如果任何属性为空，如何在匿名类中设置默认值；

Question

I have a class as following.

public class CommonResponse<T>
{
    public HttpStatusCode ResponseCode { get; set; }
    public string ResponseMessage { get; set; }
    public T data { get; set; }
}

there are the following option.

//1. 
CommonResponse<string> obj1=new CommonResponse<string>(){ResponseCode=200, ResponseMessage="OK", data=null};
//2. 
CommonResponse<string> obj2=new CommonResponse<class1>(){ResponseCode=200, ResponseMessage="OK", data=new class1{p1="", p2=null, p3=null}};
//3. 
CommonResponse<string> obj3=new CommonResponse<class2>(){ResponseCode=200, ResponseMessage="OK", data=null};

i am looking a code that convert every null value into default value. the default values are as following

1 type(string)=string.empty;

2 type(int)=0;

etc.

i am trying the following code. but it is not working.

public class CommonResponse<T>
{
    private T _data { get; set; }

    public HttpStatusCode ResponseCode { get; set; }
    public string ResponseMessage { get; set; }



    public T data
    {
        get
        {
            if (_data != null)
            {
                PropertyInfo[] properties =
                _data.GetType().GetProperties(BindingFlags.Public | BindingFlags.Instance);

                foreach (var item in properties)
                {
                    if (item.PropertyType == typeof(string))
                    {
                        var value = item.GetValue(_data, null);

                        if (value == null)
                        {
                            item.SetValue(_data, Convert.ChangeType(string.Empty, item.PropertyType), null);
                        }
                    }
                    if (item.PropertyType == typeof(int))
                    {
                        var value = item.GetValue(_data, null);

                        if (value == null)
                        {
                            item.SetValue(_data, Convert.ChangeType(0, item.PropertyType), null);
                        }
                    }
                }

                return _data;
            }
            else
            {

                return (T)Convert.ChangeType(string.Empty, typeof(T));
            }
        }
        set
        {
            _data = value;
        }
    }
}

i need the following output

//1.
obj1={ResponseCode=200, ResponseMessage="OK", data=""};

//2.
obj2={ResponseCode=200, ResponseMessage="OK", data=new class1{p1="", p2="", p3=0}};

//3.
obj3={ResponseCode=200, ResponseMessage="OK", data=""};

for example

public class class1
{
    public string p1{get;set;}
    public string p1{get;set;}
    public int? p3{get;set;}
}

CommonResponse<string> obj2=new CommonResponse<class1>(){ResponseCode=200, ResponseMessage="OK", data=new class1{p1="hello", p2=null, p3=null}};
var json = new JavaScriptSerializer().Serialize(obj2);

Console.WriteLine(json);

the output is as following

{"ResponseCode":"200", "ResponseMessage":"OK", data:{"p1":"hello", "p2":null, "p3": null}}

There are two null fields p2 and p3

I need that every null value convert into empty string. the desired output is as following.

{"ResponseCode":"200", "ResponseMessage":"OK", data:{"p1":"hello", "p2":"", "p3": "0"}}

Answer 1

It seems you are not using set properly, so data is always null.

You should change

set
{
    _data = data;
}

to:

set
{
    _data = value;
}