Question

Do you know how I could update an entity in WCF Data Services with OData syntax without the key property of the entity.

For example, an entity:

public class Product
{
    [Key]
    public int Id { get; set; }

    public string Reference { get; set; }
}

I would like to make this request:

PUT myservice.svc/Product('REFXX') 

with ‘REFXXX’ corresponding do the Reference property (which is unique).

Any idea?

Answer 1

I wrote a IDispatchMessageInspector, parse the url and replace the match element in the request parameter with a correct syntax and the real key. I know that the key is not the real “Key” with a specific user agent or with the syntax Service.svc/Entity(SecondaryKey=value), which is used normally for multiple pk’s.

so in the method AfterReceiveRequest the process is:

• parse the url Service.svc/Entity(SecondaryKey=value)
• get the key value of the entity (by building a dynamic linq expression)

• change the match element of the request with Service.svc/Entity(PKValue)

         public object AfterReceiveRequest(ref System.ServiceModel.Channels.Message request, System.ServiceModel.IClientChannel channel, System.ServiceModel.InstanceContext instanceContext)
  {
  
      if (request.Properties.ContainsKey("UriTemplateMatchResults") && HttpContext.Current != null)
      {
          //get match for current request
          UriTemplateMatch match = (UriTemplateMatch)request.Properties["UriTemplateMatchResults"];
  
          Utils.ODataBasicUriParser uriParser = new Utils.ODataBasicUriParser(match.RequestUri.PathAndQuery);
  
          //verify if this is a SecondaryKey request
          if (uriParser.IsEntityQuery && uriParser.IsSecondaryKeyQuery)
          {               
              //TODO this syntax is also used for entities with multiple pk's, test it
  
              //get a new data context
              //TODO see if this can be improved, avoid two datacontext for one request 
              DataContext ctx = new DataContext();
  
              Type outType;
              //get entity type name from the service name 
              string entityName = DataContext.GetEntityNameByServiceName(uriParser.EntityServiceName);
  
              //get the pk for the entity
              string id = ctx.GetEntityId(entityName, uriParser.EntityKey, uriParser.EntityId, out outType);
  
              //verify if the pk has been found or cancel this to continue with standart request process
              if (string.IsNullOrEmpty(id))
              {
                  Trace.TraceWarning(string.Format("Key property not found for the the entity:{0}, with secondaryKeyName:{1} and secondaryKeyValue:{2}",
                      entityName, uriParser.EntityKey, uriParser.EntityId));
  
                  return System.Net.HttpStatusCode.NotFound;
              }
  
              //in odata syntax quotes are required for string values, nothing for numbers
              string quote = outType.FullName == typeof(Int32).FullName || outType.FullName == typeof(Int64).FullName ? string.Empty : "'";
  
              //build the new standart resource uri with the primary key
              var newUri = new Uri(string.Format("{0}/{1}({2}{3}{2})", match.BaseUri.ToString(), uriParser.EntityServiceName, quote, id));
  
              //create a new match to replace in the current request, with the new Uri
              UriTemplateMatch newMatch = NewMatch(match, newUri); 
  
              //set request values
              request.Properties["UriTemplateMatchResults"] = newMatch;
              request.Headers.To = newUri;
              request.Properties.Via = newUri;
          }
      }
  
      return null;
  }
  
  
  UriTemplateMatch NewMatch(UriTemplateMatch match, Uri newUri)
  {
      UriTemplateMatch newMatch = new UriTemplateMatch();
      newMatch.RequestUri = newUri;
      newMatch.Data = match.Data;
      newMatch.BaseUri = match.BaseUri;
  
      return newMatch;
  }
  

works for my current needs