We Keep Coding

Using reflection to instantiate a class from an external assembly

I am currently trying to develop a method of running test classes in external projects programmatically using reflection. Here is a simplified chunk of code that should showcase my problem.
string pathToDLL = #"C:\Path\To\Test\Project\UnitTests.dll";
IEnumerable<Type> testClasses = assembly.GetExportedTypes();
Type testClass = testClasses.First();
object testClassInstance = assembly.CreateInstance(testClass.FullName);
This code throws the following exception:
'assembly.CreateInstance(testClass.FullName)' threw an exception of type 'System.Reflection.TargetInvocationException'
Data: {System.Collections.ListDictionaryInternal}
HResult: -2146232828
HelpLink: null
InnerException: {System.IO.FileNotFoundException: Could not load file or assembly 'Project.Core, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null'. The system cannot find the file specified.
File name: 'Project.Core, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null'
at Project.UnitTests.TestClass..ctor()}
Message: "Exception has been thrown by the target of an invocation."
Source: "System.Private.CoreLib"
StackTrace: " at System.RuntimeTypeHandle.CreateInstance(RuntimeType type, Boolean publicOnly, Boolean noCheck, Boolean& canBeCached, RuntimeMethodHandleInternal& ctor, Boolean& bNeedSecurityCheck)\r\n at System.RuntimeType.CreateInstanceSlow(Boolean publicOnly, Boolean skipCheckThis, Boolean fillCache, StackCrawlMark& stackMark)\r\n at System.Activator.CreateInstance(Type type, Boolean nonPublic)\r\n at System.RuntimeType.CreateInstanceImpl(BindingFlags bindingAttr, Binder binder, Object[] args, CultureInfo culture, Object[] activationAttributes, StackCrawlMark& stackMark)\r\n at System.Activator.CreateInstance(Type type, BindingFlags bindingAttr, Binder binder, Object[] args, CultureInfo culture, Object[] activationAttributes)\r\n at System.Reflection.Assembly.CreateInstance(String typeName, Boolean ignoreCase, BindingFlags bindingAttr, Binder binder, Object[] args, CultureInfo culture, Object[] activationAttributes)\r\n at System.Reflection.Assembly.CreateInstance(String typeName)"
In the stack trace it states that it "Could not load file or assembly 'Project.Core...'".
This project is one that the target DLL references directly (one that it tests). Does anyone know why this won't be able to pick up these DLLs automatically?
I've investigated ways of solving this problem:
It could be the way that the dlls have been compiled - this can be changed as I am in control of this - which is currently by running dotnet build */*/project.json at solution level. This successfully compiles everything, and all of the relevant DLLs seem to be populated in the bin folder. I've also investigated whether or not changing to dotnet publish or dotnet build */*/project.json --configuration Release though neither seem to have helped.
I've also looked into using different methods of compilation like Activator.CreateInstance again no dice.
I don't seem to see a way to load multiple DLLs into the same Assembly class so that I can control the references. Since AppDomains have been removed from .NET Core this doesn't look like it is possible, though I may be mistaken/looking in the wrong area.
If what I'm doing doesn't seem like it will be possible, does anyone know if this kind of functionality can be achieved using a different method? I.e. Roslyn?

I just thought that I would update this question with the solution that I managed to find, just in case someone else was having the same problem as I was. Though I would like to thank #Emrah Süngü for pointing me in the right direction.
Emrah drew my attention to the fact that I needed to import the dependencies of the DLL that I wanted to load in order to invoke the classes stored within it. One way to do this is to extend your app.config in order to import those dependencies - however I wanted to do this at runtime (with projects that I didn't know I was going to run prior starting the program) so I needed to look for another solution.
If you aren't using .NET Core this is relatively simple since AppDomains can be used to load all of the dependencies and execute your code. However, since this has been removed from .NET Core I needed to find another solution that would be compatible.
I toyed with the idea of running a separate process (or Powershell), and changing the working directory so that the process was running in the directory that stored all of the dependencies it needed. However, I couldn't find a way of doing this that allowed me to react to the outcome of running the methods.
Later I investigated manipulating the AssemblyLoadContext class, but (at the time of writing) there is little to no documentation on how this class. I did find this answer which was able to helped significantly... https://stackoverflow.com/a/37896162/6012159
In order for it to work I did have to make a slight change, instead of creating a new AssemblyLoader every time (which would cause exceptions to be thrown when trying to invoke methods within the Assembly), I reused the AssemblyLoader each time (Which removed this problem).
public class AssemblyLoader : AssemblyLoadContext
{
private string folderPath;
public AssemblyLoader(string folderPath)
{
this.folderPath = folderPath;
}
protected override Assembly Load(AssemblyName assemblyName)
{
var deps = DependencyContext.Default;
var res = deps.CompileLibraries.Where(d => d.Name.Contains(assemblyName.Name)).ToList();
if (res.Count > 0)
{
return Assembly.Load(new AssemblyName(res.First().Name));
}
else
{
var apiApplicationFileInfo = new FileInfo($"{folderPath}{Path.DirectorySeparatorChar}{assemblyName.Name}.dll");
if (File.Exists(apiApplicationFileInfo.FullName))
{
return this.LoadFromAssemblyPath(apiApplicationFileInfo.FullName);
}
}
return Assembly.Load(assemblyName);
}
}
Which can be use to load assemblies like this:
string directory = #"C:\Path\To\Project\bin\Debug\netcoreapp1.0\publish\";
string pathToDLL = #"C:\Path\To\Project\bin\Debug\netcoreapp1.0\publish\project.dll";
AssemblyLoader al = new AssemblyLoader(directory);
Assembly assembly = al.LoadFromAssemblyPath(pathToDLL);

