.CustomerDropDownDisp,"CusId","CusName"))">
                <option value="">--Choose Customer--</option>
                <option value="1" selected>None</option>>
            </select>
            <div class="form-group">
                <input asp-for="Contact.CustomerId" class="form-control" />
                <span asp-validation-for="Contact.CustomerId" class="text-danger"></span>
            </div>
            <div class="form-group">
                <label asp-for="Contact.SupplierId" class="control-label"></label>
            </div>
            <select id="SupId" asp-for="SupplierDropDownDisp" asp-items="@(new SelectList(Model.SupplierDropDownDisp,"SupId","SupName"))">
                <option value="">--Choose Supplier--</option>
                <option value="1" selected>None</option>>
            </select>
            <div class="form-group">
                <input asp-for="Contact.SupplierId" class="form-control" />
                <span asp-validation-for="Contact.SupplierId" class="text-danger"></span>
            </div>
            <div class="form-group">
                <label asp-for="Contact.PrivateStreet" class="control-label"></label>
                <input asp-for="Contact.PrivateStreet" class="form-control" />
                <span asp-validation-for="Contact.PrivateStreet" class="text-danger"></span>
            </div>
            <div class="form-group">
                <label asp-for="Contact.PrivateStreetNo" class="control-label"></label>
                <input asp-for="Contact.PrivateStreetNo" class="form-control" />
                <span asp-validation-for="Contact.PrivateStreetNo" class="text-danger"></span>
            </div>
            <div class="form-group">
                <label asp-for="Contact.PrivateStreetAdditionalInfo" class="control-label"></label>
                <input asp-for="Contact.PrivateStreetAdditionalInfo" class="form-control" />
                <span asp-validation-for="Contact.PrivateStreetAdditionalInfo" class="text-danger"></span>
            </div>
            <div class="form-group">
                <label asp-for="Contact.PrivateZip" class="control-label"></label>
                <input asp-for="Contact.PrivateZip" class="form-control" />
                <span asp-validation-for="Contact.PrivateZip" class="text-danger"></span>
            </div>
            <div class="form-group">
                <label asp-for="Contact.PrivateTown" class="control-label"></label>
                <input asp-for="Contact.PrivateTown" class="form-control" />
                <span asp-validation-for="Contact.PrivateTown" class="text-danger"></span>
            </div>
            <div class="form-group">
                @Html.LabelFor(model => model.Contact.PrivateCountry, htmlAttributes: new { @class = "form-group" })
                <div class="form-group">
                    @Html.DropDownListFor(model => model.Contact.PrivateCountry, new List<SelectListItem>
                    {
                        new SelectListItem {Text = "CH", Value = "CH", Selected = true },
                        new SelectListItem {Text = "D", Value = "D" },
                        new SelectListItem {Text = "FL", Value = "FL" },
                    }, new { @class = "form-control" })
                    @Html.ValidationMessageFor(model => model.Contact.PrivateCountry, "", new { @class = "text-danger" })
                </div>
            </div>
            <div class="form-group">
                <label asp-for="Contact.PrivatePhone" class="control-label"></label>
                <input asp-for="Contact.PrivatePhone" class="form-control" />
                <span asp-validation-for="Contact.PrivatePhone" class="text-danger"></span>
            </div>
            <div class="form-group">
                <label asp-for="Contact.BusinessPhone" class="control-label"></label>
                <input asp-for="Contact.BusinessPhone" class="form-control" />
                <span asp-validation-for="Contact.BusinessPhone" class="text-danger"></span>
            </div>
            <div class="form-group">
                <label asp-for="Contact.MobilePhone" class="control-label"></label>
                <input asp-for="Contact.MobilePhone" class="form-control" />
                <span asp-validation-for="Contact.MobilePhone" class="text-danger"></span>
            </div>
            <div class="form-group">
                <label asp-for="Contact.Mail" class="control-label"></label>
                <input asp-for="Contact.Mail" class="form-control" />
                <span asp-validation-for="Contact.Mail" class="text-danger"></span>
            </div>
            <div class="form-group">
                <input type="submit" value="Create" class="btn btn-primary" />
                <a href="/ContactsOverview/Index" class="btn btn-primary">Back to List</a>
            </div>
        </form>
    </div>
</div>

