I am trying to write my own httpModule in f# web api, I am using visual studio 2015. I was able write the code in C# but when I try same code in f# , I get error that it is unable to load class from assembly
TestHttpMod1 is class name derived from IHttpModule,
TestHttpMod is module name
FSharp is namespace
FSharp is workspace name.
I have 2 questions
Can I get some reference code in F# where HttpModule is implemented in web api
or
How to solve the error?(exact error is as below)
"Could not load type 'FSharp.TestHttpMod.TestHttpMod1' from assembly 'FSharp'."
Below is configuration done in web config
<modules>
<add name="TestHttpMod1" type ="FSharp.TestHttpMod.TestHttpMod1, FSharp"/>
<modules/>
Regards,
Amit Bhagwat
Related
How do I subscribe to an event implemented in F# from a C# client?
I have the following code:
_dispatcher.SignInRequested += StartActivity(typeof(SignInActivity));
This line results in the following error:
Error CS0012 The type 'FSharpHandler<>' is defined in an assembly that
is not referenced. You must add a reference to assembly 'FSharp.Core,
Version=3.3.1.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'.
I attempted to troubleshoot and found this:
However, I do not understand the answer. My events are defined under a namespace and not a module. Hence, me not understanding the reasoning of that discussion.
I then tried adding the following reference to my C# project:
FSharp.Core 4.0.0.1
and
FSharp.Core 3.1.2.5
However, I still receive the same error.
When managing Nuget packages, I do not see the version "3.3.1.0" listed as an option.
Implementation Details:
The signature of the signin event from the C# client is the following:
public event FSharpHandler<Unit> SignInRequested;
I actually declare the event as the following:
let signInRequested = new Event<_>()
Any suggestions?
You need to have a look at the CLIEventAttribute . Events declared from F# cannot be used from C# unless they are declared with this attribute.
I am trying to make use of the ImmutableDictionary in F# using Mono. I'm using the Xamarin IDE.
I have set my target framework to Mono/.Net4.5 and imported the System.Collections.Immutable using the built in Nuget package manager.
The following line
open System.Collections.Immutable
is generating the following two errors
'/Users/UserName/Projects/Xamarin/OrderInfer/OrderInference/MyTest.fs(34,34): Error FS1109: A reference to the type 'System.Collections.Generic.IEnumerable'1' in assembly 'System.Runtime' was found, but the type could not be found in that assembly (FS1109) (MyTest)'
/Users/UserName/Projects/Xamarin/OrderInfer/OrderInference: Error FS1108: The type 'Lazy'2' is required here and is unavailable. You must add a reference to assembly 'System.ComponentModel.Composition, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'. (FS1108) (OrderInference)
The 2nd error suggests I need to reference System.ComponentModel.Composition. Am I able to use it in Mono? If so, is there another assembly I need to reference?
EDIT:
Solution removed and reposted below as an answer
This problem can be solved by adding a reference to: 'System.ComponentModel.Composition'. In Xamarin's IDE, this is done by using the Edit References Dialog which can be found by right-clicking on the reference in your project. Go to the All tab and search for System.ComponentModel and just add the System.ComponentModel.Composition assembly.
I now have the following two assemblies installed:
System.Collections.Immutable.dll
System.ComponentModel.Composition.dll
My code now reads:
open System
open System.ComponentModel.Composition
open System.Collections.Immutable
type wordPairs = { pairs:ImmutableDictionary<string, string>; count:int}
let myPairs = {pairs = ImmutableDictionary.Create<string, string>(); count = 0}
Note: As gradbot pointed out (and Immo Landwerth later nitpicked about ;>> ), ImmutableDictionary is a abstract sealed class. And as such, it has no public constructors. So you need to use the .Create method.
ImmutableDictionary is abstract so new won't work. It does however provide a number of create methods.
ImmutableDictionary.Create<string, string>()
I have a question related to the code provided in an answer to this question.
The problem I have is that the three referenced assmeblies (System.dll, FSharp.Core.dll, FSharp.Powerpack.dll) that are passed to CompilerParameters are not found at runtime. The error I get is:
unknown-file(0,0) : error 0: error FS0218: Unable to read assembly
'c:\user s\utente\documents\visual studio
2010\Projects\TrashSolution\TrashSolution\bin\D ebug\FSharp.Core.dll'
How do I tell the compiler to search for these assemblies in the GAC, instead of the project's bin directory? If I open a namespace in the code provided as a string, how do I know which assemblies to add? Where can I get this information?
