MissingMemberHandling.Error force exception when deserializing the HTTP body

Question

I am creating a restful web-service using .net and Newtonsoft for serialization/deserialization.

The aim is to force exceptions (preferably HTTP 400) when a required property is not included in the request.

1. Serializer configuration

   config.Formatters.JsonFormatter.SerializerSettings = new JsonSerializerSettings {
           MissingMemberHandling = MissingMemberHandling.Error,
           Error = delegate (object x, ErrorEventArgs error) {
               System.Diagnostics.Debug.WriteLine (error.ErrorContext.Error);
               throw new Exception("");
       }
   };
   

2. Model

   [DataContract]
   public class MyObject {
       [JsonProperty(PropertyName = "id", Required = Required.Always)]
       public string Id { get; set; }
   }
   

3. Restful end-point

   public IHttpActionResult MyAction([FromBody]MyObject request)
   

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Testing:

When a request is fired the flow goes like this:

1. The break point of the error delegate hits ('1. Serializer configuration') and i am able to see the error log. The error is 'swallowed' and the execution is continuing in the controller.
2. The execution fails in another part of the web service.

Hence... i am able to capture the error using the delegate, but not able to propagate it (not setting a delegate at all again does not make a difference).

Isn't it fair to expect that by setting the 'MissingMemberHandling.Error', i should actually see an error in my controller?

Isn't it fair to expect that by indicating a property as 'required', i should actually see an error in my controller?

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Goal:

Instead of silently failing, I would like to force an error when the HTTP body deserialzation fails.

Answer 1

The only legit way i could found to capture missing property errors was to check the ModelState object.

if (!ModeState.IsValid) {
    return BadRequest(ModelState);
}

This was added at the top of the controller.

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Update - FluentValidation can be used to:

• Decouple the validation logic from the actual model.
• Define more complex validation rules.
• Automatically return a BadRequest response if the validation fails (which was the initial ask)