I'm trying to configure the SignalR JSon serializer to handle reference loops in my objects graph.
I have seen similar questions on SO, and borrowed the code below from there.
Following is the relevant part of the ConfigureServices method:
services.AddSignalR().AddJsonProtocol(options =>
{
options.PayloadSerializerSettings.PreserveReferencesHandling = PreserveReferencesHandling.Objects;
options.PayloadSerializerSettings.ReferenceLoopHandling = ReferenceLoopHandling.Serialize;
});
Unfortunately, even with this configuration, trying to send data on the wire throws the following exception:
Self referencing loop detected for property 'Vehicule' with type 'A.B.C.Vehicle'. Path ...
Obviously this code is not enough, but I can't figure out what to do.
Any help appreciated.
Add ShouldSerializePROPERTYNAME entry to your model source file:
public bool ShouldSerializeVehicule()
{
return false;
}
or apply the attribute [JsonIgnore] to Vehicule.
This tells Json to skip it.
Related
I have server side code written which is including navigational property for many to many relation ship as shown below.
var result = _contextProvider.Context.ResourceProperty.Include("AssociatedStandardResourceProperty.AssociatedLists").Where(t => t.ResourceId == resId);
//Return matching resource properties
return result;
However, when i am trying to retrieve data from breeze datacontext i am getting query execution error as shown below.
var getResourceProperties = function (resourceId, resourcePropertyObservable) {
var query = EntityQuery.from('GetResourceProperties')
.withParameters({ resourceId: resourceId })
.expand("AssociatedStandardResourceProperty.AssociatedLists");
return manager.executeQuery(query)
.then(querySucceeded)
.fail(queryFailed);
function querySucceeded(data) {
if (resourcePropertyObservable) {
resourcePropertyObservable(data.results);
}
log('Retrieved listObservable from remote data source',
data, true);
}
};
Query is failing and all data is retreived in log message i have written in queryFailed function.
I have also checked by removing expand at client side and also removing include at server side and then including expand at client side.
Please let me know how i can make it work.
Thanks
I have observed that problem was due to many to many mapping between two entities . After removing the relationship we are able to retrieve associatedEntities data
Just a guess here, but if you are performing the include on the server, then you don't need the expand on the client and vice versa. Your example seems to be doing both. What is the error message that you are getting?
I was using Breeze v1.1.2 that came with the Hot Towel template which has now been extended to form my project. I made the mistake of updating the NuGet package to the current 1.3.3 (I never learn). Anyway, all was well, and now not so much!
I followed the instructions in the release notes and other docs to change my BreezeWebApiConfig file to:
[assembly: WebActivator.PreApplicationStartMethod(
typeof(BreezeWebApiConfig), "RegisterBreezePreStart")]
namespace MyApp.App_Start {
public static class BreezeWebApiConfig {
public static void RegisterBreezePreStart() {
GlobalConfiguration.Configuration.Routes.MapHttpRoute(
name: "BreezeApi",
routeTemplate: "breeze/{controller}/{action}"
);}}}
And the config.js file (which provides the serviceName to the EntityManager constructor) to:
var remoteServiceName = 'breeze/breeze'; // NEW version
//var remoteServiceName = 'api/breeze'; // OLD version
And my BreezeController if you're interested:
[BreezeController]
public class BreezeController : ApiController
{
readonly EFContextProvider<MyDbContext> _contextProvider =
new EFContextProvider<MyDbContext>();
[HttpGet]
public string Metadata()
{
return _contextProvider.Metadata();
}
[HttpGet]
public IQueryable<SomeItem> SomeItems()
{
// Do stuff here...
}
}
Now I get the "cannot execute _executeQueryCore until metadataStore is populated" error.
What am I missing here?