I am assuming that "UnitTests.dll" depends on (references) other dll(s) and your program does not know where to look for those referenced dll(s). You should (in fact have to) tell it to where to look for those dll(s) as well. By default is the same directory as your EXE. You can use app.config for telling where else to look. For Load() to succeed dependant dll(s) must be stored in your app's probing path.
That is the reason why you are getting an error.
Here you can find related article.
https://msdn.microsoft.com/en-us/library/823z9h8w.aspx

Exception has been thrown by the target of an invocation - An attempt was made to load a program with an incorrect format. DbGeography [duplicate]

This question already has an answer here:
EF 6 and spatial type DbGeography on Windows Azure
(1 answer)
Closed 6 years ago.
Before I say anything - yes, I've read everything on this question so far, about building in X86/X64 modes and so on. I recently changed PC and have set up my environment again. The code is from a reporting service within a silverlight application. The silverlight application all builds fine and it has been publish ok as well. It just seems there are a few small errors somewhere within the reporting section that don't seem to want to play nice.
double Latitude = (double) parameters["GeofenceLatitude"];
double Longitude = (double) parameters["GeofenceLongitude"];
double Radius = (double) parameters["GeofenceRadius"];
DbGeography Geofence = GetPointFromLatLong(Latitude, Longitude);
Geofence = Geofence.Buffer(Radius);
So everything works fine, the GetPointFromLatLong method (a custom one) returns a correct DbGeography object, however the .Buffer(Radius) causes an exception detailed below.
InnerException = {"An attempt was made to load a program with an incorrect format. (Exception from HRESULT: 0x8007000B)"}
Message = "Exception has been thrown by the target of an invocation."
Source = "mscorlib"
StackTrace = "at System.RuntimeMethodHandle.InvokeMethod(Object target, Object[] arguments, Signature sig, Boolean constructor) at System.Reflection.RuntimeMethodInfo.UnsafeInvokeInternal(Object obj, Object[] parameters, Object[] arguments) at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture) at System.Reflection.MethodBase.Invoke(Object obj, Object[] parameters) at System.Data.Entity.SqlServer.SqlSpatialServices.Buffer(DbGeography geographyValue, Double distance) at System.Data.Entity.Spatial.DbGeography.Buffer(Nullable distance) at GpsSilverlight.Web.Reports.ReportService.OnLoadData(IDictionary`2 parameters, String reportName, ReportSlot reportSlot) in PROJECT:line 1514"
I cannot figure out what's going on here. Does anyone have any experience with this?
static DbGeography GetPointFromLatLong(double Latitude, double Longitude)
{
DbGeography geogTest;
geogTest = DbGeography.PointFromText(string.Format("POINT({1} {0})", Latitude.ToString(), Longitude.ToString()), 4326);
return geogTest;
}

The most common problem when this exception is thrown is that the CLR is running in 32/64 bit mode and is attempting to load an assembly compiled for 64/32 bit mode.
Sometimes solution, project and configuration settings can be a bit confusing and not always producing binaries the way you think.
The best way to verify what the compiler REALLY has done to build your assemblies (or ones you rely on) is to disassemble them and look at the assembly manifest information of all your binaries. Often one assembly is not built in the configuration you think it should.
This type of problem still bugs me sometimes and disassembling usually helps.

