IModelKeyReference::GetKey method (dbgmodel.h)

Article
02/22/2024

The GetKey method on a key reference behaves as the GetKey method on IModelObject would. It returns the value of the underlying key and any metadata associated with the key. If the value of the key happens to be a property accessor, this will return the property accessor (IModelPropertyAccessor) boxed into an IModelObject. This method will not call the underlying GetValue or SetValue methods on the property accessor.

Syntax

HRESULT GetKey(
  _COM_Errorptr_opt_ IModelObject **object,
  IKeyStore                       **metadata
);

Parameters

object

The value of the key will be returned here.

metadata

Optional metadata which is associated with the key will be returned here.

Return value

This method returns HRESULT that indicates success or failure.

Remarks

Code Sample

ComPtr<IModelObject> spObject; /* get an object */

ComPtr<IModelKeyReference> spKeyRef;
if (SUCCEEDED(spObject->GetKeyReference(L"Id", &spKeyRef, nullptr)))
{
    ComPtr<IModelObject> spKey;
    if (SUCCEEDED(spKeyRef->GetKey(&spKey, nullptr)))
    {
        // spKey contains the equivalent of spObject->GetKey(L"Id", &spKey, nullptr)
        // This may be a property accessor since this was not a GetKeyValue.  
        // Check and fetch.  Note that GetKeyValue would do this for you.
        ModelObjectKind kind;
        if (SUCCEEDED(spKey->GetKind(&kind)))
        {
            if (kind == ObjectPropertyAccessor)
            {
                VARIANT vtProp;
                if (SUCCEEDED(spKey->GetIntrinsicValue(&vtProp)))
                {
                    // We are guaranteed *in-process* that the IUnknown is 
                    // an IModelPropertyAccessor via the ObjectPropertyAccessor
                    IModelPropertyAccessor *pProperty =
                        static_cast<IModelPropertyAccessor *>(vtProp.punkVal);
                    
                    // In order to fetch, we need to know the context object and 
                    // the key name.  Fetch it from the key reference.
                    ComPtr<IModelObject> spContextObject;
                    if (SUCCEEDED(spKeyRef->GetContextObject(&spContextObject)))
                    {
                        BSTR keyName;
                        if (SUCCEEDED(spKeyRef->GetName(&keyName)))
                        {
                            ComPtr<IModelObject> spKeyValue; 
                            if (SUCCEEDED(pProperty->GetValue(keyName,
                                                              spContextObject.Get(),
                                                              &spKeyValue)))
                            {
                                // spKeyValue contains the value of the "Id" key.
                            }

                            SysFreeString(keyName);
                        }
                    }

                    VariantFree(&vtProp);
                }
            }
            else
            {
                // spKey contains the value of the "Id" key.
            }
        }
    }
}

Requirements

Requirement	Value
Header	dbgmodel.h