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How do I integrate custom JSON converters with the default MvvmCross plugins


Integrating custom JSON converters with the default MvvmCross plugins involves several steps. Here's a detailed guide on how to achieve this:

Step 1: Understand MvvmCross JSON Plugin

MvvmCross uses the Newtonsoft.Json library for JSON serialization and deserialization through its JSON plugin. This plugin provides a standard way to handle JSON data in your application[1][5].

Step 2: Create a Custom JSON Converter

To integrate custom JSON converters, you need to create a class that inherits from `JsonConverter` or uses `JsonSerializerSettings`. Here's an example of creating a custom converter: 

csharp
public class MyJsonConverter : JsonConverter
{
    public override bool CanConvert(Type objectType)
    {
        // Implement logic to determine if this converter can handle the type
        return objectType == typeof(YourCustomType);
    }

    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
    {
        // Implement deserialization logic
        if (reader.TokenType == JsonToken.StartObject)
        {
            var jObject = JObject.Load(reader);
            // Convert jObject to YourCustomType
            return new YourCustomType { /* Initialize properties */ };
        }
        throw new JsonException("Unexpected token type");
    }

    public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
    {
        // Implement serialization logic
        var yourCustomObject = (YourCustomType)value;
        writer.WriteStartObject();
        // Write properties to JSON
        writer.WritePropertyName("Property1");
        writer.WriteValue(yourCustomObject.Property1);
        writer.WriteEndObject();
    }
}

Step 3: Configure JsonSerializerSettings

Alternatively, you can configure `JsonSerializerSettings` to include custom converters or settings. Here's how you can do it: 

csharp
public class MyJsonConverter : IMvxJsonConverter
{
    private static readonly JsonSerializerSettings Settings;

    static MyJsonConverter()
    {
        Settings = new JsonSerializerSettings
        {
            ReferenceLoopHandling = Newtonsoft.Json.ReferenceLoopHandling.Serialize,
            Converters = new List { new MyJsonConverter() },
            DateFormatHandling = DateFormatHandling.IsoDateFormat,
            PreserveReferencesHandling = PreserveReferencesHandling.Objects
        };
    }

    public T DeserializeObject(string inputText)
    {
        return JsonConvert.DeserializeObject(inputText, Settings);
    }

    public string SerializeObject(object toSerialize)
    {
        return JsonConvert.SerializeObject(toSerialize, Formatting.None, Settings);
    }

    public object DeserializeObject(Type type, string inputText)
    {
        return JsonConvert.DeserializeObject(inputText, type, Settings);
    }
}

Step 4: Register the Custom Converter

To use your custom converter with MvvmCross, you need to register it in the `App.cs` file. Replace the default `MvxJsonConverter` with your custom one: 

csharp
public class App : MvxApplication
{
    public override void Initialize()
    {
        base.Initialize();

        // Register custom converter
        Mvx.RegisterType();
    }
}

Step 5: Use the Custom Converter

Now you can use the custom converter throughout your application. For example, to serialize an object: 

csharp
var serializer = Mvx.IoCProvider.Resolve();
var exampleObject = new ExampleObject { /* Initialize properties */ };
var jsonText = serializer.SerializeObject(exampleObject);

By following these steps, you can effectively integrate custom JSON converters with the default MvvmCross plugins, allowing for more flexible and customized JSON serialization and deserialization in your application.

Citations:
[1] https://www.mvvmcross.com/documentation/plugins/json
[2] https://pmichaels.net/2014/12/25/mvvmcross-overriding-the-default-plugins/
[3] https://learn.microsoft.com/en-us/dotnet/standard/serialization/system-text-json/converters-how-to
[4] https://stackoverflow.com/questions/18168455/creating-custom-visibility-converter
[5] https://www.nuget.org/packages/MvvmCross.Plugin.Json/
[6] https://www.mvvmcross.com/documentation/advanced/customizing-using-App-and-Setup
[7] https://www.mvvmcross.com/documentation/fundamentals/data-binding
[8] https://stackoverflow.com/questions/21094633/mvvmcross-keep-program-settings-using-file-plugin-and-json-serialize-deserialize