[ Updated 25 May 2010 ]
I've recently upgraded from VS2008 to VS2010, and at the same time upgraded to .Net 4.
I've recompiled an existing solution of mine and I'm encountering a Cast exception I did not have before.
The structure of the code is simple (although the actual implementation somewhat more complicated).
Basically I have:
public class SomeClass : ISomeClass
{
// Stuff
}
public static class ClassFactory
{
public static IInterface GetClassInstance<IInterface>(Type classType)
{
return (IInterface)Activator.CreateInstance(classType); // This throws a cast exception
}
}
// Call the factory with:
ISomeClass anInstance = ClassFactory.GetClassInstance<ISomeClass>(typeof(SomeClass));
Ignore the 'sensibleness' of the above - its provides just a representation of the issue rather than the specifics of what I'm doing (e.g. constructor parameters have been removed).
The marked line throws the exception:
Unable to cast object of type
'Namespace.SomeClass' to type
'Namespace.ISomeClass'.
I suspect it may have something to do with the additional DotNet security (and in particular, explicit loading of assemblies, as this is something my app does).
The reason I suspect this is that I have had to add to the config file the setting:
<runtime>
<loadFromRemoteSources enabled="true" />
</runtime>
.. but I'm unsure if this is related.
Update
I see (from comments) that my basic code does not reproduce the issue by itself. Not surprising I suppose. It's going to be tricky to identify which part of a largish 3-tier CQS system is relevant to this problem.
One issue might be that there are multiple assemblies involved. My static class is actually a factory provider, and the 'SomeClass' is a class factory (relevant in that the factories are 'registered' within the app via explicit assembly/type loading - see below) .
Upfront I use reflection to 'register' all factories (i.e. classes that implement a particular interface) and that I do this when the app starts by identifying the relevant assemblies, loading them and adding them to a cache using (in essence):
Loop over (file in files)
{
Assembly assembly = Assembly.LoadFile(file);
baseAssemblyList.Add(assembly);
}
Then I cache the available types in these assemblies with:
foreach (Assembly assembly in _loadedAssemblyList)
{
Type[] assemblyTypes = assembly.GetTypes();
_loadedTypesCache.AddRange(assemblyTypes);
}
And then I use this cache to do a variety of reflection operations, including 'registering' of factories, which involves looping through all loaded (cached) types and finding those that implement the (base) Factory interface.
I've experienced what may be a similar problem in the past (.Net 3.5, so not exactly the same) with an architecture that involved dynamically creating classes on the server and streaming the compiled binary of those classes to the client app. The problem came when trying to deserialize an instance of the dynamic class on the client from a remote call: the exception said the class type was not know, even though the source and destination types were exactly the same name (including namespace). Basically the cross boundry versions of the class were not recognised as being the same. I solved that by intercepting the deserialization process and explicitly defining the deseriazation class type in the context of the local assemblies.
This experience is what makes me think the types are considered mismatched because (somehow) the interface of the actual SomeClass object, and the interface of passed into the Generic method are not considered the same type.
So (possibly) my question for those more knowledgable about C#/DotNet is: How does the class loading work that somehow my app thinks there are two versions/types of the interface type and how can I fix that (keeping in mind its a DotNet 3.5 vs 4 issue as it worked before my upgrade) ?
[ whew ... anyone who got here is quite patient .. thanks ]
I would say yes that it has something to do either with the runtime loading of assemblies, or with the upgrade conversion, I used this code in a new project and had no issues. Can you provide more code to replicate the error?
The 'quick' (ITO implementation, not ITO finding it) solution was to stop the shadow copy of my app's DLLs.
This is done by modifying the ASP.Net app's Web.Config file as follows:
In section 'configuration/web.settings', add setting:
<hostingEnvironment shadowCopyBinAssemblies="false" />
Related
I have inherited a WCF RIA, Silverlight 4 application that has been dormant for a few years. It is assumed that the code is stable. To get it working I need to install dependencies which were not documented, as far as I can tell.
After installing dependencies based on what information I could gather I am left with the following error.
Operation named 'namereplaced' does not conform to the required
signature. Parameter types must be an entity type or one of the
predefined serializable types
I already tried uninstalling Ria Services as recommended here.
WCF Ria Operation does not conform to the required signature
but this leads to more errors.
