NJsonSchema C# - Change Generated Value Type

Question

I am using NJsonSchema CsharpGenerator 10.1.24 and have the below schema I am using to generate a POCO:

    "description": "schema validating people and vehicles", 
    "$schema": "http://json-schema.org/draft-04/schema#",
    "type": "object",
    "required": [ "oneOf" ],
    "properties": { "oneOf": [
        {
            "firstName": {"type": "string"}, 
            "lastName": {"type": "string"}, 
            "sport": {"type": "string"}
        }, 
        {
            "vehicle": {"type": "string"}, 
            "price":{"type": "number"} 
        }
     ]
   }
}

How can I get the generated C# class to have a decimal type for price instead of the default double?

public double Price { get; set;}

I tried using a custom static method with the generator settings JsonSerializerSettingsTransformationMethod property but nothing changed.

Answer 1

You can try this,

Create CustomTypeResolver

public class CustomTypeResolver : CSharpTypeResolver
{
    ...

    public override string Resolve(JsonSchema schema, bool isNullable, string typeNameHint)
    {
        if (schema == null)
        {
            throw new ArgumentNullException(nameof(schema));
        }

        schema = GetResolvableSchema(schema);

        if (schema == ExceptionSchema)
        {
            return "System.Exception";
        }

        var type = schema.ActualTypeSchema.Type;

        if (type.HasFlag(JsonObjectType.Number))
        {
            return isNullable ? "decimal?" : "decimal"; ;
        }

        return base.Resolve(schema, isNullable, typeNameHint);
    }

    ...
}

Generate the class,

var jsonSchema = File.ReadAllText("json1.json");
var schema = JsonSchema.FromJsonAsync(jsonSchema).GetAwaiter().GetResult();
var settings = new CSharpGeneratorSettings();
var typeResolver = new CustomTypeResolver(settings);
var generator = new CSharpGenerator(schema, settings, typeResolver);
var code = generator.GenerateFile();