Updating the name of a Json Property in a class-CodePudding

I am trying to update the name of a property in a Json serializable class that is already released, so I need to make it backwards compatible.

public class myClass
{
    //[JsonIgnore] - now old json files can't be read, so this won't work...
    //[JsonProperty(ReferenceLoopHandling = ReferenceLoopHandling.Error)] - didn't do anything
    //[JsonProperty(nameof(NewName)] - throws error - "That already exists"
    [Obselete("Use NewName instead")]
    public List<string> OldName { get => newName; set => newName = value; }

    public List<string> NewName { get; set; } = new List<string>();
}

And I use it like this:

[Test]
public void test()
{
    var foo = new myClass()
    {
        OldName = { "test" },
    };

    var bar = JsonConvert.SerializeObject(foo);
    var result = JsonConvert.DeserializeObject(bar, typeof(myClass));
}

When I look at the value in result.NewName, I find this list: {"test", "test"}, but I expected this list: {"test"}

The desired behavior:

If someone is already using OldName in their code, they get an obselete warning
if someone parses an old json file with OldName in it, it's correctly mapped to NewName
New json files that are created use NewName, and OldName isn't found anywhere in the json file
In no case is the value deserialized twice and put in the same list

How would you accomplish this?

CodePudding user response：

This works using System.Text.Json.

            var foo = new myClass()
            {
                OldName = { "test" },
            };

            var bar = JsonSerializer.Serialize<myClass>(foo);
            var result = JsonSerializer.Deserialize<myClass>(bar);

CodePudding user response：

Try this

var foo = "{\"OldName\":[\"old test\"]}";
var fooN = "{\"NewName\":[\"new test\"]}";
var result = JsonConvert.DeserializeObject(foo, typeof(myClass));
//or
var result = JsonConvert.DeserializeObject(fooN, typeof(myClass));

var json = JsonConvert.SerializeObject(result);

json result:

{"NewName":["new test"]}
//or
{"NewName":["old test"]}

class

public class myClass
{
   [JsonProperty(NullValueHandling = NullValueHandling.Ignore)]
    public List<string> OldName {

        get {return null; }
        set {NewName=value;} 
    }

    public List<string> NewName {get; set;}
}