ObjectDatabase++ Documentation

Delevopers ObjectDatabase++ API Read Object

ReadObject

ReadObject finds an object matching the search values, reads the object into the table's buffers and locks the object, this operation does not log or back-up the object.

unsigned int ReadObject (
	unsigned int tableID,
	__int64 objectID,
	CODBPP::Object *object = NULL
);
unsigned int ReadObject (
	unsigned int tableID,
	__int64 objectID,
	CODBPP::Mode operation,
	CODBPP::Object *object = NULL
);
unsigned int ReadObject (
	unsigned int tableID,
	CODBPP::Mode operation,
	CODBPP::Object *object = NULL,
	unsigned int index = 0,
	const void *key = NULL,
	unsigned int *matchingRow = NULL
);

Parameters

tableID	The table ID defining the table's handle.
objectID	The object ID defining the object's handle when using the shorthand version.
operation	Valid operations only.
object	For the returned object addresses.
index	The index value, 0 for object ID hash index, 1 for the first defined index.
key	The key value used in any find comparison.
matchingRow	Used to identify which row of a sub-table field, within the current object has the matching multi-entry index value.

Return Values

If the method succeeds, the return value is zero else see error codes for more details.

Remarks

ReadObject can be used before DeleteObject or RewriteObject to enable 2-phased commit protocols.

ReadObject will attempt to lock twenty times longer if the object is above the transaction’s high water mark, if the object is below the mark than ReadObject will return an error if unable to gain object lock.

ReadObject will allow the operation of NO_LOCK if the object is un-important to the finial results of the transaction and locking would only block other transactions from completing.

ReadObject will allow the operation of NO_WAIT and SHORT_WAIT if the object is known to be locked and there is little need to wait the entire timeout period before returning CODBPP::UNABLE_TO_LOCK_OBJECT.

Example Use

CODBPP::Object object;
struct FixedObject{
   int First;
   double Second;
} *fixedObject;
char16_t *userName = _T"UserName", message, buffer[128];
if((error = database.BeginTransaction()) == NO_ERROR){
   if((error = database.OpenTable(1)) == NO_ERROR){
      if((error = database.ReadObject(1,CODBPP::EQUALTO,&object,1,userName)) == NO_ERROR){
         fixedObject = (struct FixedObject*)object.fixed;
         swprintf(buffer,_T"First = %d, Second = %g", fixedObject->First, fixedObject->Second);
         MessageBox(buffer);
      }
   }
}
if(error && database.GetErrorMessage(&message) == NO_ERROR)
   MessageBox(message);
database.EndTransaction();

Also See

AddObject, NewObject, DeleteObject, RestoreObject, RewriteObject, SearchIndex