In the code from the answer you linked, there's a line towards the bottom:
let asm = Reflection.Assembly.LoadFrom(fileinfo.Value.FullName)
If you call Reflection.Load instead and pass it the fully-qualified assembly name, it'll try to load the assembly from the GAC (and a few other places, if the assembly isn't in the GAC).
let asm =
Assembly.Load "SampleAssembly, Version=1.0.2004.0, Culture=neutral, PublicKeyToken=8744b20f8da049e3"
If you don't know the fully-qualified assembly name you have to create an AssemblyName with the simple name of the assembly, then call the Reflection.Load overload which takes an AssemblyName instead of a string.
let asmName = AssemblyName "Your.Assembly.Name"
let asm = Assembly.Load asmName
As far as knowing which assemblies to load -- I don't think there's a simple way to determine that programmatically. The only two solutions I can think of right now:
If you have some knowledge about the code you're being given (as a string), you could parse it with the FSharpCodeProvider and look at which namespaces/modules are opened and which types are used. If you're looking to see if some particular namespace or type is used (i.e., that you would need to include an assembly reference for when compiling the code), you could create a Map (in your .fsx which is doing the compilation) of namespaces and/or type names to assembly names and use it to reference the appropriate assemblies.
You could "brute-force" search the GAC, by using the semi-documented Fusion API to enumerate all of the assemblies installed in the GAC, then using Reflection to examine each assembly and determine if it's one you require. This is likely to be extremely slow, so I'd avoid it at all costs. If you do decide to go this route, you must also use the Assembly.ReflectionOnlyLoad method to load the assemblies! This allows the assemblies to be unloaded after you finish examining them -- if you use normal Reflection the assemblies can't be unloaded and your program will likely crash with an OutOfMemoryException or similar.
EDIT: Turns out that loading the assembly by its simple name succeeds in fsi and not in normal F# code because fsi automatically installs a handler for the AppDomain.AssemblyResolve event. This event is triggered by the CLR when you try to load an assembly and it can't be resolved; the event provides a way for you to "manually" resolve the assembly and/or generate an assembly dynamically and return it.
If you look at the FileNotFoundException raised when you try to run the code in an F# project, you'll see something like this in the Fusion Log property of the exception:
=== Pre-bind state information ===
LOG: User = Jack-Laptop\Jack
LOG: DisplayName = System
(Partial)
WRN: Partial binding information was supplied for an assembly:
WRN: Assembly Name: System | Domain ID: 1
WRN: A partial bind occurs when only part of the assembly display name is provided.
WRN: This might result in the binder loading an incorrect assembly.
WRN: It is recommended to provide a fully specified textual identity for the assembly,
WRN: that consists of the simple name, version, culture, and public key token.
WRN: See whitepaper http://go.microsoft.com/fwlink/?LinkId=109270 for more information and common solutions to this issue.
LOG: Appbase = file:///C:/Users/Jack/Documents/Visual Studio 2010/Projects/StackOverflow1/StackOverflow1/bin/Debug/
LOG: Initial PrivatePath = NULL
Calling assembly : StackOverflow1, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null.
===
LOG: This bind starts in default load context.
LOG: No application configuration file found.
LOG: Using host configuration file:
LOG: Using machine configuration file from C:\Windows\Microsoft.NET\Framework64\v4.0.30319\config\machine.config.
LOG: Policy not being applied to reference at this time (private, custom, partial, or location-based assembly bind).
LOG: Attempting download of new URL file:///C:/Users/Jack/Documents/Visual Studio 2010/Projects/StackOverflow1/StackOverflow1/bin/Debug/System.DLL.
LOG: Attempting download of new URL file:///C:/Users/Jack/Documents/Visual Studio 2010/Projects/StackOverflow1/StackOverflow1/bin/Debug/System/System.DLL.
LOG: Attempting download of new URL file:///C:/Users/Jack/Documents/Visual Studio 2010/Projects/StackOverflow1/StackOverflow1/bin/Debug/System.EXE.
LOG: Attempting download of new URL file:///C:/Users/Jack/Documents/Visual Studio 2010/Projects/StackOverflow1/StackOverflow1/bin/Debug/System/System.EXE.
Looking towards the bottom of that log, you'll see where the CLR searched for the assembly before it gave up.
Here's a simple handler to give you an idea of how to use the AppDomain.AssemblyResolve handler to manually resolve the assembly. (NOTE: The handler needs to be added before the code that attempts to load the assembly!)
System.AppDomain.CurrentDomain.add_AssemblyResolve (
System.ResolveEventHandler (fun _ args ->
let resolvedAssembly =
System.AppDomain.CurrentDomain.GetAssemblies ()
|> Array.tryFind (fun loadedAssembly ->
// If this assembly has the same name as the one we're looking for,
// assume it's correct and load it. NOTE : It may not be the _exact_
// assembly we're looking for -- then you'll need to adjust the critera below.
args.Name = loadedAssembly.FullName
|| args.Name = loadedAssembly.GetName().Name)
// Return null if the assembly couldn't be resolved.
defaultArg resolvedAssembly null))
If you add that code to a new F# console project, followed by the code which uses AssemblyName with Assembly.Load, you should be able to load the System assembly because it's referenced by default in an F# project and it'll be loaded when you run the project. If you try to resolve System.Drawing, it'll fail because our custom event handler can't find the assembly. Obviously, if you need some more complicated assembly-resolving logic, you should build that into the event handler in whatever way makes sense for your application.
