Esempio delle proprietà Description, HelpContext, HelpFile, NativeError, Number, Source e SQLState (VC++)

In questo esempio viene attivato un errore, viene intercettato e vengono visualizzate le proprietà Description, HelpContext, HelpFile, NativeError, Number, Source e SQLState dell'oggetto Error risultante.

// BeginDescriptionCpp.cpp  
// compile with: /EHsc  
#import "msado15.dll" no_namespace rename("EOF", "EndOfFile")  
  
// Function declarations  
inline void TESTHR(HRESULT x) {if FAILED(x) _com_issue_error(x);};  
void DescriptionX();  
void PrintProviderError(_ConnectionPtr pConnection);  
void PrintComError(_com_error &e);  
  
int main() {  
   if (FAILED(::CoInitialize(NULL)))  
      return -1;  
  
   DescriptionX();  
   ::CoUninitialize();  
}  
  
void DescriptionX() {  
   // Define ADO object pointers. Initialize pointers on define. These are in the ADODB::  namespace  
   _ConnectionPtr pConnection = NULL;  
   ErrorPtr errorLoop = NULL;  
  
   // Define Other Variables  
   HRESULT hr = S_OK;  
  
   try {  
      // Intentionally trigger an error.  open connection  
      TESTHR(pConnection.CreateInstance(__uuidof(Connection)));  
  
      if (FAILED(hr = pConnection->Open("Nothing", "", "", adConnectUnspecified))) {  
         _com_issue_error(hr);  
         exit(1);  
      }  
  
      // Cleanup object before exit.  
      pConnection->Close();  
   }  
   catch(_com_error) {  
      // Pass a connection pointer.  
      PrintProviderError(pConnection);  
   }  
}  
  
void PrintProviderError(_ConnectionPtr pConnection) {  
   // Define Other Variables  
   HRESULT hr = S_OK;  
   _bstr_t strError;  
   ErrorPtr pErr = NULL;  
  
   try {  
      // Enumerate Errors collection and display properties of each Error object.  
      long nCount = pConnection->Errors->Count;  
  
      // Collection ranges from 0 to nCount - 1.  
      for ( long i = 0 ; i < nCount ; i++ ) {  
         pErr = pConnection->Errors->GetItem(i);  
         printf("Error #%d\n", pErr->Number);  
         printf(" %s\n", (LPCSTR)pErr->Description);  
         printf(" (Source: %s)\n", (LPCSTR)pErr->Source);  
         printf(" (SQL State: %s)\n", (LPCSTR)pErr->SQLState);  
         printf(" (NativeError: %d)\n", (LPCSTR)pErr->NativeError);  
  
         if ((LPCSTR)pErr->GetHelpFile() == NULL)  
            printf("\tNo Help file available\n");  
         else {  
            printf("\t(HelpFile: %s\n)" ,pErr->HelpFile);  
            printf("\t(HelpContext: %s\n)" , pErr->HelpContext);  
         }  
      }  
   }  
  
   catch(_com_error &e) {  
      // Notify the user of errors if any.  
      PrintComError(e);  
   }  
}  
  
void PrintComError(_com_error &e) {  
   // Notify the user of errors if any.  
   _bstr_t bstrSource(e.Source());  
   _bstr_t bstrDescription(e.Description());  
  
   // Print Com errors.  
   printf("Error\n");  
   printf("\tCode = %08lx\n", e.Error());  
   printf("\tCode meaning = %s", e.ErrorMessage());  
   printf("\tSource = %s\n", (LPCSTR) bstrSource);  
   printf("\tDescription = %s\n", (LPCSTR) bstrDescription);  
}  

Vedere anche

Proprietà Description
Oggetto Error
Proprietà HelpContext e HelpFile
Proprietà HelpContext e HelpFile
Proprietà NativeError (ADO)
Proprietà Number (ADO)
Proprietà Source (Error - ADO)
Proprietà SQLState