EDIT:
I perhaps left out the part you needed... Above in the SomeItems() method, the stuff that actually gets done is a call to the GetMeSomeData() method in the MyDBContext class. This method makes the following call to a stored procedure to get the data.
public virtual ObjectResult<SomeItem> GetMeSomeData(string inParam)
{
var p = new object[] { new SqlParameter("#inParam", inParam) };
var retVal = ((IObjectContextAdapter)this).ObjectContext.ExecuteStoreQuery<SomeItem>("exec GetData #SN", p);
return retVal;
}
Now given my limited understanding, the call to Metadata() is not failing, but I don't think it has any idea what the entity model is when coming back, even though somewhere along the line, it should figure that out from the entity model I do have (i.e. SomeItem)? The return string from Metadata() doesn't have any information about the entity. Is there a way to make it aware? Or am I just completely off in left field playing with the daisies?
Hard to say based on this report. Let's see if Breeze is right.
Open the browser debugging tools and look at the network traffic. Do you see an attempt to get metadata from the server before you get that error? If so, did it succeed? Or 404? Or 500? What was the error?
I'm betting it didn't even try. If it didn't, the usual reason is that you tried some Breeze operation before your first query ... and you didn't ask for metadata explicitly either. Did you try to create an entity? That requires metadata.
The point is, you've got to track down the Breeze operation that precipitates the error. Sure everything should just work. The world should be rainbows and unicorns. When it isn't, we heave a sigh, break out the debugger, and start with the information that the error gave us.
And for the rest of you out there ... upgrading to a new Breeze version is a good thing.
Happy coding everyone.
Follow-up to your update
Breeze doesn't know how you get your data on the back-end. If the query result has a recognizable entity in it, Breeze will cache that. It's still up to you in the query callback to ensure that what you deliver to the caller is something meaningful.
You say that you're server-side metadata method doesn't have any idea what SomeItem is? Then it's not much use to the client. If it returns a null string, Breeze may treat that as "no metadata at all" in which case you should be getting the "cannot execute _executeQueryCore until metadataStore is populated" error message. Btw, did you check the network traffic to determine what your server actually returned in response to the metadata request (or if there was such a request)?
There are many ways to create Metadata on the server. The easiest is to use EF ... at least as a modeling tool at design time. What's in that MyDbContext of yours? Why isn't SomeItem in there?
You also can create metadata on the client if you don't want to generate it from the server. You do have to tell the Breeze client that you've made that choice. Much of this is explained in the documentation "Metadata Format".
I get the feeling that you're kind of winging it. You want to stray from the happy path ... and that's cool. But most of us need to learn to walk before we run.
I am working with a database first model in Entity Framework 5 and when I attempt to add a row, I get the following error:
"No views were found in assemblies or could be generated for Table 'ui_renewals'."
The table exists in my EDMX and the template generated a ui_renewals class. I've deleted the table from the EDMX and added it again using the Update Model from Database option and I get the same error. Creating a separate connection for it resolves the issue, but that seems like a less-than-ideal solution (more like a kludge) not to mention it makes it more difficult to maintain in the future.
Any ideas on how to fix this so that I can add or update (I've tried both) a row in ui_renewals?
Here is the code I'm currently using - only difference before was using db as a DBContext instead of ui (yes, receipt is misspelled - gotta love legacy stuff)
[HttpPost]
public bool UpdateTeacher(string login_id, string password, UIRenewal data)
{
if (ModelState.IsValid)
{
// map from UIRenewal VM to ui_renewal
ui_renewals Renewal = Mapper.Map<UIRenewal, ui_renewals>(data);
// check to see if this is a new entry or not
var tmp = ui.ui_renewals.Find(Renewal.reciept);
if (tmp == null)
ui.ui_renewals.Add(Renewal);
else
{
// mark as modified
db.Entry(Renewal).State = EntityState.Modified;
}
// save it
try
{
ui.SaveChanges();
}
catch (DBConcurrencyException)
{
return false;
}
return true;
}
return false;
}
I should mention that I do have a view in the model (v_recent_license).
I know this is a very old question, however as I haven't found any other topics like this, I'll post my answer.
I have had the same Exception thrown. I found that, in a failed attempt to optimize EF performance, following the advices found here, I left behind this piece of code in EF .edmx code-behind:
<EntityContainerMapping StorageEntityContainer="XXXModelStoreContainer" CdmEntityContainer="YYYEntities" GenerateUpdateViews="false">
I removed the GenerateUpdateViews="false" string, and all is working again.
