Type.GetType(String) not working

**code4life** · Apr 27 '06, 01:33 AM

Actually you need to pass the fully qualified assembly name. The following example will reveal that more than just "System.Windows .Forms.Button" is required:

// I'm assuming this will go into a winform project, since you're referring to a button... you can call this method from the form you copy it over to.
public static void TypeTest()
{
//the actual string will be "System.Windows .Forms.Button, System.Windows. Forms, Version=2.0.0.0 , Culture=neutral , PublicKeyToken= b77a5c561934e08 9" -- when you debug the code, this will become evident...
string fullyqualifiedn ame = new Button().GetTyp e().AssemblyQua lifiedName;
MessageBox.Show (fullyqualified name);
MessageBox.Show (System.Type.Ge tType(fullyqual ifiedname).Name );
}

Originally posted by Gugale at Lincoln

In my code Type.GetType(te xt) works when text="System.IO .File". However, it
doesn't work when text="System.Wi ndows.Forms.But ton". In general it works
for classes in System.dll assembly. Is there anyway I can make it work for
classes in System.Windows. Forms.dll assembly?

Thanks
SG

**Barry Kelly** · Apr 27 '06, 01:55 AM

Re: Type.GetType(St ring) not working

"Gugale at Lincoln" <phaltu0-0@yahoo.com> wrote:
[color=blue]
> In my code Type.GetType(te xt) works when text="System.IO .File". However, it
> doesn't work when text="System.Wi ndows.Forms.But ton". In general it works
> for classes in System.dll assembly. Is there anyway I can make it work for
> classes in System.Windows. Forms.dll assembly?[/color]

I'm not sure why it won't work trivially for Button. Perhaps it is to do
with multiple System.Windows. Forms assemblies, one each for 1.1 and 2.0?
I'm not sure.

You can however still load the button class as long as you fully qualify
the type:

| Type.GetType("S ystem.Windows.F orms.Button, System.Windows. Forms, Culture=neutral , Version=2.0.0.0 , PublicKeyToken= b77a5c561934e08 9")

-- Barry

**Mattias Sjögren** · Apr 27 '06, 06:05 AM

Re: Type.GetType(St ring) not working

>I'm not sure why it won't work trivially for Button. Perhaps it is to do[color=blue]
>with multiple System.Windows. Forms assemblies, one each for 1.1 and 2.0?
>I'm not sure.[/color]

No it's because when you don't specify the assembly name, Type.GetType
only looks in mscorlib.dll and the calling assembly. That works for
System.IO.File but not something in the Winforms assembly.

Mattias

--
Mattias Sjögren [C# MVP] mattias @ mvps.org
http://www.msjogren.net/dotnet/ | http://www.dotnetinterop.com
Please reply only to the newsgroup.

**Jon Skeet [C# MVP]** · Apr 27 '06, 06:45 AM

Re: Type.GetType(St ring) not working

Barry Kelly <barry.j.kelly@ gmail.com> wrote:[color=blue]
> "Gugale at Lincoln" <phaltu0-0@yahoo.com> wrote:
>[color=green]
> > In my code Type.GetType(te xt) works when text="System.IO .File". However, it
> > doesn't work when text="System.Wi ndows.Forms.But ton". In general it works
> > for classes in System.dll assembly. Is there anyway I can make it work for
> > classes in System.Windows. Forms.dll assembly?[/color]
>
> I'm not sure why it won't work trivially for Button. Perhaps it is to do
> with multiple System.Windows. Forms assemblies, one each for 1.1 and 2.0?
> I'm not sure.[/color]

From the docs of Type.GetType(st ring):

<quote>
If typeName includes only the name of the Type, this method searches in
the calling object's assembly, then in the mscorlib.dll assembly. If
typeName is fully qualified with the partial or complete assembly name,
this method searches in the specified assembly.
</quote>

(The OP is mistaken about types from System.dll - System.IO.File, for
instance, is in mscorlib.dll. Trying a type which is genuinely in
System.dll, such as System.IO.FileS ystemWatcher, returns null as
expected given the above docs.)

--
Jon Skeet - <skeet@pobox.co m>
http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet
If replying to the group, please do not mail me too

**Barry Kelly** · Apr 27 '06, 12:58 PM

Re: Type.GetType(St ring) not working

Mattias Sjögren <mattias.dont.w ant.spam@mvps.o rg> wrote:
[color=blue][color=green]
> >I'm not sure why it won't work trivially for Button. Perhaps it is to do
> >with multiple System.Windows. Forms assemblies, one each for 1.1 and 2.0?
> >I'm not sure.[/color]
>
> No it's because when you don't specify the assembly name, Type.GetType
> only looks in mscorlib.dll and the calling assembly. That works for
> System.IO.File but not something in the Winforms assembly.[/color]

At first I thought it was just what you mentioned, that the assembly name
is missing. But it's more than that.

