CODEWITHSUNDEEP
c#wmi
Tar
Tar

Reputation: 9015

How to call ManagementBaseObject methods or get a ManagementObject?

TL/DR:

The main issue is this: I get a ManagementBaseObject as returned value. But I cannot call its methods, as it doesn't have the InvokeMethod() member, like ManagementObject has. So how do I call its member-methods?

elaboration:

I open a BcdStore object:

var bcdCls = new ManagementClass(@"root\WMI", "BcdStore", null); // OpenStore is a static method
var methodParams = bcdCls.GetMethodParameters("OpenStore");
methodParams["file"] = ""; // the default store
var results = bcdCls.InvokeMethod("OpenStore", methodParams, null);
Assert.IsNotNull(results);
var store = results["store"] as ManagementBaseObject;
Assert.IsNotNull(store);

But this object is useless:

// unfortunately, it is not a ManagementObject, so no InvokeMethod() is possible :-(
Assert.IsNull(store as ManagementObject);
store.InvokeMethod("EnumerateObjects", new object[] { 0 }); // Compilation error!
// ManagementBaseObject doesn't have an InvokeMethod member method!

Upvotes: 2

Views: 5588

Answers (1)

Yoh Deadfall
Yoh Deadfall

Reputation: 2781

Probably it's a bug, because PropertyData always returns ManagementBaseObject if Type's value is CimType.Object (source). The return value of InvokeMethod is also ManagementBaseObject(source), except when ManagementOperationObserver is used.

Example without an observer:

// result is ManagementBaseObject
// result["__GENUS"] == 2
var result = bcdCls.InvokeMethod("OpenStore", methodParams, null);

Example with an observer:

var observer = new ManagementOperationObserver();

observer.ObjectReady += ObjectReady;
bcd.InvokeMethod(observer, "OpenStore", methodParams, null);

void ObjectReady(object sender, ObjectReadyEventArgs e)
{
    // e.NewObject is ManagementObject
    // e.NewObject["__GENUS"] == 2
}

In the second snippet we have a ManagementObject, because the ManagementBaseObject.GetBaseObject method is used internally (source). So you can report to Microsoft.

And finally, workaround:

var bcd = new ManagementClass(@"root\WMI", "BcdStore", null);
var openStoreParams = bcd.GetMethodParameters("OpenStore");

openStoreParams["File"] = "";

var openStoreResult = bcd.InvokeMethod("OpenStore", openStoreParams, null);
var openedStore = (ManagementObject)typeof(ManagementBaseObject)
    .GetMethod("GetBaseObject", BindingFlags.Static | BindingFlags.NonPublic)
    .Invoke(
        null,
        new object[]
        {
            typeof(ManagementBaseObject)
                .GetField("_wbemObject", BindingFlags.Instance | BindingFlags.NonPublic)
                .GetValue(openStoreResult["Store"]),
            bcd.Scope
        }
    );
var enumObjectsParams = openedStore.GetMethodParameters("EnumerateObjects");

enumObjectsParams["Type"] = 0;

var enumObjectsResult = openedStore.InvokeMethod("EnumerateObjects", enumObjectsParams, null);
var enumObjects = (ManagementBaseObject[])enumObjectsResult["Objects"];

foreach (var enumObject in enumObjects)
{
    // Do something
}

Upvotes: 2

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