Json.Net property name changed after serialization

Question

Lets say I have some class that I have previously serialized with Json.Net

public class BillingAddress
{
    public string BillingCity { get; set; }
    public string BillingState { get; set; }
    public string BillingStreet { get; set; }
    public string BillingZip { get; set; }
}

However, I had to go back and change BillingStreet to BillingStreet1, and then again later on to BillingStreetA. I am trying to find a way in Json.Net to support either an attribute or custom converter that can deserialize a property that has been known as a different name previously, and also supports having more than one different previous name (such as in my example).

I have a custom converter that relies on an attribute as follows:

[JsonVersionedPropertyName("BillingStreetA", "BillingStreet1")]
public string BillingStreet { get; set; }



public class VersionedPropertyNameConverter : JsonConverter
{
    public override bool CanConvert(Type objectType)
    {
        //return objectType.IsClass;
        return (objectType == typeof(IPaymentMethod));
    }

    public override bool CanWrite
    {
        get { return false; }
    }

    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
    {
        object instance = objectType.GetConstructor(Type.EmptyTypes).Invoke(null);
        PropertyInfo[] props = objectType.GetProperties();
        var versionedProps = props.Where(x => Attribute.IsDefined(x, typeof(JsonVersionedPropertyName)));

        JObject jo = JObject.Load(reader);
        foreach (JProperty jp in jo.Properties())
        {
            foreach (var versProp in versionedProps)
            {
                var attrs = versProp.GetCustomAttributes(true);
                foreach (var att in attrs)
                {
                    var versionedProp = att as JsonVersionedPropertyName;
                    if (versionedProp != null)
                    {
                        var versions = versionedProp.VersionedNames;
                        PropertyInfo prop = props.FirstOrDefault(pi => 
                            pi.CanWrite && (string.Equals(pi.Name, jp.Name, StringComparison.OrdinalIgnoreCase) || versions.Contains(jp.Name)));
                        if (prop != null)
                            prop.SetValue(instance, jp.Value.ToObject(prop.PropertyType, serializer));
                    }
                }
            }
        }

        return instance;
    }

    public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
    {
        throw new NotImplementedException();
    }
}

However, when I try to use this converter with another converter, my my entire deserialization fails. I am trying to figure out if theres a better way to do this (versioned property names) instead of what I have above.

TheSoftwareJedi · Accepted Answer · 2018-10-09 20:38:58Z

You're close. Something like this works. I'll leave it as an excercise to genericize it :):

public class OninaigConverter : JsonConverter
{
    private readonly Dictionary<string, string> _propertyMappings = new Dictionary<string, string>
    {
        {"BillingStreetA", "BillingStreet"},
        {"BillingStreet1", "BillingStreet"}
    };

    public override bool CanWrite => false;

    public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
    {
        throw new NotImplementedException();
    }

    public override bool CanConvert(Type objectType)
    {
        return objectType.GetTypeInfo().IsClass;
    }

    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
    {
        object instance = Activator.CreateInstance(objectType);
        var props = objectType.GetTypeInfo().DeclaredProperties.ToList();

        JObject jo = JObject.Load(reader);
        foreach (JProperty jp in jo.Properties())
        {
            if (!_propertyMappings.TryGetValue(jp.Name, out var name))
                name = jp.Name;

            PropertyInfo prop = props.FirstOrDefault(pi =>
                pi.CanWrite && pi.GetCustomAttribute<JsonPropertyAttribute>().PropertyName == name);

            prop?.SetValue(instance, jp.Value.ToObject(prop.PropertyType, serializer));
        }

        return instance;
    }
}

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