I've also tried hunting down a specific version of the Ria Services Toolkit as suggest here, but no luck
https://social.msdn.microsoft.com/Forums/silverlight/en-US/86f40859-18e8-4ce6-8d8a-a864fbe4e3ac/error-operation-named-createuser-does-not-conform-to-the-required-signature-parameter-types?forum=silverlightwcf
Additionally, I tried setting up a drop retrieved from the client's FTP in IIS and saw the following in the machine Event Log
: The service
'/AppName/Services/SomeManager-Web-Services-ImportService.svc' cannot
be activated due to an exception during compilation. The exception
message is: Operation named 'namereplaced' does not conform to the
required signature. Parameter types must be an entity or complex type,
a collection of complex types, or one of the predefined serializable
types.. ---> System.InvalidOperationException: Operation named
'namereplaced' does not conform to the required signature. Parameter
types must be an entity or complex type, a collection of complex
types, or one of the predefined serializable types.
However, using an old installer that the IT team found in the old developers files, I was able to set up an instance of the website which does not generate these errors, but is incompatible with the latest version of the database. I haven't found the source for the setup project in source control.
The method in question is defined as follows
[Invoke(HasSideEffects=true)]
public void NameReplaced(IEnumerable<ImportRecord> recs)
{
foreach (var item in recs)
{
UpdateImportRecord(item);
}
}
I'd ideally like to resolve this without trying to change the code as an investigation needs to be done on an error in the clients environment, then further updates are required.
EDIT:
Included suggestion from Mark W,
public IQueryable<ImportRecord> GetImportRecords()
{
return null;
}
but the same build error is reported.
Since this project is being resurrected for some purpose, I recommend that you use the latest Visual Studio and move it to Silverlight 5. The thought is why deal with old technology which will frankly hamper the process.
Comment out the things that don't work to until you have a running (not operational though) baseline to start from. Then bring back in the things which are causing problems.
I say this from having worked extensively in both S4 & S5 and frankly (to the code) not much changed; in doing this process, yes the upgrade will have problems but they are not insurmountable. Plus the installs smarts got better for S5 and later versions of Visual Studio.
We run RIA Services on a server that does not have it installed. What we did was publish the web site with Copy Local = true on:
System.ServiceModel.DomainServices.EntityFramework
System.ServiceModel.DomainServices.Hosting
System.ServiceModel.DomainServices.Hosting.OData
System.ServiceModel.DomainServices.Server
If that is not it - Due to the magic of domain services, the service needs to auto-generate the class type. Only types that are returned from the service are generated. If the domain service does not have a method to return an Iqueryable or Ienumerable of type ImportRecord, you can create a method that returns null - that will be enough for the code to generate.
Those are my 2 first thoughts.
EDIT: This looks like what I'm talking about :previously asked question
I am currently building an emulator in C#/Silverlight. Because we are emulating a particular software domain, we have domain-level classes (Cube, CubeSet, BaseApp, etc.) that we have to implement within the scope of our emulator. Additionally, these domain-level classes have to be available to the application developer because they are accessible to applications which will be emulated.
So what we have is a .dll which is a compilation of just the domain-level classes, and then within the emulator implementation itself we have a package of the same domain-level classes.
The goal is to dynamically instantiate the application object, which is doable, and then call a sequence of that application's methods to carry out the emulation. However, in calling one of the methods, we have to pass in a domain-level object which is instantiated within the emulator implementation. We have to call AssociateCubes (which takes a CubeSet parameter) on the dynamically instantiated application. When I try to do that dynamically, I'm getting an InvalidCastException which (amusingly enough) says that a "CubeSet" object cannot be cast as a "CubeSet" object. An example of the code being used to dynamically access the application is:
Object o = Activator.CreateInstance(appType);
MethodInfo AssocCubes = o.GetType().GetMethod("AssociateCubes");
AssocCubes.Invoke(o, new object[] { Cubes });
where Cubes is of type CubeSet in the emulator, and the appType is as given by the user.
Is there any way to force some sort of link between the two so that the compiler recognizes that in reality the same class, or is it that the two classes are completely distinct and cannot be associated in such a way to allow an object of one type to be cast as the other.
