c# - 对于 MVC Model Binder，表单 POST 是否太大

Question

这个问题出现在.net core 3.1 MVC网站。

我无法让我的 POST 绑定(bind)到我的 Controller 操作(参数始终为空)。数据是从数据库加载的，是一个大的递归结构。 如果我在数据库中删除几百行 JSON(大约 2500 行)，它会绑定(bind) OK。

GET 显示完美。

即使我将我的 Action 方法参数从我的 ViewModel 更改为 IFormCollection，它仍然以 null 形式出现。这里有一些我不知道的限制吗？ 如果大小是问题，是否有更好的方法来发布数据？

父 View

<form id="frmAdditionalCodes" name="frmAdditionalCodes" method="post">
    <table class="table">
        <thead>
            <tr>
                <th>
                    @Html.DisplayNameFor(model => model.Code)
                </th>
                <th>
                    @Html.DisplayNameFor(model => model.FullName)
                </th>
                <th>
                    @Html.DisplayNameFor(model => model.Description)
                </th>
                <th></th>
            </tr>
        </thead>
        <tbody>

            <tr>

                <td style="width:50px">
                    @Html.DisplayFor(modelItem => Model.Code)
                    <input asp-for="@Model.Code" class="form-control" style="display:none" />
                </td>
                <td style="width:50px">
                    @Html.DisplayFor(modelItem => Model.FullName)
                    <input asp-for="@Model.FullName" class="form-control" style="display:none" />
                </td>
                <td style="width:50px">
                    @Html.DisplayFor(modelItem => Model.Description)
                    <input asp-for="@Model.Description" class="form-control" style="display:none" />
                </td>
                <td style="width:20px">
                    <span>
                        <i id="addTagItem" class="fas fa-folder-plus" title="Add child item"></i>
                    </span>

                </td>
                <td>
                    <partial name="~/Views/PartialViews/_SectionsAndTags.cshtml" model="@Model.Entities" view-data="ViewData" />
                </td>
                <td>
                </td>

            </tr>

        </tbody>
    </table>
</form>

subview

<table class="partial_table">
    <thead>
        <tr>

            <th>
                @Html.DisplayNameFor(model => model.Code)
            </th>
            <th>
                @Html.DisplayNameFor(model => model.FullName)
            </th>
            <th>
                @Html.DisplayNameFor(model => model.Description)
            </th>
            <th colspan="2">
                @Html.DisplayNameFor(model => model.Entities)
            </th>
        </tr>
    </thead>
    <tbody>
        @{ List<CdsDeclarationSectionAndTagItemViewModel> list = Model.ToList();
            for (int i = 0; i < list.Count(); i++)
            {
                    <tr>
                        @{
                            string elementNameCode = $"{list[i].Prefix}Code";
                            string elementNameFullName = $"{list[i].Prefix}FullName";
                            string elementNameDescription = $"{list[i].Prefix}Description";
                            string elementNameIsDeleted = $"{list[i].Prefix}IsDeleted";
                        }
                        <td>
                            <span>@list[i].Code</span>
                            <input asp-for="@list[i].Code" name="@elementNameCode" class="form-control" style="display: none" />
                        </td>
                        <td>
                            <span>@list[i].FullName</span>
                            <input asp-for="@list[i].FullName" class="form-control" name="@elementNameFullName" style="display: none" />
                        </td>
                        <td>
                            <span>@list[i].Description</span>
                            <input asp-for="@list[i].Description" class="form-control" name="@elementNameDescription" style="display: none" />
                        </td>
                        <td>
                            @if (list[i].Entities?.Length > 0)
                            {<img id="collapseItem" state="expanded" width="20" height="20" src="~/images/minus_PNG24.png" />
                            }

                            <span>
                                <i id="editTagItem" class="fas fa-pencil-alt" title="Edit item"></i>
                                <i id="deleteTagItem" class="far fa-trash-alt" title="Delete item"></i>
                                <i id="addTagItem" class="fas fa-folder-plus" title="Add child item"></i>
                                <i id="updateTagItem" class="far fa-save" title="Save changes" style="display: none"></i>
                                <i id="cancelTagItem" class="fas fa-undo-alt" title="Undo changes" style="display: none"></i>
                            </span>