If you try it with just the class name and assembly name and without the
Version, Culture and PublicKeyToken fields it still doesn't work. You need
all fields for it to work.

-- Barry

**Barry Kelly** · Apr 27 '06, 01:06 PM

Re: Type.GetType(St ring) not working

Jon Skeet [C# MVP] <skeet@pobox.co m> wrote:
[color=blue]
> From the docs of Type.GetType(st ring):
>
> <quote>
> If typeName includes only the name of the Type, this method searches in
> the calling object's assembly, then in the mscorlib.dll assembly. If
> typeName is fully qualified with the partial or complete assembly name,
> this method searches in the specified assembly.
> </quote>[/color]

If you try

| Type.GetType("S ystem.Windows.F orms.Button, System.Windows. Forms")

you'll find it returns null, at least when you have both .NET 1.1 and 2.0
installed (I'm guessing). I tried before posting.

-- Barry

**Jon Skeet [C# MVP]** · Apr 27 '06, 04:35 PM

Re: Type.GetType(St ring) not working

Barry Kelly <barry.j.kelly@ gmail.com> wrote:[color=blue][color=green]
> > <quote>
> > If typeName includes only the name of the Type, this method searches in
> > the calling object's assembly, then in the mscorlib.dll assembly. If
> > typeName is fully qualified with the partial or complete assembly name,
> > this method searches in the specified assembly.
> > </quote>[/color]
>
> If you try
>
> | Type.GetType("S ystem.Windows.F orms.Button, System.Windows. Forms")
>
> you'll find it returns null, at least when you have both .NET 1.1 and 2.0
> installed (I'm guessing). I tried before posting.[/color]

I don't think that counts as "enough" of the assembly name - I think
you need to give at least some of the version number. Certainly if you
give the *complete* assembly name (with full version number) it will
work. There's more to an "assembly name" than the file name. It's not
terribly well documented, unfortunately.

--
Jon Skeet - <skeet@pobox.co m>
http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet
If replying to the group, please do not mail me too

**Gugale at Lincoln** · Apr 27 '06, 05:36 PM

Re: Type.GetType(St ring) not working

Thanks Barry!

In case if anyone is wondering, as I did, you can get version number and
public key using[color=blue]
>gacutil /l assemblyname[/color]
from Visual Studio .Net Command Prompt

"Barry Kelly" <barry.j.kelly@ gmail.com> wrote in message
news:4t60525u5s 396jc4jovblngut pj2ksqvei@4ax.c om...[color=blue]
> "Gugale at Lincoln" <phaltu0-0@yahoo.com> wrote:
>[color=green]
>> In my code Type.GetType(te xt) works when text="System.IO .File". However,
>> it
>> doesn't work when text="System.Wi ndows.Forms.But ton". In general it works
>> for classes in System.dll assembly. Is there anyway I can make it work
>> for
>> classes in System.Windows. Forms.dll assembly?[/color]
>
> I'm not sure why it won't work trivially for Button. Perhaps it is to do
> with multiple System.Windows. Forms assemblies, one each for 1.1 and 2.0?
> I'm not sure.
>
> You can however still load the button class as long as you fully qualify
> the type:
>
> | Type.GetType("S ystem.Windows.F orms.Button, System.Windows. Forms,
> Culture=neutral , Version=2.0.0.0 , PublicKeyToken= b77a5c561934e08 9")
>
> -- Barry[/color]

**Barry Kelly** · Apr 27 '06, 06:25 PM

Re: Type.GetType(St ring) not working

Jon Skeet [C# MVP] <skeet@pobox.co m> wrote:
[color=blue]
> Barry Kelly <barry.j.kelly@ gmail.com> wrote:[color=green]
> > If you try
> >
> > | Type.GetType("S ystem.Windows.F orms.Button, System.Windows. Forms")
> >
> > you'll find it returns null, at least when you have both .NET 1.1 and 2.0
> > installed (I'm guessing). I tried before posting.[/color]
>
> I don't think that counts as "enough" of the assembly name - I think
> you need to give at least some of the version number. Certainly if you
> give the *complete* assembly name (with full version number) it will
> work. There's more to an "assembly name" than the file name. It's not
> terribly well documented, unfortunately.[/color]

The version number isn't enough. You also need *both* the Culture *and*
PublicKeyToken. I tried pretty much every combination.

I've used this method myself for extensibility scenarios, and all the
times I've used it I've only needed the type name and assembly name - I've
never seen the behaviour that System.Windows. Forms.Button manifests.

Odd. <g>

-- Barry

Type.GetType(String) not working

Type.GetType(String) not working

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