UPDATE: for the tl;dr version skip to the bottom
I have a pretty simple subclass of JsonConverter that I'm using with Web API:
public class DbGeographyJsonConverter : JsonConverter
{
public override bool CanConvert(Type type)
{
return typeof(DbGeography).IsAssignableFrom(type);
}
public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
{
var value = (string)reader.Value;
if (value.StartsWith("POINT", StringComparison.OrdinalIgnoreCase))
{
return DbGeography.PointFromText(value, DbGeography.DefaultCoordinateSystemId);
}
else if (value.StartsWith("POLYGON", StringComparison.OrdinalIgnoreCase))
{
return DbGeography.FromText(value, DbGeography.DefaultCoordinateSystemId);
}
else //We don't want to support anything else right now.
{
throw new ArgumentException();
}
}
public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
{
serializer.Serialize(writer, ((DbGeography)value).AsText());
}
}
The problem is, after ReadJson
returns the application never returns a bound object to the action method as it appears to be stuck in an infinite validation loop.
Here's the top of the call stack when I pause execution:
System.Web.Http.dll!System.Web.Http.Metadata.Providers.AssociatedMetadataProvider.GetMetadataForPropertiesImpl.AnonymousMethod__0() Line 40 C#
System.Web.Http.dll!System.Web.Http.Metadata.ModelMetadata.Model.get() Line 85 C#
System.Web.Http.dll!System.Web.Http.Validation.DefaultBodyModelValidator.ValidateNodeAndChildren(System.Web.Http.Metadata.ModelMetadata metadata, System.Web.Http.Validation.DefaultBodyModelValidator.ValidationContext validationContext, object container) Line 94 C#
System.Web.Http.dll!System.Web.Http.Validation.DefaultBodyModelValidator.ValidateProperties(System.Web.Http.Metadata.ModelMetadata metadata, System.Web.Http.Validation.DefaultBodyModelValidator.ValidationContext validationContext) Line 156 C#
System.Web.Http.dll!System.Web.Http.Validation.DefaultBodyModelValidator.ValidateNodeAndChildren(System.Web.Http.Metadata.ModelMetadata metadata, System.Web.Http.Validation.DefaultBodyModelValidator.ValidationContext validationContext, object container) Line 130 C#
System.Web.Http.dll!System.Web.Http.Validation.DefaultBodyModelValidator.ValidateElements(System.Collections.IEnumerable model, System.Web.Http.Validation.DefaultBodyModelValidator.ValidationContext validationContext) Line 176 C#
After that, the DefaultBodyModelValidator.Validation* pattern of calls repeats over and over and over again. Everytime I pause execution, it appears to be at about the same depth, so it doesn't appear to be getting recursively deeper.
If I force the JsonConverter to return null
, control returns to the API controller action method, I'm assuming because there's nothing to validate.
I don't have the brain juices left to figure this one out. What am I doing wrong?
UPDATE: With brain juices somewhat replenished, I've stepped through most of the code and it appears that when validating the model the DefaultBodyModelValidator
is drilling way down into the SqlTypesAssembly
and getting stuck in a loop reading attributes somewhere. I don't really care to find out exactly where because I don't want the DefaultBodyModelValidator
drilling into DbGeography
type instances to start with.
There's no reason for model validation to drill down into the DbGeography
class. I need to figure out how to get the MediaTypeFormatterCollection.IsTypeExcludedFromValidation
method to return true for typeof(DbGeography)
, which will cause the DefaultBodyModelValidator
to perform shallow validation on any DbGeography
instances. So now the question at hand is- how do I exclude a type from model validation? The ShouldValidateType
method of DefaultBodyModelValidator
is marked virtual, but is there not a simple way to add an excluded type at startup?
See Question&Answers more detail:
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