C# 如何在MVC Net Core中编辑可枚举或列表视图

如何为列表创建编辑视图

以下是单个项目的示例视图和模型，可以正常工作。 下一个问题是，我有一个要编辑的项目列表。我该怎么做

型号：

public partial class ProductViewModel
{
    public int ProductId { get; set; }
    public string ProductName { get; set; }
    public string ProductDescription { get; set; }
    public string ImageLocation { get; set; }
}

@model ProductViewModel

@{
    ViewData["Title"] = "Edit";
}

<h2>Edit</h2>

<h4>Product</h4>
<hr />
<div class="row">
    <div class="col-md-4">
        <form asp-action="Edit">
            <div asp-validation-summary="ModelOnly" class="text-danger"></div>
            <input type="hidden" asp-for="ProductId" />
            <div class="form-group">
                <label asp-for="ProductName" class="control-label"></label>
                <input asp-for="ProductName" class="form-control" />
                <span asp-validation-for="ProductName" class="text-danger"></span>
            </div>
            <div class="form-group">
                <label asp-for="ProductDescription" class="control-label"></label>
                <input asp-for="ProductDescription" class="form-control" />
                <span asp-validation-for="ProductDescription" class="text-danger"></span>
            </div>
            <div class="form-group">
                <input type="submit" value="Save" class="btn btn-default" />
            </div>
        </form>
    </div>
</div>

using System.Collections.Generic;   

public class ShoppingCart : List<CartLine>
{
    public ShoppingCart() { }
    public ShoppingCart(IEnumerable<CartLine> collection) : base(collection) { }
    public ShoppingCart(int capacity) : base(capacity) { }
}    

public class ShoppingCartViewModel
{
    public ShoppingCart ShoppingCart { get; set; }
    public string ReturnUrl { get; set; }
}

public class CartLine
{
    public int CartLineId { get; set; }
    public Product Product { get; set; }
    public int Quantity { get; set; }
}

@model ShoppingCartViewModel
@{
    ViewData["Title"] = "Index";
}

<h2>Edit Shopping Cart</h2>

<h4>edit</h4>
<hr />
<div class="row">
    <div class="col-md-4">
        @foreach (var item in Model.ShoppingCart)
        {
            <form asp-action="Edit">
                <div asp-validation-summary="ModelOnly" class="text-danger"></div>
                <input type="hidden" asp-for="modelItem=>item.CartLineId" />
                <div class="form-group">
                    <label asp-for="modelItem=>item.Product.ProductName" class="control-label"></label>
                    <input asp-for="modelItem=>item.Product.ProductName" class="form-control" />
                    <span asp-validation-for="modelItem=>item.Product.ProductName" class="text-danger"></span>
                </div>

成功查看：

public partial class ProductViewModel
{
    public int ProductId { get; set; }
    public string ProductName { get; set; }
    public string ProductDescription { get; set; }
    public string ImageLocation { get; set; }
}

@model ProductViewModel

@{
    ViewData["Title"] = "Edit";
}

<h2>Edit</h2>

<h4>Product</h4>
<hr />
<div class="row">
    <div class="col-md-4">
        <form asp-action="Edit">
            <div asp-validation-summary="ModelOnly" class="text-danger"></div>
            <input type="hidden" asp-for="ProductId" />
            <div class="form-group">
                <label asp-for="ProductName" class="control-label"></label>
                <input asp-for="ProductName" class="form-control" />
                <span asp-validation-for="ProductName" class="text-danger"></span>
            </div>
            <div class="form-group">
                <label asp-for="ProductDescription" class="control-label"></label>
                <input asp-for="ProductDescription" class="form-control" />
                <span asp-validation-for="ProductDescription" class="text-danger"></span>
            </div>
            <div class="form-group">
                <input type="submit" value="Save" class="btn btn-default" />
            </div>
        </form>
    </div>
</div>

using System.Collections.Generic;   

public class ShoppingCart : List<CartLine>
{
    public ShoppingCart() { }
    public ShoppingCart(IEnumerable<CartLine> collection) : base(collection) { }
    public ShoppingCart(int capacity) : base(capacity) { }
}    

public class ShoppingCartViewModel
{
    public ShoppingCart ShoppingCart { get; set; }
    public string ReturnUrl { get; set; }
}

public class CartLine
{
    public int CartLineId { get; set; }
    public Product Product { get; set; }
    public int Quantity { get; set; }
}

@model ShoppingCartViewModel
@{
    ViewData["Title"] = "Index";
}

<h2>Edit Shopping Cart</h2>

<h4>edit</h4>
<hr />
<div class="row">
    <div class="col-md-4">
        @foreach (var item in Model.ShoppingCart)
        {
            <form asp-action="Edit">
                <div asp-validation-summary="ModelOnly" class="text-danger"></div>
                <input type="hidden" asp-for="modelItem=>item.CartLineId" />
                <div class="form-group">
                    <label asp-for="modelItem=>item.Product.ProductName" class="control-label"></label>
                    <input asp-for="modelItem=>item.Product.ProductName" class="form-control" />
                    <span asp-validation-for="modelItem=>item.Product.ProductName" class="text-danger"></span>
                </div>

@model产品视图模型
@{
ViewData[“标题”]=“编辑”；
}
编辑
产品

现在，我有了一个带有项目列表的模型，如何在视图中访问它们？我想编辑我的购物车中的所有项目，更具体地说是数量。正在尝试正确调用委托linq查询

错误：

当前上下文中不存在名称“modelItem”

型号：

public partial class ProductViewModel
{
    public int ProductId { get; set; }
    public string ProductName { get; set; }
    public string ProductDescription { get; set; }
    public string ImageLocation { get; set; }
}