One solution I have considered is simply defining a method to manually copy the contents of one object to an instance in the emulator, but the problem therein is that the application developer can define their own methods for the application class to be used as helper methods.
I may not have explained everything completely, so I can offer any clarifications that may help expose a potential solution.
The InvalidCastException only shows last portion of full class name for convinience, but types are compared on full identity: Full Name (including namespaces) and assembly it is coming from (which may have strong name if signed).
Consider using Unit Testing framework for "mocking" objects. Or at least read on how such frameworks wrap classes.
The real fix is to use testable class hierarchies. Often using interfaces instaed of concreate classes help to solve this type if issues.
I don't want to discount the previous answer given, but I have found a solution as I described in the comment I wrote.
What I do instead is pull the domain layer out of the emulator project and compile it separately as a DLL. Now that DLL is referenced in the emulator and the separate applications, so when the types are loaded dynamically they are considered to be the same type after all.
I created a new unit test project to test my NHibernate mappings.
The NHibernate mappings are in a project that also contains EF entities.
In my unit test I only use types that don't even have an indirect reference to the Entity Framework, but still, when I compile the unit test project, I get the following error:
The type 'System.Data.Objects.DataClasses.IEntityWithRelationships' is defined in an assembly that is not referenced. You must add a reference to assembly 'System.Data.Entity, Version=3.5.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'.
Is there any way to find out, why this reference is needed? I already checked all used classes multiple times and couldn't find anything...
I have the feeling I am missing something here...
You could use a DLL inspection tool (like JustDecompile (freee!), or Reflector) and have a look inside your test-referenced DLLs. You'll spot the one with the Using statement quite quickly, hopefully, and get a clearer picture of what's happening.
As has been said, double-clicking will pull up the error location but only if it's in code you've written, third party DLLs naturally won't play ball.
Good luck :)
You are sure that you don't use types inheriting or implementing any of the types in System.Data.Entity, this could be buried deep in the inheritance chain, like the use of a method returning a object defined in your DAL which either directly implements IEntityWithRelationships or gets the implementation from a base class also defined in your DAL, that would conceal the use of System.Data.Entity from your test assembly when you try to find references as it would show up as being used by an entity in your DAL instead... (Depending on what feature you are using to determine this, I am just guessing something like "Find Usages")
E.g. in your A, B, C example... if say A uses a B3 class that inherits from C2. When searching for usages on C2 you would only find B3 and not A. But because A uses B3 which inherits C2, A requires a reference to C
I would check out Pistachio. It is made to load in a .csproj, then find all the resources in the project and where they are used. Might be worth a shot to find out where that DLL is needed.
You can use http://checkasm.booring.net/ CheckAsm tool. Load all your assemblies that you refer directly in your project and find out which one is using the missing reference. From there you need to ask the provider of that reference why they needed that assembly.
Hope that would help.
The only thing I can think of is... Since you're using NHibernate and EF, I'm guessing your doing some type of POCO implementation. I've seen some stuff on the web about implementing POCO with NHibernate and EF where the base classes you define implement the IEntityWithRelationships interface. If that's the case it would explain it.
You are referencing a library which has a public method or property that either returns a 'System.Data.Objects.DataClasses.IEntityWithRelationships' or takes one as a parameter. Regardless of it you are actually using the method, because it is public your code has to be able to determine the method signatures of all of the methods in the library you're referencing. If the method was internal you wouldn't see the issue.
I assume you tried just double clicking on the error? That will usually go to the actual point of using the unknown type(either a return value/property or inheritance/implementation).
If that didn't work then it must be in compiler magic code(possibly for EF as people have pointed out, or somewhere else). In that case my suggestion would be to add the reference to your test assembly. Then open it in Reflector and look through the compiled MSIL. Since it is giving you a specific interface you could even just go to that interface and ask Reflector for where it is referenced to see where it is in your assembly.
Could it be that one of your classes has the same name as a EF-class? Then it might be VS that is generating Code to apply the interface IEntityWithRelationships to your class to simulate POCO mapping of the classes.
To use POCO entities with a data model, the name of the entity type must be the same as the custom data class, and each property of the entity type must map to a public property of the custom data class. The names of the types and each of the mapped properties must be equivalent.