感谢您就如何获取 selected 值（下拉）到相应的联系人 ID 字段提供的帮助。

Answer 1

这是一个演示：

<div class="row">
    <div class="col-md-4">
        <form method="post">
            <div asp-validation-summary="ModelOnly" class="text-danger"></div>
            <div class="form-group">
                <label asp-for="Contact.ContactId" class="control-label"></label>
                <input asp-for="Contact.ContactId" value='@ViewData["RandomId"]' readonly="readonly" class="form-control" />
                <span asp-validation-for="Contact.ContactId" class="text-danger"></span>
            </div>
            <div class="form-group">
                <label asp-for="Contact.LastName" class="control-label"></label>
                <input asp-for="Contact.LastName" class="form-control" />
                <span asp-validation-for="Contact.LastName" class="text-danger"></span>
            </div>
            <div class="form-group">
                <label asp-for="Contact.FirstName" class="control-label"></label>
                <input asp-for="Contact.FirstName" class="form-control" />
                <span asp-validation-for="Contact.FirstName" class="text-danger"></span>
            </div>
            <div class="form-group">
                <label asp-for="Contact.CustomerId" class="control-label"></label>
            </div>
            <select id="CusId" asp-for="CustomerDropDownDisp" asp-items="@(new SelectList(Model.CustomerDropDownDisp,"CusId","CusName"))">
                <option value="">--Choose Customer--</option>
                <option value="1" selected>None</option>>
            </select>
            <div class="form-group">
                <input asp-for="Contact.CustomerId" class="form-control" />
                <span asp-validation-for="Contact.CustomerId" class="text-danger"></span>
            </div>
            <div class="form-group">
                <label asp-for="Contact.SupplierId" class="control-label"></label>
            </div>
            <select id="SupId" asp-for="SupplierDropDownDisp" asp-items="@(new SelectList(Model.SupplierDropDownDisp,"SupId","SupName"))">
                <option value="">--Choose Supplier--</option>
                <option value="1" selected>None</option>>
            </select>
            <div class="form-group">
                <input asp-for="Contact.SupplierId" class="form-control" />
                <span asp-validation-for="Contact.SupplierId" class="text-danger"></span>
            </div>
            <div class="form-group">
                <label asp-for="Contact.PrivateStreet" class="control-label"></label>
                <input asp-for="Contact.PrivateStreet" class="form-control" />
                <span asp-validation-for="Contact.PrivateStreet" class="text-danger"></span>
            </div>
            <div class="form-group">
                <label asp-for="Contact.PrivateStreetNo" class="control-label"></label>
                <input asp-for="Contact.PrivateStreetNo" class="form-control" />
                <span asp-validation-for="Contact.PrivateStreetNo" class="text-danger"></span>
            </div>
            <div class="form-group">
                <label asp-for="Contact.PrivateStreetAdditionalInfo" class="control-label"></label>
                <input asp-for="Contact.PrivateStreetAdditionalInfo" class="form-control" />
                <span asp-validation-for="Contact.PrivateStreetAdditionalInfo" class="text-danger"></span>
            </div>
            <div class="form-group">
                <label asp-for="Contact.PrivateZip" class="control-label"></label>
                <input asp-for="Contact.PrivateZip" class="form-control" />
                <span asp-validation-for="Contact.PrivateZip" class="text-danger"></span>
            </div>
            <div class="form-group">
                <label asp-for="Contact.PrivateTown" class="control-label"></label>
                <input asp-for="Contact.PrivateTown" class="form-control" />
                <span asp-validation-for="Contact.PrivateTown" class="text-danger"></span>
            </div>
            <div class="form-group">
                @Html.LabelFor(model => model.Contact.PrivateCountry, htmlAttributes: new { @class = "form-group" })
                <div class="form-group">
                    @Html.DropDownListFor(model => model.Contact.PrivateCountry, new List<SelectListItem>
                    {
                        new SelectListItem {Text = "CH", Value = "CH", Selected = true },
                        new SelectListItem {Text = "D", Value = "D" },
                        new SelectListItem {Text = "FL", Value = "FL" },
                    }, new { @class = "form-control" })
                    @Html.ValidationMessageFor(model => model.Contact.PrivateCountry, "", new { @class = "text-danger" })
                </div>
            </div>
            <div class="form-group">
                <label asp-for="Contact.PrivatePhone" class="control-label"></label>
                <input asp-for="Contact.PrivatePhone" class="form-control" />
                <span asp-validation-for="Contact.PrivatePhone" class="text-danger"></span>
            </div>
            <div class="form-group">
                <label asp-for="Contact.BusinessPhone" class="control-label"></label>
                <input asp-for="Contact.BusinessPhone" class="form-control" />
                <span asp-validation-for="Contact.BusinessPhone" class="text-danger"></span>
            </div>
            <div class="form-group">
                <label asp-for="Contact.MobilePhone" class="control-label"></label>
                <input asp-for="Contact.MobilePhone" class="form-control" />
                <span asp-validation-for="Contact.MobilePhone" class="text-danger"></span>
            </div>
            <div class="form-group">
                <label asp-for="Contact.Mail" class="control-label"></label>
                <input asp-for="Contact.Mail" class="form-control" />
                <span asp-validation-for="Contact.Mail" class="text-danger"></span>
            </div>
            <div class="form-group">
                <input type="submit" value="Create" class="btn btn-primary" />
                <a href="/ContactsOverview/Index" class="btn btn-primary">Back to List</a>
            </div>
        </form>
    </div>
</div>
<script src="~/lib/jquery/dist/jquery.min.js"></script>
<script src="~/lib/jquery-validation/dist/jquery.validate.min.js"></script>
<script src="~/lib/jquery-validation-unobtrusive/jquery.validate.unobtrusive.min.js"></script>
<script>
    $("#CusId").on("change", function () {
        $("#Contact_CustomerId").val($("#SupId").val());
    });
    $("#SupId").on("change", function () {
        $("#Contact_SupplierId").val($("#SupId").val());
    });
</script>

结果：

在联系人创建中，我想从下拉列表中分配客户或供应商

In the contact creation I want to assign a customer or supplier from a dropdown

validation

selectedvalue

razor

dropdown

asp.net-core