System.InvalidOperationException when getting a List with an ApiController

System.InvalidOperationException when getting a List with an ApiController

When I visit the /WeedAPI/ URL in my application, I get the following
error. How do I get my web API working? (Controller, model code to follow)
Full error detail:
<Error>
<Message>An error has occurred.</Message>
<ExceptionMessage>
The 'ObjectContent`1' type failed to serialize the response body
for content type 'application/xml; charset=utf-8'.
</ExceptionMessage>
<ExceptionType>System.InvalidOperationException</ExceptionType>
<StackTrace/>
<InnerException>
<Message>An error has occurred.</Message>
<ExceptionMessage>
Type 'WeedCards.Models.Weed' cannot be serialized. Consider
marking it with the DataContractAttribute attribute, and
marking all of its members you want serialized with the
DataMemberAttribute attribute. If the type is a collection,
consider marking it with the CollectionDataContractAttribute.
See the Microsoft .NET Framework documentation for other
supported types.
</ExceptionMessage>
<ExceptionType>
System.Runtime.Serialization.InvalidDataContractException
</ExceptionType>
<StackTrace>
at
System.Runtime.Serialization.DataContract.DataContractCriticalHelper.ThrowInvalidDataContractException(String
message, Type type) at
System.Runtime.Serialization.DataContract.DataContractCriticalHelper.CreateDataContract(Int32
id, RuntimeTypeHandle typeHandle, Type type) at
System.Runtime.Serialization.DataContract.DataContractCriticalHelper.GetDataContractSkipValidation(Int32
id, RuntimeTypeHandle typeHandle, Type type) at
System.Runtime.Serialization.XmlObjectSerializerContext.GetDataContract(Int32
id, RuntimeTypeHandle typeHandle) at
System.Runtime.Serialization.XmlObjectSerializerWriteContext.InternalSerialize(XmlWriterDelegator
xmlWriter, Object obj, Boolean isDeclaredType, Boolean
writeXsiType, Int32 declaredTypeID, RuntimeTypeHandle
declaredTypeHandle) at
WriteArrayOfWeedToXml(XmlWriterDelegator , Object ,
XmlObjectSerializerWriteContext , CollectionDataContract ) at
System.Runtime.Serialization.CollectionDataContract.WriteXmlValue(XmlWriterDelegator
xmlWriter, Object obj, XmlObjectSerializerWriteContext
context) at
System.Runtime.Serialization.XmlObjectSerializerWriteContext.WriteDataContractValue(DataContract
dataContract, XmlWriterDelegator xmlWriter, Object obj,
RuntimeTypeHandle declaredTypeHandle) at
System.Runtime.Serialization.XmlObjectSerializerWriteContext.SerializeAndVerifyType(DataContract
dataContract, XmlWriterDelegator xmlWriter, Object obj,
Boolean verifyKnownType, RuntimeTypeHandle declaredTypeHandle,
Type declaredType) at
System.Runtime.Serialization.XmlObjectSerializerWriteContext.SerializeWithXsiTypeAtTopLevel(DataContract
dataContract, XmlWriterDelegator xmlWriter, Object obj,
RuntimeTypeHandle originalDeclaredTypeHandle, Type graphType)
at
System.Runtime.Serialization.DataContractSerializer.InternalWriteObjectContent(XmlWriterDelegator
writer, Object graph, DataContractResolver
dataContractResolver) at
System.Runtime.Serialization.DataContractSerializer.InternalWriteObject(XmlWriterDelegator
writer, Object graph, DataContractResolver
dataContractResolver) at
System.Runtime.Serialization.XmlObjectSerializer.WriteObjectHandleExceptions(XmlWriterDelegator
writer, Object graph, DataContractResolver
dataContractResolver) at
System.Runtime.Serialization.DataContractSerializer.WriteObject(XmlWriter
writer, Object graph) at
System.Net.Http.Formatting.XmlMediaTypeFormatter.<>c__DisplayClass7.<WriteToStreamAsync>b__6()
at System.Threading.Tasks.TaskHelpers.RunSynchronously(Action
action, CancellationToken token)
</StackTrace>
</InnerException>
</Error>
My subclass of ApiController:
public class WeedAPIController : ApiController
{
//
// GET: /WeedAPI/
public IEnumerable<Weed> GetAllWeeds()
{
return WeedData.GetWeeds();
}
}
My data:
public class WeedData
{
public static Dictionary<string,WeedFamily> GetFamilies(){
return new Dictionary<string,WeedFamily>
{
{"mustard",new WeedFamily("Mustard","Brassicaceae")}
,{"pigweed",new WeedFamily("Pigweed","Amaranthus")}
,{"sunflower",new WeedFamily("Sunflower","Asteraceae")}
};
}
public static List<Weed> GetWeeds(){
var Families = GetFamilies();
return new List<Weed>
{
new Weed("Hairy Bittercress","Cardamine
hirsuta",Families["mustard"])
,new Weed("Little Bittercress","Cardamine
oligosperma",Families["mustard"])
,new Weed("Shepherd's-Purse","Capsella
bursa-pastoris",Families["mustard"])
,new Weed("Wild Mustard","Sinapis arvensis / Brassica
kaber",Families["mustard"])
,new Weed("Wild Radish","Raphanus
raphanistrum",Families["mustard"])
,new Weed("Radish","Raphanus sativus",Families["mustard"])
,new Weed("Redroot Pigweed","Amaranthus
retroflexus",Families["pigweed"])
,new Weed("Prickly Lettuce","Lactuca
serriola",Families["sunflower"])
,new Weed("Spiny Sowthistle","Sonchus
asper",Families["sunflower"])
,new Weed("Annual Sowthistle","Sonchus
oleraceus",Families["sunflower"])
};
}
}