Finally, here's a link to the MSDN whitepaper mentioned in the exception message: Best Practices for Assembly Loading. It's worth a read if you get stuck and can't figure out how to resolve the assemblies you need.
I am trying to use SVCUTIL from the SDK to generate the common types in several web services. When I try to generate code I get the errors (shown at the bottom)- these suggest the WSDL is broken. However, if I import the service in ServiceReferences Visual Studio does not complain. Is SVCUTIL broken?
The WSDLs are public and are:
http://test.wlr3.net/empws/services/WLR3AssuranceServices?wsdl
http://test.wlr3.net/empws/services/WLR3BillingServices?wsdl
http://test.wlr3.net/empws/services/WLR3DialogueServices?wsdl
http://test.wlr3.net/empws/services/WLR3FulfillmentServices?wsdl
http://test.wlr3.net/empws/services/WLR3InventoryServices?wsdl
http://test.wlr3.net/empws/services/WLR3InventoryOrderServices?wsdl
http://test.wlr3.net/empws/services/WLR3InventoryTroubleReportServices?wsdl
http://test.wlr3.net/empws/services/WLR3InventoryWorkItemServices?wsdl
http://test.wlr3.net/empws/services/WLR3IssueServices?wsdl
http://test.wlr3.net/empws/services/WLR3ReportingServices?wsdl
http://test.wlr3.net/empws/services/WLR3SecurityServices?wsdl
If you check these out you'll see a lot of common types and several namespaces. I've tried sending these to SVCUTIL to generate the code but it doesn't like the FulfillmentServices and the InventoryServices ones:
Error: Cannot import wsdl:portType
Detail: An exception was thrown while running a WSDL import extension: System.ServiceModel.Description.XmlSerializerMessageContractImporter
Error: Cannot import invalid schemas. Compilation on the XmlSchemaSet failed.
XPath to Error Source: //wsdl:definitions[#targetNamespace='http://imperatives.co.uk/V20']/wsdl:portType[#name='WLR3FulfilmentServices']
Error: Cannot import wsdl:binding
Detail: There was an error importing a wsdl:portType that the wsdl:binding is dependent on.
XPath to wsdl:portType: //wsdl:definitions[#targetNamespace='http://imperatives.co.uk/V20']/wsdl:portType[#name='WLR3FulfilmentServices']
XPath to Error Source: //wsdl:definitions[#targetNamespace='http://imperatives.co.uk/V20']/wsdl:binding[#name='WLR3FulfillmentServicesHttpBinding']
Error: Cannot import wsdl:port
Detail: There was an error importing a wsdl:binding that the wsdl:port is dependent on.
XPath to wsdl:binding: //wsdl:definitions[#targetNamespace='http://imperatives.co.uk/V20']/wsdl:binding[#name='WLR3FulfillmentServicesHttpBinding']
XPath to Error Source: //wsdl:definitions[#targetNamespace='http://imperatives.co.uk/V20']/wsdl:service[#name='WLR3FulfillmentServices']/wsdl:port[#name='WLR3FulfillmentServicesHttpPort']
As per comments to the question, there is a small difference in the two problem WSDLs. I compared these with older versions and found there is a type in these based on a virtual base type called "Dto".
This is applied to only two types - one in the Fulfillment Services and one in the Inventory Services, and these are also found in other WSDLs but without the base - the WSDL files are not consistent.
So I can exponerate SVCUTIL here and give the supplier a kick..
Thanks to John Saunders for looking at it
i have this code in one of my asp.net mvc views:
<%Html.RenderFile(#"C:\Members\newsletters\welcome.html");%>
I have created an extension on the Html class to read in a file. the code looks like this:
public static class HtmlRenderer
{
public static void RenderFile(this HtmlHelper helper_, string path_)
{
var reader = new StreamReader(path_);
var contents = reader.ReadToEnd();
helper_.ViewContext.HttpContext.Response.Write(contents);
}
}
This all works perfectly when i run in visual studio on my desktop but when i ftp these files to the server, i get the following error in the browser:
Compiler Error Message: CS1061: 'System.Web.Mvc.HtmlHelper' does not contain a definition for 'RenderFile' and no extension method 'RenderFile' accepting a first argument of type 'System.Web.Mvc.HtmlHelper' could be found (are you missing a using directive or an assembly reference?)
The HtmlRenderer class is in a namespace with my controllers so there is no other external assembly reference needed.
Does anyone have any idea how this could be happening or what i am doing wrong ?
You need to compile the project and then deploy (xcopy or publish from VS) to the server.
Googled and found something.Does the server has .net 3.5?
Try to publish the web on a local IIS7 or IIS6.( Right click project "Publish" ).
You have a good chance you already get a more specific error during "publish".
If not run the page on your local IIS6 or 7 and see if you get an error.
i tried doing a full refresh (deleting everything on the server and republishing and now everything works fine..
so i am happy that everything is working but still have no clue why it wasn't before.