How do I get the Category of the containerID?

Question

When I go to Control Panel --> Device and Printers I see that there is a category for the computer. I can get some metadata from the containerID for the computer itself. But I can't get Category which it belongs to. I see in the bottom of the page that it shows which category it belongs to. But when try to specify the property System.Devices.Category it always return null.

The reason I ask this is because I want to know in the metro app if the unit is a desktop or a notebook.

Thank you in advance

Answer 1

Lex,

I am looking into this. 

Best Wishes - Eric

Answer 2

Lex,

Why is it important to know if this is a desktop or a notebook?

Best Wishes - Eric

Answer 3

Hi Eric, thank you for the reply. In my app the user can register her/himself. In my case is because I want to know which form factor is most popular in my user base.

Thank you once again

Answer 4

Lex,

You can use the GUID PID form of DEVPKEY_DeviceDisplay_Category http://msdn.microsoft.com/en-us/library/windows/hardware/ff542348(v=VS.85).aspx
Example:

"{78c34fc8-104a-4aca-9ea4-524d52996e57} 90”

Please note that it is important to avoid form factor specific app designs. The app should work the same across all form factors. 

Best Wishes - Eric

Answer 5

Hi Eric, thank you for posting a reply. But I am still having problems.

If I understood right (and after reading some references) if there is no canonical name I can use the format {GUI} pid. And indeed I made a test. I was able to retrieve System.Devices.ModelName and when I try to use the format "{656A3BB3-ECC0-43FD-8477-4AE0404A96CD} 8194" I get the same value.

My code is JavaScript and I am making use of

Windows.Devices.Enumeration.Pnp.PnpObject.findAllAsync

where as properties to retrieve I am passing an array (trying the canonical name or the {guid} pid).

My understanding is that every device container has a category associated to it. Is that right?

Also using this URL as reference: http://msdn.microsoft.com/en-us/library/windows/desktop/dd391623(v=vs.85).aspx I could not find the pid 90 (I did find 91 to 94 for the categories but all of them return null).

Yeap. I trying to get this information but I am not making any UI change based on that. Thanks for the heads up.

Thank you once again

Lex

Answer 6

Hi Lex,

System.Devices.Category was introduced in Win7 for use through Devices and Printers (D&P). D&P extensions could use the canonical name to get the category to display.  Due to this, System.Devices.Category maps to DEVPKEY_DeviceContainer_Category_Desc_Singular not DEVPKEY_DeviceContainer_Category.  In your case you're really after DEVPKEY_DeviceContainer_Category. From DevPkey.h

DEFINE_DEVPROPKEY(DEVPKEY_DeviceContainer_Category, 0x78c34fc8, 0x104a, 0x4aca, 0x9e, 0xa4, 0x52, 0x4d, 0x52, 0x99, 0x6e, 0x57, 90); // DEVPROP_TYPE_STRING_LIST
DEFINE_DEVPROPKEY(DEVPKEY_DeviceContainer_Category_Desc_Singular, 0x78c34fc8, 0x104a, 0x4aca, 0x9e, 0xa4, 0x52, 0x4d, 0x52, 0x99, 0x6e, 0x57, 91); // DEVPROP_TYPE_STRING_LIST

For now, if you want to get at DEVPKEY_DeviceContainer_Category you must use the the GUID + PID form through the Windows.Devices.Enumeration API. As Eric mentioned, "{78c34fc8-104a-4aca-9ea4-524d52996e57} 90” is what you want.  This should return an array of strings, not a single string as the underlying property type is DEVPROP_TYPE_STRING_LIST. Keep that in mind when working with your JS code.

If you still have problems getting the category, you can double check your PC is getting a category properly assigned by running this command line:

start /wait ddodiag.exe -o output.xml

Open output.xml and look for the parent node <DDO instanceId="DDO:{00000000-0000-0000-FFFF-FFFFFFFFFFFF}">. That node represents the container of the PC.  Under that node you should see a <PropertyStore propertyCount="XX">.  This contains all the properties on the container. Under there look for the entry for PKEY_DeviceDisplay_Category and see what is listed. You should see at least one device category.

Thanks,
Ben

Answer 7

Hi Ben, thank you for the information. really good stuff.

Something interesting happened. I tried to user {78c34fc8-104a-4aca-9ea4-524d52996e57} 90, as Eric suggested, and it returned null (tried several times). But after I ran the ddodiag that you suggested I saw the information over there and when I ran the code with {78c34fc8-104a-4aca-9ea4-524d52996e57} 90 I managed to get an array with the info.

Thank you Ben and Eric for the help.