(The Exception message is a little misleading in my opinion).
I've created an app using MVVMCross, the IOS and Android versions are working but when I tried to "port" to WP7 and I ran into the following problem:
throw methodAccessException.MvxWrap("Problem accessing object - most likely this is caused by an anonymous object being generated as Internal - please see http://stackoverflow.com/questions/8273399/anonymous-types-and-get-accessors-on-wp7-1");
As mentioned in the answer to my other question about this (on Android) you have to set an InternalsVisibleTo attribute in the AssemblyInfo.cs for WP7. So I did:
[assembly: InternalsVisibleTo("Cirrious.MvvmCross.WindowsPhone")]
But this doesn't make any difference. I use the following code to send two variables form my BeckhoffViewModel to my BeckhoffSensorViewModel.
BeckhoffViewModel:
public IMvxCommand BeckhoffSensor1
{
get
{
return new MvxRelayCommand(kvpSens1);
}
}
private void kvpSens1()
{
RequestNavigate<BeckhoffSensorViewModel>(new { VarType = "short", Variable = ".countertest" });
}
BeckhoffSensorViewModel:
public BeckhoffSensorViewModel(string VarType, string Variable)
{
_vartype = VarType;
_variable = Variable;
}
Anything I'm overlooking? I also looked at the other stackoverflow topic mentioned in the exception but couldn't really understand it.
The anonymous class will most definitely be created as internal by the compiler - which is why you need the line [assembly: InternalsVisibleTo("Cirrious.MvvmCross.WindowsPhone")]
Can you check that the AssemblyInfo.cs file definitely being linked into the project (and that this is the project containing the ViewModel/anonymous-class code)?
If that is the case, can you check the methodAccessException to see what the message is?
If that doesn't help, can you use a tool like Reflector to check the internalVisible attribute is actually present on the core/application assembly?
I have entities that I am getting via Entity Framework. I'm using Code-First so they're POCOs. When I try to XML Serialize them using XmlSerializer, I get the following error:
The type
System.Data.Entity.DynamicProxies.Song_C59F4614EED1B7373D79AAB4E7263036C9CF6543274A9D62A9D8494FB01F2127
was not expected. Use the XmlInclude
or SoapInclude attribute to specify
types that are not known statically.
Anybody got any ideas on how to get around this (short of creating a whole new object)?
Just saying POCO doesn't really help (especially in this case since it looks like you're using proxies). Proxies come in handy in a lot of cases but make things like serialization more difficult since the actual object being serialized is not really your object but an instance of a proxy.
This blog post should give you your answer.
http://blogs.msdn.com/b/adonet/archive/2010/01/05/poco-proxies-part-2-serializing-poco-proxies.aspx
Sorry, I know I'm coming at this a bit late (a couple YEARS late), but if you don't need the proxy objects for lazy loading, you can do this:
Configuration.ProxyCreationEnabled = false;
in your Context. Worked like a charm for me. Shiv Kumar actually gives better insight into why, but this at least will get you back to work (again, assuming you don't need the proxies).
Another way that works independent of the database configuration is by doing a deep clone of your object(s).
I use Automapper (https://www.nuget.org/packages/AutoMapper/) for this in my code-first EF project. Here is some sample code that exports a list of an EF objects called 'IonPair':
public bool ExportIonPairs(List<IonPair> ionPairList, string filePath)
{
Mapper.CreateMap<IonPair, IonPair>(); //creates the mapping
var clonedList = Mapper.Map<List<IonPair>>(ionPairList); // deep-clones the list. EF's 'DynamicProxies' are automatically ignored.
var ionPairCollection = new IonPairCollection { IonPairs = clonedList };
var serializer = new XmlSerializer(typeof(IonPairCollection));
try
{
using (var writer = new StreamWriter(filePath))
{
serializer.Serialize(writer, ionPairCollection);
}
}
catch (Exception exception)
{
string message = string.Format(
"Trying to export to the file '{0}' but there was an error. Details: {1}",
filePath, exception.Message);
throw new IOException(message, exception);
}
return true;
}