C# - System.OutOfMemoryException in Visual Studio

I have a problem, when I right click my main form in Visual Studio and go to 'View Designer' I get an error. It says: 'Exception of type 'System.OutOfMemoryException' was thrown.'
Stacktrace:
at System.Reflection.AssemblyName.nGetFileInformation(String s)
at System.Reflection.AssemblyName.GetAssemblyName(String assemblyFile)
at Microsoft.VisualStudio.Design.VSTypeResolutionService.AssemblyEntry.get_AssemblyName()
at Microsoft.VisualStudio.Design.VSTypeResolutionService.AssemblyEntry.get_FullName()
at Microsoft.VisualStudio.Design.VSTypeResolutionService.AssemblyEntry.get_AssemblySpec()
at Microsoft.VisualStudio.Design.VSTypeResolutionService.SearchProjectEntries(String fullName, Boolean correctThread)
at Microsoft.VisualStudio.Design.VSTypeResolutionService.System.ComponentModel.Design.IDesignTimeAssemblyLoader.GetTargetAssemblyPath(AssemblyName runtimeOrTargetAssemblyName, String suggestedAssemblyPath, FrameworkName targetFramework)
at Microsoft.VisualStudio.Shell.Design.VsTargetFrameworkUniverse.ResolveAssembly(AssemblyName assemblyName, Assembly runtimeAssembly)
at Microsoft.VisualStudio.Shell.Design.VsTargetFrameworkUniverse.GetTypeFromTargetLocation(Type type, Boolean validateBase)
at Microsoft.VisualStudio.Shell.Design.VsTargetFrameworkUniverse.GetType(Type type)
at Microsoft.VisualStudio.Shell.Design.VsTargetFrameworkUtil.GetCustomAttributes(Type type, Type filter, Boolean inherit, CustomAttributesCache cache)
at Microsoft.VisualStudio.Shell.Design.VsTargetFrameworkType.GetCustomAttributes(Type filter, Boolean inherit)
at Microsoft.VisualStudio.Shell.Design.VsTargetFrameworkAttributeCollection.GetAttributes(Type type, Type filter)
at Microsoft.VisualStudio.Shell.Design.VsTargetFrameworkAttributeCollection.GetAttributes(MemberInfo member, Type filter)
at Microsoft.VisualStudio.Shell.Design.VsTargetFrameworkAttributeCollection.get_Attributes()
at System.ComponentModel.AttributeCollection.get_Count()
at Microsoft.VisualStudio.Design.VSDesignSurface.EnsureExtensions(IComponent component)
at Microsoft.VisualStudio.Design.VSDesignSurface.CreateInstance(Type type)
at System.ComponentModel.Design.DesignerHost.System.ComponentModel.Design.IDesignerHost.CreateComponent(Type componentType, String name)
at System.ComponentModel.Design.Serialization.DesignerSerializationManager.CreateInstance(Type type, ICollection arguments, String name, Boolean addToContainer)
at System.ComponentModel.Design.Serialization.DesignerSerializationManager.System.ComponentModel.Design.Serialization.IDesignerSerializationManager.CreateInstance(Type type, ICollection arguments, String name, Boolean addToContainer)
at System.ComponentModel.Design.Serialization.TypeCodeDomSerializer.Deserialize(IDesignerSerializationManager manager, CodeTypeDeclaration declaration)
at System.ComponentModel.Design.Serialization.CodeDomDesignerLoader.PerformLoad(IDesignerSerializationManager manager)
at Microsoft.VisualStudio.Design.Serialization.CodeDom.VSCodeDomDesignerLoader.PerformLoad(IDesignerSerializationManager serializationManager)
at System.ComponentModel.Design.Serialization.BasicDesignerLoader.BeginLoad(IDesignerLoaderHost host)
Designer:
http://pastebin.com/hdRB5DAj
I got this error this morning, but I still haven't resolved it. If anyone could help me I would really appreciate it!
I'm only using ~55% of all my RAM, so that can't be it.

As Dr Hebie points out, it's doubtful that it's VS itself throwing the OOM exception, but something in your form constructor.
A Technique I've used to great success with this is opening the form code and inserting Throw new Exception("Message describing position") at the start of the constructor. Hopefully, now instead of getting an OOM exception, you'll get the exception you just specified. Now move this exception around until you get the OOM exception. This will show you the line of code that is causing the OOM.
Good luck!