Source: http://msdn.microsoft.com/en-us/library/dd456853.aspx
It might be unrelated, but I had similar errors a while ago, I cleared out the ASP.NET assembly cache folder and it fixed my problem.
the folder is here
{windows folder}\Microsoft.NET\Framework\v4.0.30319\Temporary ASP.NET Files
and it was holding an old version of my assembly
Is there any way to save an entire class definition for a C# object to a file / data store?
I use the [Serializable] tag and ISerializable interface to do this already, but both of these rely on the object definition being in the assembly at run time.
What I'm looking for is a solution to the following scenario:
1) User creates object MyClass in my software and saves it
For the purpose of this example, MyClass is a stand-alone object that doesn't rely on any other class in the system:
i.e. this could be the entire definition:
public class MyClass
{
public int MyProperty { get; set; }
public void DoSomething() { /* do something, like Console.Write(""); */ }
}
2) We release a patch that removes MyClass from the system
3) User loads the saved MyClass from step 1 and calls DoSomething() on it - and has the function work exactly the same as it did before the patch removed the class from the system
Is there any way this can be done without reflection / emit trickery?
No, this won't work without emitting the type definition. What you are trying to do is actually save off the code (otherwise, how would DoSomething work?) - which is what the compiler does for you. Plain serialization will never work for you here.
So, if you need to save behavior as well as state, you need to either keep the historical code around, use some type of reflection emit trickery to persist the type definition as a loadable assembly, or use dynamic programming tricks that treat data as executable code.
When I have had do versioned serialization before, I normally have custom serialization logic and a "version" attribute on the object - using this I can create a type that I've moved and renamed - say SomeClass to Archive.SomeClassV3. You can use Version Tolerant Serialization for this, but I prefer to implement ISerializable and use serialization proxies if this is required. (Well, actually I prefer to avoid this problem altogether!)
Well, you could keep all of these serializable classes in their own DLLs, package the DLLs with the application, and have the DLLs loaded at runtime. That way, even if you remove the classes from the latest version of the application, the loaded DLLs will still work.
This seems like a scary approach, though ... now you have clients running ancient code that you no longer even have in your source control repository. How are you supposed to debug that?
You talking about not class-property serialization, but about process-serialization (or method-, doesn't matter). But unlike property serialization, this should contain MSIL-code that runs when you need it. So you must somehow translate it to a bin-code and then run by Assembly.Load, for example. I guess this is not an easy way to do this. So, if this is possible - store your implementation of MyClass to a separate dll, or as a string (in c# language) for further compilation and execution by reflection.
Due to politics at the very large finanial institution for which I work, I am not able to use Castle Project's ActiveRecord implementation, but like the pattern so much I have implemented it myself. This is complete, and now management is looking for a GUI tool to browse all the activerecord classes, search for instances and manage data.
To this end, I'm building a "browser" that iterates through all the classes in a referenced project, and if they are derived from a partiular base class ("ActiveInstanceBase"), make them available for inspection and modification in an ASP.net datagrid.
The first step for me is to figure out how to iterate through all the references in the current project (developers using this tool will add their dlls to the project as references) and identify the ActiveInstance classes in order to fill a dropdown full of types to inspect.
How do I get a list of all the references for a current project? Google is not turning anything up for me on the first page of results for a number of queries. I'm getting a lot of stuff about writing Visual Studio addins, but nothing for runtime inspection.
How do I determine the base class of a derived type at runtime if the base class takes a Type parameter?
if (t.IsSubclassOf(typeof(ActiveInstance.ActiveInstanceBase)))
{}
Isn't the proper syntax, and I can't know t at runtime.
I'm also forced to use IE6, so pardon if this post is not very well-formatted. Thanks very much in advance!
1) How to get the assemblies referenced in your project
Assembly ourAssembly = Assembly.GetEntryAssembly();
AssemblyName[] refs = ourAssembly.GetReferencedAssemblies();
2) Use Type.IsSubclassOf() or Type.GetInterface()
Type theType = typeof(ActiveInstance.ActiveInstanceBase<>);
foreach(Type type in assembly.GetTypes())
{
if (type.IsSubclassOf(theType))
{ ... }
}
Those should work for you...
if you have political rules against downloading third party software, this may not work, but I use .net Reflector. It will give you the references and decompile the code for reviewing.
http://www.red-gate.com/products/reflector/