@model ProductViewModel

@{
    ViewData["Title"] = "Edit";
}

<h2>Edit</h2>

<h4>Product</h4>
<hr />
<div class="row">
    <div class="col-md-4">
        <form asp-action="Edit">
            <div asp-validation-summary="ModelOnly" class="text-danger"></div>
            <input type="hidden" asp-for="ProductId" />
            <div class="form-group">
                <label asp-for="ProductName" class="control-label"></label>
                <input asp-for="ProductName" class="form-control" />
                <span asp-validation-for="ProductName" class="text-danger"></span>
            </div>
            <div class="form-group">
                <label asp-for="ProductDescription" class="control-label"></label>
                <input asp-for="ProductDescription" class="form-control" />
                <span asp-validation-for="ProductDescription" class="text-danger"></span>
            </div>
            <div class="form-group">
                <input type="submit" value="Save" class="btn btn-default" />
            </div>
        </form>
    </div>
</div>

using System.Collections.Generic;   

public class ShoppingCart : List<CartLine>
{
    public ShoppingCart() { }
    public ShoppingCart(IEnumerable<CartLine> collection) : base(collection) { }
    public ShoppingCart(int capacity) : base(capacity) { }
}    

public class ShoppingCartViewModel
{
    public ShoppingCart ShoppingCart { get; set; }
    public string ReturnUrl { get; set; }
}

public class CartLine
{
    public int CartLineId { get; set; }
    public Product Product { get; set; }
    public int Quantity { get; set; }
}

@model ShoppingCartViewModel
@{
    ViewData["Title"] = "Index";
}

<h2>Edit Shopping Cart</h2>

<h4>edit</h4>
<hr />
<div class="row">
    <div class="col-md-4">
        @foreach (var item in Model.ShoppingCart)
        {
            <form asp-action="Edit">
                <div asp-validation-summary="ModelOnly" class="text-danger"></div>
                <input type="hidden" asp-for="modelItem=>item.CartLineId" />
                <div class="form-group">
                    <label asp-for="modelItem=>item.Product.ProductName" class="control-label"></label>
                    <input asp-for="modelItem=>item.Product.ProductName" class="form-control" />
                    <span asp-validation-for="modelItem=>item.Product.ProductName" class="text-danger"></span>
                </div>

使用System.Collections.Generic；
公共类ShoppingCart:列表
{
公共购物车（）{}
公共购物车（IEnumerable集合）：基本（集合）{}
公共购物车（整数容量）：基本（容量）{}
}    
公共类ShoppingCartViewModel
{
公共购物车购物车{get；set；}
公共字符串ReturnUrl{get；set；}
}
公共类CartLine
{
公共int CartLineId{get；set；}
公共产品产品{get；set；}
公共整数数量{get；set；}
}

视图不工作，输入类型出现以下错误，并进一步说明：

public partial class ProductViewModel
{
    public int ProductId { get; set; }
    public string ProductName { get; set; }
    public string ProductDescription { get; set; }
    public string ImageLocation { get; set; }
}

@model ProductViewModel

@{
    ViewData["Title"] = "Edit";
}

<h2>Edit</h2>

<h4>Product</h4>
<hr />
<div class="row">
    <div class="col-md-4">
        <form asp-action="Edit">
            <div asp-validation-summary="ModelOnly" class="text-danger"></div>
            <input type="hidden" asp-for="ProductId" />
            <div class="form-group">
                <label asp-for="ProductName" class="control-label"></label>
                <input asp-for="ProductName" class="form-control" />
                <span asp-validation-for="ProductName" class="text-danger"></span>
            </div>
            <div class="form-group">
                <label asp-for="ProductDescription" class="control-label"></label>
                <input asp-for="ProductDescription" class="form-control" />
                <span asp-validation-for="ProductDescription" class="text-danger"></span>
            </div>
            <div class="form-group">
                <input type="submit" value="Save" class="btn btn-default" />
            </div>
        </form>
    </div>
</div>

using System.Collections.Generic;   

public class ShoppingCart : List<CartLine>
{
    public ShoppingCart() { }
    public ShoppingCart(IEnumerable<CartLine> collection) : base(collection) { }
    public ShoppingCart(int capacity) : base(capacity) { }
}    

public class ShoppingCartViewModel
{
    public ShoppingCart ShoppingCart { get; set; }
    public string ReturnUrl { get; set; }
}

public class CartLine
{
    public int CartLineId { get; set; }
    public Product Product { get; set; }
    public int Quantity { get; set; }
}

@model ShoppingCartViewModel
@{
    ViewData["Title"] = "Index";
}

<h2>Edit Shopping Cart</h2>

<h4>edit</h4>
<hr />
<div class="row">
    <div class="col-md-4">
        @foreach (var item in Model.ShoppingCart)
        {
            <form asp-action="Edit">
                <div asp-validation-summary="ModelOnly" class="text-danger"></div>
                <input type="hidden" asp-for="modelItem=>item.CartLineId" />
                <div class="form-group">
                    <label asp-for="modelItem=>item.Product.ProductName" class="control-label"></label>
                    <input asp-for="modelItem=>item.Product.ProductName" class="form-control" />
                    <span asp-validation-for="modelItem=>item.Product.ProductName" class="text-danger"></span>
                </div>

@model ShoppingCartViewModel
@{
ViewData[“标题”]=“索引”；
}
编辑购物车
编辑

@foreach（Model.ShoppingCart中的var项）
{

您不需要在asp标记帮助程序中使用模型表达式。您可以使用

@

符号直接在foreach循环中访问项目

因此，它将取代

asp for=“modelItem=>item.Product.ProductName”

而成为

asp for=“@item.Product.ProductName”

@foreach（Model.ShoppingCart中的var项）
{
}

有关更多信息，请查看