Generate inheritance information manually

[SebastianStehle]

Hi,

I have a typical application with multiple layers and separate data structures: DTOs in my Api Layer, Business Objects in my Domain Layer and so on.

But one part of my application is a rule engine, like "When X happens (Trigger) send a tweet (Action)". So far I use inheritance for the different actions and define this inheritance in my DTOs. I would like to add plugins for the actions and therefore I have to break the architecture here a little bit. The goal is to define Action Definitions in your plugin and everything else is generated from it, e.g.

public sealed class SlackAction : RuleAction
{
    [Required]
    [Display(Name = "Webhook Url", Description = "The slack webhook url.")]
    public Uri WebhookUrl { get; set; }

    [Required]
    [Display(Name = "Text", Description = "The text that is sent as message to slack.")]
    public string Text { get; set; }
}

The question is: How can I generate the inheritance definition for it? I am had a look to the interfaces like IOperationProcessor and so but I can just not find the right information.

[RicoSuter]

Inheritance is generated here:
https://github.com/RSuter/NJsonSchema/blob/master/src/NJsonSchema/Generation/JsonSchemaGenerator.cs#L659

More or less hard-coded... maybe we can provide add an extension point somehow? Maybe you can inherit from the generator class and modify/extend this?

Maybe we should wait until this pr which changes the allof generation is merged:
RicoSuter/NJsonSchema#733

[SebastianStehle]

Thanks for your response. I also had a look to this class but there is no extension point.

Wait, I can just write a ITypeMapper, right?

[SebastianStehle]

Mhm,

public class RuleActionSchema : ITypeMapper
{
	public Type MappedType ...

	public bool UseReference ...

	public Task GenerateSchemaAsync(JsonSchema4 schema, TypeMapperContext context)
	{
		var defaultSchema = context.JsonSchemaGenerator.GenerateAsync();
		
		Copy(defaultSchema, schema); // This sucks :(
		
		AddInheritedSchemas(schema);
	}
}

[RicoSuter]

Cant you just add the additional types to the document’s definition and reference the base schema in allof and maybe update the discriminator mappings of the base schema (in a document processor)?

[SebastianStehle]

This was also my idea, but how can I find the correct schema in the document processor?

[RicoSuter]

The contest has a resolver which can resolve the generated schema for a type i think

[SebastianStehle]

Thanks, it works:

public sealed class RuleActionProcessor : IDocumentProcessor
{
    public async Task ProcessAsync(DocumentProcessorContext context)
    {
        var schema = context.SchemaResolver.GetSchema(typeof(RuleAction), false);

        var discriminator = new OpenApiDiscriminator
        {
            JsonInheritanceConverter = new JsonInheritanceConverter("actionType"),
			PropertyName = "actionType"
        };

        schema.DiscriminatorObject = discriminator;
        schema.Properties["actionType"] = new JsonProperty
        {
            Type = JsonObjectType.String,
			IsRequired = true
        };

        foreach (var derived in ActionConfig.Actions)
        {
            await context.SchemaGenerator.GenerateAsync(derived, context.SchemaResolver);
        }
}
}