我想转换 本例 在Delphi代码中,我的问题是在获取" Associators of " 语句查询的结果。
procedure TUSB.GetInfo;
var
WMIService : OLEVariant;
DItems, PItems, LItems, VItems: OLEVariant;
Drive, Partition, Logical, Volume : OLEVariant;
Drives, Partitions, Logicals, Volumes : IEnumVARIANT;
IValue : LongWord;
begin
WMIService := GetWMIObject('winmgmts:\\localhost\root\cimv2');
DItems := WMIService.ExecQuery('select DeviceID, Model from Win32_DiskDrive where InterfaceType='+QuotedStr('USB'));
Drives := IUnKnown(DItems._NewEnum) as IEnumVARIANT;
Drives.Next(1, Drive, IValue);
DeviceID := Drive.Properties_.Item('DeviceID', 0);
PItems := WMIService.ExecQuery('associators of {{Win32_DiskDrive.DeviceID='+QuotedStr(DeviceID)+'}} where AssocClass = Win32_DiskDriveToDiskPartition');
Partitions := IUnKnown(PItems._NewEnum) as IEnumVARIANT;
Partitions.Next(1, Partition, IValue);
**PDeviceID := Partition.Properties_.Item('DeviceID', 0);**
...
end;
在标有2颗星的那一行! 我得到了一个错误:" 无效变量操作 "而在上面的相同代码中,没有任何错误!
问题出在哪里?在" Associators of " 语句或...!
非常感谢...
在没有看到所有相关代码和声明的情况下,很难判断。当你写。
Partitions.Next(1, Partition, IValue);
你应该检查一下你是否真的得到了你想要的东西。Partition
. 而且更普遍的是,为了调试,你应该总是打破你的复合语句来测试每个中间步骤。
Partition.Properties_ // is it correct? how many items?
Partition.Properties_.Item('DeviceID', 0) // if not OK try to iterate through all items
感谢Francois...
"在没有看到所有相关代码和声明的情况下,很难说。"
但没有更多的相关代码! , 我已经改变了下面的代码 :
procedure TUSBItem.GetInfo;
var
WMIService : OLEVariant;
DItems, PItems, LItems, VItems: OLEVariant;
Drive, Partition, Logical, Volume : OLEVariant;
Drives, Partitions, Logicals, Volumes : IEnumVARIANT;
IValue : LongWord;
begin
WMIService := GetWMIObject('winmgmts:\\localhost\root\cimv2');
DItems := WMIService.ExecQuery('select DeviceID, Model from Win32_DiskDrive where InterfaceType='+QuotedStr('USB'));
Drives := IUnKnown(DItems._NewEnum) as IEnumVARIANT;
while Drives.Next(1, Drive, IValue) = S_OK do
begin
DeviceID := Drive.Properties_.Item('DeviceID', 0);
PItems := WMIService.ExecQuery('associators of {{Win32_DiskDrive.DeviceID='+QuotedStr(DeviceID)+'}} where AssocClass = Win32_DiskDriveToDiskPartition');
Partitions := IUnKnown(PItems._NewEnum) as IEnumVARIANT;
if Partitions.Next(1, Partition, IValue) = S_OK then
begin
if not VarIsNull(Partition) then
PDeviceID := Partition.Properties_.Item('DeviceID', 0);
end;
...
end;
...
end;
在 而 循环 , 对于每个驱动器在Drives枚举变量 , 我得到一个 "DeviceID" , 我应该传递 "DeviceID" 到 " Associators of " 语句,以获得与驱动器相关联的分区列表 "DeviceID" 作为查询结果... ...
在下一行 , 我把分区中的项目作为一个IEnumVARIANT , 接下来我检查是否把分区的第一个元素在分区中返回 " S_OK " ( 成功 !),然后我检查分区,如果它不是。t null then i get one of it
命名为 "DeviceID "的项目,但在这一行,我得到了一个错误的消息:"无效变量操作"
有相同的方法来获取驱动器的DeviceID和分区的DeviceID,但当我想获取分区的DeviceID时,我得到了一个错误,他们之间有一个不同的,它的WMI查询,我想问题是,但我不知道!我想这是我的问题。
这里有一些有用的句子。
" 但是,在编写框架提供者时,你应该记住以下几点。
* Make sure you support standard queries in your association class, especially queries where the reference properties are used in a WHERE clause. For more information, see CFrameworkQuery::GetValuesForProp.
* In your association class support, when you check to see if the endpoints exist, ensure you use the CWbemProviderGlue::GetInstanceKeysByPath or CWbemProviderGlue::GetInstancePropertiesByPath methods.
These methods allow the endpoints to skip populating expensive or unneeded properties.
* Make sure any association endpoint classes support per-property Get methods. For more information, see Supporting Partial-Instance Operations. For more information about the query parameter, see CFrameworkQuery. **"**
因为这个解释!我认为问题出在Path上! , 意味着我应该把我的目标(这里是Partition)给WMIService对象以获得结果! , 我认为问题出在Path上。, 有所帮助 但我完全不明白!!!
当然,在 资料页 我转换它,没有任何解释的路径...!
非常感谢...