在ASP.NET C#中使用动态in级联DropDownList

// 假设有两个DropDownList控件，分别为ddlParent和ddlChild

protected void Page_Load(object sender, EventArgs e)
{
    if (!IsPostBack)
    {
        // 绑定父级DropDownList的数据源
        ddlParent.DataSource = GetParentOptions();
        ddlParent.DataTextField = "Text";
        ddlParent.DataValueField = "Value";
        ddlParent.DataBind();
    }
}

protected void ddlParent_SelectedIndexChanged(object sender, EventArgs e)
{
    // 获取所选父级选项的值
    string parentId = ddlParent.SelectedValue;

    // 根据父级选项的值查询子级选项的数据源
    var childOptions = GetChildOptions(parentId);

    // 绑定子级DropDownList的数据源
    ddlChild.DataSource = childOptions;
    ddlChild.DataTextField = "Text";
    ddlChild.DataValueField = "Value";
    ddlChild.DataBind();
}

private List<Option> GetParentOptions()
{
    // 从数据源获取父级选项数据
    // 这里可以使用数据库查询、API接口调用等方式获取数据
    // 返回一个包含Text和Value属性的Option列表
    // 示例数据：
    return new List<Option>
    {
        new Option { Text = "父级选项1", Value = "1" },
        new Option { Text = "父级选项2", Value = "2" },
        new Option { Text = "父级选项3", Value = "3" }
    };
}

private List<Option> GetChildOptions(string parentId)
{
    // 根据父级选项的值查询子级选项的数据源
    // 这里可以使用数据库查询、API接口调用等方式获取数据
    // 返回一个包含Text和Value属性的Option列表
    // 示例数据：
    if (parentId == "1")
    {
        return new List<Option>
        {
            new Option { Text = "子级选项1-1", Value = "1-1" },
            new Option { Text = "子级选项1-2", Value = "1-2" },
            new Option { Text = "子级选项1-3", Value = "1-3" }
        };
    }
    else if (parentId == "2")
    {
        return new List<Option>
        {
            new Option { Text = "子级选项2-1", Value = "2-1" },
            new Option { Text = "子级选项2-2", Value = "2-2" },
            new Option { Text = "子级选项2-3", Value = "2-3" }
        };
    }
    else if (parentId == "3")
    {
        return new List<Option>
        {
            new Option { Text = "子级选项3-1", Value = "3-1" },
            new Option { Text = "子级选项3-2", Value = "3-2" },
            new Option { Text = "子级选项3-3", Value = "3-3" }
        };
    }
    else
    {
        return new List<Option>();
    }
}

public class Option
{
    public string Text { get; set; }
    public string Value { get; set; }
}