如何动态定义匿名对象属性？

Question

我正在我的网站上创建一个小应用程序,以使用API​​请求获取用户信息.

[HttpGet("GetUserInfo/{user_id}/{fields?}")]
public IActionResult GetUserInfo(string user_id, params string[] fields)
{
    var userProfile = _userManager.GetUserProfile(user_id);

    if (userProfile == null)
    {
        return Ok(null);
    }

    var userInfo = new
    {
        id = userProfile.UserId,
        email = userProfile.Email,
        name = userProfile.Name,
        // I don't want to define a null property here:
        picture_url = fields.Contains("picture_url") ? "path" : null
    };

    if (fields.Contains("picture_url"))
    {
        userInfo.picture_url = "";
    }

    return Ok(userInfo);
}

当一个请求是有效的,则它返回其包含3个属性默认JSON对象:id,email,和name.

现在,我想检查一下,如果请求想要获得有关此用户的更多信息,就像picture_url.所以,我试过了:

if (fields.Contains("picture_url"))
{
    // error in this line
    userInfo.picture_url = "path";
}

'<anonymous type:string id,string email,string name>'不包含'picture_url'的定义,也没有扩展方法'picture_url'接受类型'<anonymous type的第一个参数:string id,string email,string name >'可以找到(你是否错过了使用指令或汇编引用？)

如何动态地向匿名对象添加一些属性？

Answer 1

匿名类型是不可变的,您只能在创建实例时创建和设置属性.这意味着您需要创建所需的确切对象.所以你可以这样做:

if (fields.Contains("picture_url"))
{
    return Ok(new
    {
        id = userProfile.UserId,
        email = userProfile.Email,
        name = userProfile.Name,
        picture_url = "path"
    });
}

return Ok(new
{
    id = userProfile.UserId,
    email = userProfile.Email,
    name = userProfile.Name
});

另一种选择是使用a Dictionary<string, object>.例如:

var userInfo = new Dictionary<string, object>
{
    {"id", userProfile.UserId},
    {"email", userProfile.Email},
    {"name", userProfile.Name}
};

if (fields.Contains("picture_url"))
{
    // error in this line
    userInfo.Add("picture_url", "path");
}

return Ok(userInfo);

此对象将序列化为相同的JSON结构:

{"id":1,"email":"email@somewhere.com","name":"Bob","picture_url":"path"}