I have a WCF service with cyclic references that I was using the CyclicReferencesAwareAttribute attribute (http://chabster.blogspot.com/2008/02/wcf-cyclic-references-support.html) to solve. However now I want to use the same service with a Silverlight client. Receiving data works well on the Silverlight client with this method, however the CyclicReferencesAwareAttribute attribute does not work on the Silverlight side when I want to send objects back again.
I have changed to use the IsReference property on the data contract which is supposed to get round with this issue. However now the objects that are returned are empty! (All fields are either default or null). This is the same in my ASP.NET client (original) and my Silverlight client.
Has anyone hit is issue before? Here is the attribute.
[System.Runtime.Serialization.DataContract(Namespace="http://testnamespace.co.uk/entities", IsReference=true)]
1- Make sure that all the properties have the System.Runtime.Serialization.DataMember attribute.
2- Make sure that all properties that need to be transfered have a public getter and setter
Related
I am trying to pass an array of custom objects from my asp.net code behind to a webservice method. The webservice is ASMX and I can't change that for now. I can verify up to the point of the code behind calling the webservice, that the custom object is in the array and has the proper values. When I put a break point in the webservice, I notice that the array is null.
I have checked my Service Reference and the collection type is System.array.
I read that I might need to mark my custom class with [DataContract] and the properties as [Datamember] for this to work, but these don't even show up in the intellisense.
I tried all kinds of things and I couldn't get this to work. I tried casting the custom objects as objects and passing them that way. I also tried to cast the whole array as type object and that didn't work. I tried collections; no go. I read a lot on this and couldn't find anyone who could actually do this. So I gave up on doing this with ASMX and tried it with a WCF service. That did work nicely. I created a custom object. I created a strongly typed collection of this class and populated the collection. I then passed this collection to the WCF service and the method was able to see all the objects properly. So if anybody is stuck in the situation I was, try a regular WCF service.
Basically I want to make my script service only serialise properties that are not null on an array of object I am returning... So this..
{"k":"9wjH38dKw823","s":10,"f":null,"l":null,"j":null,"p":null,"z":null,"i":null,"c":null,"m":0,"t":-1,"u":2}
would be
{"k":"9wjH38dKw823","s":10,"m":0,"t":-1,"u":2}
Does anyone know if this is possible?
Basically the reason for this is because null values are for unchanged properties. A local copy is kept in the javascript that is just updated to reduce traffic to the server. Change values are then merged.
You can create a custom JavaScriptConverter class for the JSON serialization process to use to handle your object, and then put the necessary logic in the Serialize method of that class to exclude the properties that are null.
This article has a clear step-by-step discussion of the process involved in creating it.
You probably would not need to actually implement the Deserialize method (can throw a NotImplementedException) if you are not passing that type of object in as an input parameter to your web services.
I am new to the MVC way of programming so please bear with my basic question !
I have a Status class with a default constructor (in an ASP.NET MVC application).
public Status()
{
this.DatePosted = DateTime.Now;
}
I noticed Fluent NHibernate calls this constructor each time it fetched a list of existing Status objects from the database. Hence, the constructor does not seem like the right place to initialize the date.
Where should I move this initialization ? Moving it to the Controller (Add action of Status controller) also seems to violate the principle that the Controller should not make any business decisions. Should I move it to the Status DAO then ? (In traditional ASP.NET Web Form applications I worked with, a DAO simply accepted a business object and saved it to the database and did not contain any logic)
I would like to know the right way to accomplish this. Is there another layer I am missing here where this initialization should take place?
I noticed Fluent NHibernate calls this
constructor each time it fetched a
list of existing Status objects from
the database. This does not seem right
This is exactly what is supposed to be happening. Why wouldn't an ORM call the default constructor for an object? I think every hand rolled DAL and ORM in the world would trigger DatePosted to be reset because thats just how constructors work.
Your DatePosted property should probably set via ModelBinding or manually in the controller and not be part of a constructor.
Enterprise Library Validation Application Block (VAB) integrates with ASP.NET and also with WCF.
