Get a list of JSON property names from a class to use in a query string

Question

If I have a C# model class that is used by JSON.net to bind data from a serialized JSON string, is there a way that I can create a query string from that class in order to m

Answer 1

In cases where the model is only partially annotated with [JsonProperty(PropertyName = "XXX")] attributes, or is annotated with data contract attributes, or has ignored properties, you can use Json.NET's own contract resolver to obtain the list of serialized property names. First, introduce the following extension method:

public static class JsonExtensions
{
    public static string [] PropertyNames(this IContractResolver resolver, Type type)
    {
        if (resolver == null || type == null)
            throw new ArgumentNullException();
        var contract = resolver.ResolveContract(type) as JsonObjectContract;
        if (contract == null)
            return new string[0];
        return contract.Properties.Where(p => !p.Ignored).Select(p => p.PropertyName).ToArray();
    }
}

Then, do:

// Allocate the relevant contract resolver. 
// Options are CamelCasePropertyNamesContractResolver() or DefaultContractResolver().
IContractResolver resolver = new DefaultContractResolver(); 

// Get properties
var propertyNames = resolver.PropertyNames(typeof(model));
var fields = "&fields=" + String.Join(",", propertyNames);

For resolver use CamelCasePropertyNamesContractResolver if you are camel casing your property names (which ASP.NET Core Web API does by default); otherwise use DefaultContractResolver.

Sample fiddle.