There are multiple things that this can be caused by, and the problem gets worse with older version of Visual Studio (2005 was particularly bad in my experience).
As this is happening when you view the designer of a form, there is a chance that this is due to objects being created in your form's constructor or event handlers. When VS loads your form into the designer it will actually compile and create an instance of the form class. Any objects you create within the form are likely to get created at this time as well. All this happens within Visual Studio's memory allocation so if you are allocating a large amount of memory this can hinder Visual Studio's memory handling.
I would suggest you perform a check on the DesignMode property of the form and only load/create instances of data classes (like Views) when that property is false. You should also be prepared to do this in event handlers throughout the form as these can be fired by the Visual Studio designer.
Alternatively, if you're feeling brave, you can actually debug Visual Studio with itself! Open your project in VS and then open another instance of VS. In the second instance use the Debug -> Attach to Process option and attach to the first VS instance. Now open the designer for your form and see if you can identify where the error occurs. You may have to switch on the 'break on thrown exceptions' settings under Debug -> Exceptions in the second VS instance to ensure your debugging session sees all exceptions.
Good Luck.

Unknown name ComException on a referenced dll in a C# project

I'm writting a C# application which use one of the dll written in C++ as reference. I can use that dll namespace and my project compiles fine. However when I run it I keep getting error in one of the line where I assign a property its value. The exception error I got was the following:
A first chance exception of type 'System.Runtime.InteropServices.COMException' occurred in mscorlib.dll
2013-06-03 12:26:32 - Unknown name. (Exception from HRESULT: 0x80020006 (DISP_E_UNKNOWNNAME))
2013-06-03 12:26:32 - at System.RuntimeType.InvokeDispMethod(String name, BindingFlags invokeAttr, Object target, Object[] args, Boolean[] byrefModifiers, Int32 culture, String[] namedParameters)
2013-06-03 12:26:32 - at System.RuntimeType.InvokeMember(String name, BindingFlags bindingFlags, Binder binder, Object target, Object[] providedArgs, ParameterModifier[] modifiers, CultureInfo culture, String[] namedParams)
2013-06-03 12:26:32 - at System.RuntimeType.ForwardCallToInvokeMember(String memberName, BindingFlags flags, Object target, Int32[] aWrapperTypes, MessageData& msgData)
2013-06-03 12:26:32 - at sstObjTapLib._DsstObjTap.set_CapCode(String )
2013-06-03 12:26:32 - at hpOutput.CTapPagerCom.MessageLoop() in c:\shs\Arial 8.1\XmarkClient\hpOutput\CTapPagerCom.cs:line 225
I initiated the dll object using the following code:
m_ctlTap = new sstObjTapLib.ctlTap();
Below are the three screenshots:
The properties of the DLL I use
The object browser of the dll I use
A breakpoint that shows where the exception occurs.
Looking at the stack error above, it seems that .NET is trying to call some method that does not exist, but I'm just setting a property value. Can somebody point me in the right direction or what I might have missed?
A noted point: While in debugging, I'm looking at my loaded module view, however I don't see this dll name one in the list of my loaded module.

I'm not sure why but the computer I worked with had this same dll installed. I know this by viewing it using the third party tool called RegDllView .
So I went in, unregister the dll I was using, verify it is also gone from the registry and then re-register it again. Clean out my project and recompile everything, and got the exact code to work.
Looking at what I did I think for some reason the application did not recognize the GUID supplied to point to the proper COM.