Is there a way to integrate ValidationResults created in WCF with ASP.NET?
e.g. an ASP.NET web page invokes a WCF service. The WCF service validates the data using VAB and returns validation information via a FaultContract. The ASP.NET page can take the results and display some error messages. However, a common approach is to indicate which fields have errors (e.g. inline message or asterisk). It seems that most of these approaches will involve being able to correlate the validation result with a control or with a validator.
I don't think there is an out of the box solution but was also curious if anyone had done this and what their approach was.
Since there is no out of the box solution and there aren't any answers posted, I will share what I implemented. I'm not in love with the approach but it is working for me.
Overview
The basic approach is for the ASP.NET page to populate a mapping between properties on the DataContract objects to the ClientId of the control that is being validated. When a validation error occurs the ClientId is returned back from the service to the asp.net page as part of a FaultContract. Then the details from the FaultException are extracted; the ASP.NET page retrieves the ClientId of the control that caused the error and appropriate action can be taken (e.g. change control look and feel or set the text on a validator).
Details
All of the DataContract objects inherit from a base class that exposes a Dictionary. This dictionary is used to map object properties to ASP.NET controls. In the Dictionary, the key is the property name on the DataContract object and the value is the ClientId of the control. Before invoking a service, the client must attach the Dictionary to the DataContract object.
When a ValidationResult is created by Enterprise Library it contains a property called Target which is the object that was validated. ValidationResult also contains a property called key which is the name of the property from the target object that was validated. The ValidationResult key is also a key into the Dictionary that was set in the ASP.NET page before calling the service.
With the ValidationResult key, the ASP.NET supplied information (ClientId) can be extracted from the ValidationResult Target. The information is then added as the Tag of the ValidationResult. Unfortunately, Tag is a readonly property so it has to be set by creating a new ValidationResult and passing the tag to the constructor.
The collection of ValidationResults is then transformed to a pre-existing CustomValidationResults collection (which looks just like ValidationResult) that we needed to use. The CustomValidationResults are then added to a custom ValidationFault and a FaultException is thrown.
The ValidationFaults are then extracted from the FaultException in the ASP.NET page. The ValidationFault contains the ClientId of the control which is associated with the error so the page can choose to display the Messages as it sees fit.
I am using methods with the Attribute [WebMethod] in my aspx pages. I don't use any asp.net ajax but jQuery to call these methods and return objects in JSON. This all works fine.
Next I added an authorization check inside the webMethod, if the current user doesn't have access to the feature I need to let the calling JavaScript know.
So I am throwing an AccessViolationException exception which can then be parsed by the OnError callback function in JavaScript. This works too but the exception includes the full StackTrace and I don't want to make this available to the calling client.
What other ways I could use to return an "Access Denied" to the client when the WebMethod returns a business object?
I'm using ASP.Net 3.5SP1 and jQuery 1.32
You can also add a:
customErrors mode="On"/
in your web.config, this will cut away the stack trace and leave you only the exception message
Why propagate errors through the wire? why not use an error response ?
Just wrap your object in a response object wich can contain an error code for status and an error message to present to users.
As suggested by NunFur I changed my approach and rather than throwing an error, I return a 'richer' object.
There are at least two options, the first one would be to encapsulate my business object into a response object with some status properties. I tried this but it makes the JSON more complicated.
So rather than adding a new object I added two properties to my business object, something like ServiceStatus and ServiceMessage. By default these are 200 and '', but can be set by the WebMethod code if anything goes wrong (no access, proper error). In this case they business object will be 'empty' (no data). The JavaScript code then first checks for the ServiceStatus and reacts appropriately.
I add the two fields to all my objects that are returned by WebMethods, even a simple string. They have to implement an Interface with those two properties.
Now I have complete control over that goes over the wire in case something unexpected is happening.
Thanks for the input
I save exceptions for when things go really wrong. (e.g. can't connect to the database)
Either return nothing (null/nill/whatever), or return a false bool value.
Sorry that I don't have a better answer than that...I'll have to keep looking myself.
You could look at SoapException: http://msdn.microsoft.com/en-us/library/system.web.services.protocols.soapexception(VS.71).aspx
I'm just not sure, if it will work when it is called from JavaScript. Espeially if it's called with a get-request.
BTW AccessViolationException is to my best knowlegde ment to be thrown when the application is accessing memory it has no access to.
/Asger