Capture exception during request deserialization in WebAPI C#

Question

I\'m using WebAPI v2.2 and I am getting WebAPI to deserialise JSON onto an object using [FromBody] attribute. The target class of the deserialisation has a [OnDeserialized]

Answer 1

I've written up a filter (as suggested in various comments) that checks the ModelState and throws an exception if serialization errors did occur. Beware though, that this may not contain only serialization exceptions - that could be adjusted by specifing the concrete exception type in the Select statement.

public class ValidModelsOnlyFilter : ActionFilterAttribute
{
    public override void OnActionExecuting(HttpActionContext actionContext)
    {
        if (actionContext.ModelState.IsValid)
        {
            base.OnActionExecuting(actionContext);
        }
        else
        {
            var exceptions = new List();

            foreach (var state in actionContext.ModelState)
            {
                if (state.Value.Errors.Count != 0)
                {
                    exceptions.AddRange(state.Value.Errors.Select(error => error.Exception));
                }
            }

            if (exceptions.Count > 0)
                throw new AggregateException(exceptions);
        }
    }
}

I suggest binding this filter on a global scope. I really can't fathom why it should be ok to ignore deserialization exceptions.