Compiler Issue in Windows 7: A generic error occurred in GDI+

We have an application that we need to begin testing and developing in Windows 7 environment. It works fine compiling under WinXP in VS2008, no problems. However when I went to compile it on a windows 7 machine using VS2008 today I get the following error:
Error 12 The "GenerateResource" task failed unexpectedly.
System.Runtime.InteropServices.ExternalException (0x80004005): A generic error occurred in GDI+.
at System.Drawing.Image.Save(Stream stream, ImageCodecInfo encoder, EncoderParameters encoderParams)
at System.Drawing.Image.Save(MemoryStream stream)
at System.Drawing.Image.System.Runtime.Serialization.ISerializable.GetObjectData(SerializationInfo si, StreamingContext context)
at System.Runtime.Serialization.Formatters.Binary.WriteObjectInfo.InitSerialize(Object obj, ISurrogateSelector surrogateSelector, StreamingContext context, SerObjectInfoInit serObjectInfoInit, IFormatterConverter converter, ObjectWriter objectWriter, SerializationBinder binder)
at System.Runtime.Serialization.Formatters.Binary.WriteObjectInfo.Serialize(Object obj, ISurrogateSelector surrogateSelector, StreamingContext context, SerObjectInfoInit serObjectInfoInit, IFormatterConverter converter, ObjectWriter objectWriter, SerializationBinder binder)
at System.Runtime.Serialization.Formatters.Binary.ObjectWriter.Serialize(Object graph, Header[] inHeaders, __BinaryWriter serWriter, Boolean fCheck)
at System.Runtime.Serialization.Formatters.Binary.BinaryFormatter.Serialize(Stream serializationStream, Object graph, Header[] headers, Boolean fCheck)
at System.Runtime.Serialization.Formatters.Binary.BinaryFormatter.Serialize(Stream serializationStream, Object graph)
at System.Resources.ResourceWriter.WriteValue(ResourceTypeCode typeCode, Object value, BinaryWriter writer, IFormatter objFormatter)
at System.Resources.ResourceWriter.Generate()
at System.Resources.ResourceWriter.Dispose(Boolean disposing)
at System.Resources.ResourceWriter.Close()
at Microsoft.Build.Tasks.ProcessResourceFiles.WriteResources(IResourceWriter writer)
at Microsoft.Build.Tasks.ProcessResourceFiles.WriteResources(String filename)
at Microsoft.Build.Tasks.ProcessResourceFiles.ProcessFile(String inFile, String outFile)
at Microsoft.Build.Tasks.ProcessResourceFiles.Run(TaskLoggingHelper log, ITaskItem[] assemblyFilesList, List`1 inputs, List`1 outputs, Boolean sourcePath, String language, String namespacename, String resourcesNamespace, String filename, String classname, Boolean publicClass)
at Microsoft.Build.Tasks.ProcessResourceFiles.Run(TaskLoggingHelper log, ITaskItem[] assemblyFilesList, List`1 inputs, List`1 outputs, Boolean sourcePath, String language, String namespacename, String resourcesNamespace, String filename, String classname, Boolean publicClass)
at Microsoft.Build.Tasks.GenerateResource.Execute()
at Microsoft.Build.BackEnd.TaskExecutionHost.Microsoft.Build.BackEnd.ITaskExecutionHost.Execute()
at Microsoft.Build.BackEnd.TaskBuilder.ExecuteInstantiatedTask(ITaskExecutionHost taskExecutionHost, TaskLoggingContext taskLoggingContext, TaskHost taskHost, ItemBucket bucket, TaskExecutionMode howToExecuteTask, Boolean& taskResult)
I cannot for the life of me run this one down. I have visited the msdn forums and find that it is an issue for a lot of people, but no consistent solution has been provided by MS or anyone else.
Has anyone seen this before and fixed it? Please advise is needed!
Thanks

I compiled using the command line msbuild and that identified the problem location.
It was a resx file in a class which had one unused image in it. I removed that and all was good again. Can build fine now.

After hours of troubleshooting, I opened and built the project using the VS 2010 command line prompt using MSBUILD "my solution file path here". This provided a more visible sequence of build events, and I found my project was failing just after it compiled form 16. The forms compiling appeared to be going in order of the objects in the solution explorer. So I checked the next form and found it contained a picture box. I also checked the form after that one and found I could not open the designer without errors(object reference not set to instance of object). So apparently, the problem was now two-fold.
To resolve I had to remove the picture box object from the first form I identified as problematic (it was not being used any way) as it appeared to be corrupted. I found the second form with the null reference exception was using a user control. The code for the constructor of the user control was attempting to pass an object to a container before calling InitializeComponent(). This created the null reference since the container hadn't event been created in InitializeComponent when the problematic code was called.
After resolving the issues in the above paragraph my solution compiled under Windows 7.

There is a GDI update for Windows 7, I think, if I'm not mistaken. Maybe that will solve the issue. Does your solution build using Msbuild on the commsnd line?

Do you use TIFF images in your app?
Some time ago, I also had a problem with TIFF images as part of reports that wouldn't compile under Win7 x64 although it compiled like a charm under Vista x86. The error message also involved GDI+. I saved the images under a different format (PNG) and the problem vanished.
At the time (around March 2011), I first ensured that my Windows was up-to-date but it didn't solve the problem. So maybe there is such an update as mentionned by Erik but it didn't come through Windows Update back then (Maybe it's newer).

Delete the resources from the resource manager (right click on each and delete) then add them back. for me it solve the problem.

i had same problem.
i just used msbuild myProject.sln command and it fixed and built successfully with no errors! now i can manually build my solution.
no need to reAdding my resources