Bind specified property of the WebAPI controller's model - asp.net

Question

I want to bind only specified property of the WebAPI controller's model and skip all another properties to the DefaultModelBinder.
For example I have json, which should be passed to the WebAPI controller:
{
prop1: 1,
prop2: "b",
prop3: "c",
currentTime: "Fri Feb 27 2015",
references:
[
{ name: "Name 1", type: "Info" },
{ name: "Name 2", type: "Warn" }
]
}
On the server-side there is a HttpPost action with the following signature:
[HttpPost]
public void SaveObject(ReferenceModel model)
{
...
}
Where ReferenceModel is:
public class ReferenceModel
{
public int Prop1 {get; set;}
public string Prop2 {get; set;}
public string Prop3 {get; set;}
public DateTime CurrentTime {get; set;}
public List<BaseReferenceItem> References {get; set;}
}
I need for custom bind of References property, because I want to initialize this property at the runtime by objects of derived types.
For example if I will get Prop1 with value 1 so I need to initialize this collection by objects of type DerivedReferenceType1:
Model.References = new List<BaseReferenceItem>()
{
new DerivedReferenceType1(){...},
new DerivedReferenceType1(){...}
}
If I will get Prop1 with value 2 - of type DerivedReferenceType2 and so on.
I've found potential solution in the ModelBinder, but I don't want to bind all properties at the model.
I know that it's can be easy implemented in the MVC model binders with the call of
base.BindModel(controllerContext, bindingContext);
But how to do it in WebAPI?
Thanks!

Answer 1

One possibility would be to write a custom JsonConverter to handle this situation:
public class MyConverter : JsonConverter
{
public override bool CanConvert(Type objectType)
{
return objectType == typeof(ReferenceModel);
}
public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
{
var jsonObject = JObject.Load(reader);
var result = new ReferenceModel();
serializer.Populate(jsonObject.CreateReader(), result);
result.References = new List<BaseReferenceItem>();
foreach (var obj in jsonObject.GetValue("references", StringComparison.InvariantCultureIgnoreCase))
{
if (result.Prop1 == 1)
{
result.References.Add(obj.ToObject<DerivedReferenceType1>(serializer));
}
else if (result.Prop1 == 2)
{
result.References.Add(obj.ToObject<DerivedReferenceType2>(serializer));
}
else
{
throw new NotSupportedException(result.Prop1 + " is not supported value for Prop1");
}
}
return result;
}
public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
{
throw new NotImplementedException();
}
}
and then you could decorate your main view model with this custom converter:
[JsonConverter(typeof(MyConverter))]
public class ReferenceModel
{
public int Prop1 { get; set; }
public string Prop2 { get; set; }
public string Prop3 { get; set; }
public DateTime CurrentTime { get; set; }
public List<BaseReferenceItem> References { get; set; }
}
or if you prefer to do this without modifying your view models you could always register your custom converter during the bootstrap process:
public static void Register(HttpConfiguration config)
{
// Web API routes
...
var jsonFormatter = config.Formatters.JsonFormatter;
jsonFormatter.SerializerSettings.Converters.Add(new MyConverter());
}