Devart Forums

Here is my scenario:

I have built a WCF Data (oData) service that is using dotConnect for Ora provider, version 5.70.190.0. When I execute a query to a single entity, selecting up to 8 properties, all is well. However, if I add just one more property/column to the list of selects I get the following exception (the type of the newly added property does not seem to make any difference) :

ArgumentNullException: Value cannot be null.Parameter name: value

and here is the stack trace:

at System.Data.Services.WebUtil.CheckArgumentNull[T](T value, String parameterName)
at System.Data.Services.Internal.ProjectedWrapper.set_PropertyNameList(String value)
at lambda_method(Closure , Shaper )
at System.Data.Common.Internal.Materialization.Coordinator`1.ReadNextElement(Shaper shaper)
at System.Data.Common.Internal.Materialization.Shaper`1.SimpleEnumerator.MoveNext()
at System.Data.Services.Internal.ProjectedWrapper.EnumeratorWrapper.MoveNext()
at System.Data.Services.DataService`1.SerializeResponseBody(RequestDescription description, IDataService dataService)
at System.Data.Services.DataService`1.HandleNonBatchRequest(RequestDescription description)
at System.Data.Services.DataService`1.HandleRequest()

I saw forums that mention similar problems, but it was recommended that the users upgrade and I am already using the latest version of the dotConnect for Ora.

Does anyone have any idea where I need to look at?
Is this a known issue?

It appears that the length of the URL is in play here - if I have it under around 180 characters it works, if it is higher than that, not so much.

Many thanks in advance, G.

I have sent you a test OData solution to the e-mail you have provided in your profile.

Thanks Andrey!

I am not sure when you did send the email but I have not received anything yet. Could you please resend?

I have sent the sample once again. The first one was blocked by your mail server because of the .js files.

Thanks Andrey!

I have sent a sample solution to [email protected] that clearly illustrates the issue. Please review and advise.

G.

Thank you for the report, we have reproduced the error.
We will let you know about the results of our investigation.

Unfortunately, this is designed behaviour.
We are unable to change OData projection rules.

Please put the following line in the constructor of your context (the Devart.Data.Oracle.Entity.OracleEntityProviderServices class is defined in the %ProgramFiles%\Devart\dotConnect\Oracle\Entity\EF4\Devart.Data.Oracle.Entity.dll assembly): Refer to http://blogs.planetsoftware.com.au/paul ... d-wcf.aspx . This is actually the problem of WCF Data Services which doesn't take into account the peculiarities of other RDMS (Oracle treats empty strings in varchar columns as null).

This problem was solved in WCF Data Service 5.0.2: "Fixes a bug where projections involving more than eight columns would fail if the EF Oracle provider was being used" (http://blogs.msdn.com/b/astoriateam/arc ... eased.aspx)

No workaround from provider's side is needed now.