REST with nullable types?

Question

I've hit a brickwall. My REST implementation won't accept Nullable values.

    [OperationContract]
    [WebInvoke(ResponseFormat = WebMessageFormat.Json, UriTemplate = "/Transactions?AccNo={AccNo}&CostCentreNo={CostCentreNo}&TransactionType={TransactionType}&Outstanding={Outstanding}&CheckStartDate={CheckStartDate}&CheckEndDate={CheckEndDate}")]
    List<Transactions> GetTransactions(Int32 AccNo, Int32 CostCentreNo, Int32 TransactionType, Boolean Outstanding, DateTime? CheckStartDate, DateTime? CheckEndDate);

Whereas my original SOAP implementation does. So is there a way around this? Or do I have to re-write my code?

I still don't quite get why a datetime must be nullable anyway to be set to null.

Answer 1

Variables for UriTemplate query values must have types that can be converted by QueryStringConverter. Nullable types is not.

You could wrap the parameters and pass it through POST as such;

[DataContract(Name = "Details", Namespace = "")]
public class Details
{
    [DataMember]
    public Int32 AccNo;
    [DataMember]
    public Int32 CostCentreNo;
    [DataMember]
    public Int32 TransactionType;
    [DataMember]
    public Boolean Outstanding;
    [DataMember]
    public DateTime? CheckStartDate;
    [DataMember]
    public DateTime? CheckEndDate;

    public Details()
    {}
}

[OperationContract]
[WebInvoke(Method = "POST", UriTemplate = "/Transactions",
     RequestFormat = WebMessageFormat.Json,
     ResponseFormat = WebMessageFormat.Json,
     BodyStyle = WebMessageBodyStyle.Bare)]
List<Transactions> GetTransactions(Details details);

Opionally, you could pass the date as strings instead of DateTime, and then use DateTime.Parse() on the string on the receiving end.