asp.net-mvc-4 - 模型绑定(bind)器 ValueProvider 附加到现有值 + MVC 4

Question

我的模型 Binder 中有以下方法:

protected override object CreateModel(ControllerContext controllerContext, ModelBindingContext bindingContext, Type modelType)
    {
        if (bindingContext.ValueProvider.GetValue("Id") == null)
        {
            string s = bindingContext.ValueProvider.GetValue("IsSoftDeleted").AttemptedValue;

            bool d = Convert.ToBoolean(s);
            return OrgFactory.Create(bindingContext.ValueProvider.GetValue("Caption").AttemptedValue,
                            bindingContext.ValueProvider.GetValue("NameInUse").AttemptedValue,
                            bindingContext.ValueProvider.GetValue("Description").AttemptedValue,
                            d, new Party());
        }
        else
        {
            return OrgFactory.Create(bindingContext.ValueProvider.GetValue("Caption").AttemptedValue,
                            bindingContext.ValueProvider.GetValue("NameInUse").AttemptedValue,
                            bindingContext.ValueProvider.GetValue("Description").AttemptedValue, 
                            Convert.ToBoolean(bindingContext.ValueProvider.GetValue("IsSoftDeleted").AttemptedValue));
        }
    }

在 create.cshtml View 中，如果我选中 IsSoftDeleted 的复选框，它在模型联编程序中的值将变为“true，false”，而它应该只为真。

你能告诉我做错了什么吗？

创建.cshtml

@using PartyBiz.Models.Objects
@model Organization

@using (Html.BeginForm("Create", "Organization", FormMethod.Post))
{

@Html.ValidationSummary(true)
<fieldset>
    <legend>Create a New Organization</legend>

    <div class="editor-label">
        @Html.LabelFor(model => model.Caption) 
        @Html.EditorFor(model => model.Caption, new { @class = "txt"}) 
        @Html.ValidationMessageFor(model => model.Caption) 
    </div> <br />

    <div class="editor-label">
        @Html.LabelFor(model => model.NameInUse)
        @Html.EditorFor(model => model.NameInUse, new { @class = "txt"}) 
        @Html.ValidationMessageFor(model => model.NameInUse)
    </div> <br />

    <div class="editor-label">
        @Html.LabelFor(model => model.Description)
        @Html.EditorFor(model => model.Description, new { @class = "txt"}) 
        @Html.ValidationMessageFor(model => model.Description)
    </div> 
    <div class="editor-label">
        @Html.LabelFor(O => O.IsSoftDeleted)
        @Html.EditorFor(O => O.IsSoftDeleted)
        @Html.ValidationMessageFor(O => O.IsSoftDeleted)
    </div>
    <br />
        <input type="submit" value="Create" />
</fieldset>
}  

Answer 1

您正在尝试使用 Convert.ToBoolean 方法将 true,false 的字符串值解析为 bool 值，这显然会失败。处理这种情况的正确方法是简单地使用框架中已经内置的内容 => 在将由 返回的 ValueProviderResult 上使用 ConvertTo 方法GetValue 方法。

就这样:

protected override object CreateModel(ControllerContext controllerContext, ModelBindingContext bindingContext, Type modelType)
{
    ValueProviderResult isSoftDeletedValue = bindingContext.ValueProvider.GetValue("IsSoftDeleted");
    // use the built-in method into the model binder to correctly convert
    // the value to the corresponding boolean type 
    bool isSoftDeleted = (bool)isSoftDeletedValue.ConvertTo(typeof(bool));

    if (bindingContext.ValueProvider.GetValue("Id") == null)
    {

        return OrgFactory.Create(
            bindingContext.ValueProvider.GetValue("Caption").AttemptedValue,
            bindingContext.ValueProvider.GetValue("NameInUse").AttemptedValue,
            bindingContext.ValueProvider.GetValue("Description").AttemptedValue,
            isSoftDeleted, 
            new Party()
        );
    }

    return OrgFactory.Create(
        bindingContext.ValueProvider.GetValue("Caption").AttemptedValue,
        bindingContext.ValueProvider.GetValue("NameInUse").AttemptedValue,
        bindingContext.ValueProvider.GetValue("Description").AttemptedValue, 
        isSoftDeleted
    );
}

就是这样:

var isSoftDeletedValue = bindingContext.ValueProvider.GetValue("IsSoftDeleted");
bool isSoftDeleted = (bool)isSoftDeletedValue.ConvertTo(typeof(bool));

请注意，我们在这里调用 ValueProviderResult 上的底层 ConvertTo 方法，它知道如何正确处理这种情况。