C# &引用；{"；数据源是无效类型。它必须是IListSource、IEnumerable或IDataSource。"；}"；装订时

我正在尝试使用

JsonConvert.DeserializeObject

将asp:dropdownlist与json数据绑定，它正在获取完整的json，但我想将其与json数据的内部数组绑定。获取的数据的类型为

{System.Collections.ListDictionaryInternal}

，并引发异常

{“数据源是无效的类型。绑定时它必须是IListSource、IEnumerable或IDataSource。”}

ddlCategoryMain

完全绑定

ddlCategoryMain\u SelectedIndexChanged上绑定
ddlCategorySub
时出现异常

以下是json数据：

 {
  "Category": [
    {
      "MainCategory": "Biography",
      "SubCategory": [
        "Historical",
        "Political",
        "Military",
        "Musician"
      ]
    },
    {
      "MainCategory": "Business",
      "SubCategory": [
        "Self-Employed",
        "Taxation",
        "Personal Finance",
        "Organisational Behaviour"
      ]
    },
    {
      "MainCategory": "Computers & Internet",
      "SubCategory": [
        "Computer Programing",
        "Web Design",
        "Mobile Phones",
        "Computer Hardware",
        "Operating Systems"
      ]
    }
  ]
}

以下是DataEntity：

public class bookcategoryDE
{
    public List<Category> Category { get; set; }
}
public class Category
{
    public int CategoryID { get; set; }
    public string MainCategory { get; set; }
    public List<string> SubCategory { get; set; }
}

公共类图书分类
{
公共列表类别{get；set；}
}
公共类类别
{
public int CategoryID{get；set；}
公共字符串MainCategory{get；set；}
公共列表子类别{get；set；}
}

这是我的密码：

（.aspx）：







（.cs）：

受保护的无效页面加载（对象发送方，事件参数e）
{
如果（！Page.IsPostBack）
{
var JsonBookCategory=ReadJson（Server.MapPath（“~/Json/Category.Json”）；
ddlCategoryMain.DataSource=JsonBookCategory.Category；
ddlCategoryMain.DataBind（）；
}
}
public T ReadJson（字符串JsonPath）
{
使用（StreamReader r=newstreamreader（JsonPath））
{
T keys=JsonConvert.DeserializeObject（r.ReadToEnd（））；
返回键；
}
}
受保护的无效ddlCategoryMain\u SelectedIndexChanged（对象发送方，事件参数e）
{
var JsonBookCategory=ReadJson（Server.MapPath（“~/Json/Category.Json”）；
ddlCategorySub.DataSource=JsonBookCategory；
ddlCategorySub.DataBind（）；
}
受保护的无效ddlCategoryMain\u SelectedIndexChanged（对象发送方，事件参数e）
{
var JsonBookCategory=ReadJson（Server.MapPath（“~/Json/Category.Json”）；
//JsonBookCategory不是IListSource、IEnumerable或IDataSource（比如说exception）
//ddlCategorySub.DataSource=JsonBookCategory；
var selectedCategoryName=ddlCategoryMain.SelectedValue；
var selectedCategory=JsonBookCategory.Category.Where（c=>c.maincegory==selectedCategoryName.singleOrdFeature（）；
如果（SelectedCateLogy！=null）
{
ddlCategorySub.DataSource=selectedCategory.Category；
ddlCategorySub.DataBind（）；
}
}

也许您的下拉配置应该是

       <asp:DropDownList ID="ddlCategoryMain" runat="server" DataTextField="MainCategory" DataValueField="MainCategory"
        AutoPostBack="true" OnSelectedIndexChanged="ddlCategoryMain_SelectedIndexChanged">
    </asp:DropDownList>
    <br />
    <br />
    <asp:DropDownList ID="ddlCategorySub" runat="server" DataTextField="MainCategory" DataValueField="MainCategory"></asp:DropDownList>






No，我想在“main category”索引更改中将其与“sub category”绑定。使用此命令：“var selectedCategory JsonBookCategory.category.Where（c=>c.maincegory==selectedCategoryName）。singleOrdfilet（）；”这是相同的异常我认为有构建错误，并运行旧代码。。我更新了post
ReadJson
方法返回的是什么？
protected void Page_Load(object sender, EventArgs e)
    {
        if (!Page.IsPostBack)
        {



            var JsonBookCategory = ReadJson<bookcategoryDE>(Server.MapPath("~/Json/Category.json"));
            ddlCategoryMain.DataSource = JsonBookCategory.Category;
            ddlCategoryMain.DataBind();
        }
    }

    public T ReadJson<T>(string JsonPath)
    {
        using (StreamReader r = new StreamReader(JsonPath))
        {
            T keys = JsonConvert.DeserializeObject<T>(r.ReadToEnd());
            return keys;
        }
    }

    protected void ddlCategoryMain_SelectedIndexChanged(object sender, EventArgs e)
    {
        var JsonBookCategory = ReadJson<bookcategoryDE>(Server.MapPath("~/Json/Category.json"));
        ddlCategorySub.DataSource = JsonBookCategory;
        ddlCategorySub.DataBind();
    }

protected void ddlCategoryMain_SelectedIndexChanged(object sender, EventArgs e)
{
    var JsonBookCategory = ReadJson<bookcategoryDE>(Server.MapPath("~/Json/Category.json"));
    // JsonBookCategory is not IListSource, IEnumerable, or IDataSource(like say exception)
    //ddlCategorySub.DataSource = JsonBookCategory;
    var selectedCategoryName  = ddlCategoryMain.SelectedValue;
    var selectedCategory = JsonBookCategory.Category.Where(c => c.MainCategory== selectedCategoryName).SingleOrDefult();
    if(selectedCateogry != null)
    {
     ddlCategorySub.DataSource = selectedCategory.Category;
     ddlCategorySub.DataBind();
    }

}

       <asp:DropDownList ID="ddlCategoryMain" runat="server" DataTextField="MainCategory" DataValueField="MainCategory"
        AutoPostBack="true" OnSelectedIndexChanged="ddlCategoryMain_SelectedIndexChanged">
    </asp:DropDownList>
    <br />
    <br />
    <asp:DropDownList ID="ddlCategorySub" runat="server" DataTextField="MainCategory" DataValueField="MainCategory"></asp:DropDownList>