WCF RIA Services - Passing a custom object to a query method as parameter

Question

I want to pass a custom class as parameter to the query method which returns me a collection of entities. I need something like this

[Query]
public IEnumerable<MyEntity> Search(SearchParams params)
{
 //do something here
}

public class SearchParams
{
  public string FilterParam1 {get; set;}
  public string FilterParam2 {get; set;}
  public string FilterParam3 {get; set;}
  public string FilterParam4 {get; set;}
  public string FilterParam5 {get; set;}
...and so on...
}

I tried making SearchParams class available at client side using shared code. But the problem is that no operation(query or invoke) let me create a method where I can pass SearchParams class as it is not a native serializable type. I have about 15 properties in SearchParams class like this.

I do not want to create a Query operation with 15 parameters. Please suggest is there's a good workaround for that.

Answer 1

If you are prepared to sacrifice change tracking etc on the returned entities then you could use an 'Invoke' method instead. This will allow you to pass complex types as parameters (as long as they are exposed to the client).

You can expose the type by writing a dummy query method that returns your complex type.

See this other question for more details.

As far as I am aware, the abilitiy to pass complex types as parameters to 'Query' methods is on the roadmap but not currently available.

Answer 2

I think you missed the whole point with the Query method :-)

The Load method which you use to "execute" the query method takes a Query as an argument. Use that one instead of using your own "query object".

For example something like this:

EntityQuery<YourEntity> query = from e in dx.GetYourEntityQuery()
                                where e.Foo == "something"
                                select e;

dx.Load<YourEntity>(query);

Answer 3

As Frederick said, one of the main points of RIASvcs is you can send a custom query (LINQ expression) over the wire from the client, to the server, and have it executed there.

It brings all the records to the web server and then filters them.

If I understand you correctly, this isn't true-- bring up Fiddler and see what gets sent back-and-forth, it is indeed filtering on the server and only returning (to the client) what was asked for.

Answer 4

If you read what Martin Fowler says about SOA: When you're working with a remote interface, such as Remote Facade (388), each call to it is expensive. As a result you need to reduce the number of calls, and that means that you need to transfer more data with each call So your question has only one answer, yes. It doesn't make sense to expose complex type like Expression or Func through WCF just because you want to provide a simple syntax in the client. You have the DataContract, use that to expose a Dto that represent your query.