                        </td>
                        <td>
                            @if (list[i].Entities?.Length > 0)
                            {
                                <partial name="~/Views/PartialViews/_SectionsAndTags.cshtml" model="@list[i].Entities" />
                            }
                        </td>
                        <td>
                            <input type="hidden" value="false" name="@elementNameIsDeleted" />

                        </td>

                    </tr>
            }
        }
    </tbody>
</table>

View 模型

public class CdsDeclarationSectionAndTagViewModel
{
    public string Code { get; set; }

    public string FullName { get; set; }

    public string Description { get; set; }

    public CdsDeclarationSectionAndTagItemViewModel[] Entities { get; set; }
}

public class CdsDeclarationSectionAndTagItemViewModel
{
    public string Code { get; set; }
    public string FullName { get; set; }
    public string Description { get; set; }

    public CdsDeclarationSectionAndTagItemViewModel[] Entities { get; set; }

    public string Prefix { get; set; }

    public bool IsDeleted { get; set; }
}

Controller 这里 vm 是空的，除非我删除一些数据

[HttpPost]
public async Task<IActionResult> CdsDeclarationSectionAndTag(CdsDeclarationSectionAndTagViewModel vm)
        {
        }

如果我这样改，fc也是null

[HttpPost]
public async Task<IActionResult> CdsDeclarationSectionAndTag(IFormCollection fc)
        {
        }

发布的表单数据看起来像这样(并且可以以 4 或 5 个递归级别结束)

Code: 42A FullName: Description: Declaration Entities[0].Code: 023 Entities[0].FullName: Acceptance (taxpoint) datetime Entities[0].Description: Acceptance (taxpoint) datetime Entities[0].IsDeleted: false Entities[1].Code: D026 Entities[1].FullName: LRN Entities[1].Description: LRN Entities[1].IsDeleted: false Entities[2].Code: D013 Entities[2].FullName: Declaration type Entities[2].Description: Declaration type Entities[2].IsDeleted: false Entities[3].Code: 109 Entities[3].FullName: Invoice total Entities[3].Description: Invoice total Entities[3].IsDeleted: false Entities[4].Code: 504 Entities[4].FullName: Specific circumstances indicator Entities[4].Description: Specific circumstances indicator Entities[4].IsDeleted: false Entities[5].Code: 131 Entities[5].FullName: Gross mass Entities[5].Description: Gross mass Entities[5].IsDeleted: false Entities[6].Code: 146 Entities[6].FullName: Total packages Entities[6].Description: Total packages Entities[6].IsDeleted: false Entities[7].Code: 61B Entities[7].FullName: Authentication Entities[7].Description: Authentication Entities[7].Entities[0].Code: 104 Entities[7].Entities[0].FullName: Signature/Authentication Entities[7].Entities[0].Description: Signature/Authentication Entities[7].Entities[0].IsDeleted: false Entities[7].IsDeleted: false Entities[8].Code: 02A Entities[8].FullName: Deferred Payment Entities[8].Description: Deferred Payment Entities[8].Entities[0].Code: D031 Entities[8].Entities[0].FullName: Deferment category code Entities[8].Entities[0].Description: Category code Entities[8].Entities[0].IsDeleted: false Entities[8].Entities[1].Code: D005 Entities[8].Entities[1].FullName: Deferment ID Entities[8].Entities[1].Description: ID Entities[8].Entities[1].IsDeleted: false Entities[8].Entities[2].Code: D006 Entities[8].Entities[2].FullName: Deferment Type Entities[8].Entities[2].Description: Type Entities[8].Entities[2].IsDeleted: false Entities[8].IsDeleted: false Entities[9].Code: 03A Entities[9].FullName: Additional Information Entities[9].Description: Additional Information Entities[9].Entities[0].Code: 226 Entities[9].Entities[0].FullName: Additional Information Statement code Entities[9].Entities[0].Description: Statement code Entities[9].Entities[0].IsDeleted: false ....

Answer 1

我在 this 上找到了答案线。 事实证明，默认情况下，您可以提交的表单值限制为 1024。

我在 Startup.cs 中使用了以下代码来更改限制，问题消失了，现在可以成功绑定(bind)

        services.Configure<FormOptions>(options =>
        {
            options.ValueCountLimit = int.MaxValue;
        });