sqlite query not prepared row insterted but empty values - c++

Question

I am writing a function to prepare a sql query and execute it against a sqlite db. I am using a query to insert values in to a table, the query looks like this
"insert into files values (?, ?, ?, ?, ?, 0)";
A row is inserted but all values for text fields are empty except the last field which is 0. The first 5 fields are of type TEXT
// If I hard code a value for value.data() then the row is inserted correctly with my hardcoded data, the exact line is below
status = sqlite3_bind_text(ppStmt, index, /* if I hardcode it works*/ value.data(), -1, SQLITE_STATIC);
The full function is shown below.The list is created on stack by the calller, I am not sure why it is not replacing question marks with my string args, hardcoded ones work though.. no error codes are returned
//db is already open before I call this
void MediaCache::prepareAndExecuteQuery(string query, list<string> args)
{
sqlite3_stmt *ppStmt = 0;
const char **pzTail = 0;
int status = 0;
if( sqlite3_prepare_v2(db, query.data(), query.length(), &ppStmt, pzTail) != SQLITE_OK )
{
string error = sqlite3_errmsg(db);
//throw an exception
}
if(ppStmt)
{
list<string>::iterator current = args.begin();
int index = 1;
for(current = args.begin() ; current != args.end(); current++)
{
string value = *current;
status = sqlite3_bind_text(ppStmt, index, value.data(), -1, SQLITE_STATIC);
if(status != SQLITE_OK)
{
//log error;
}
index++;
}
status = sqlite3_step(ppStmt);
status = sqlite3_finalize(ppStmt);
//sqlite3_exec(db, "COMMIT", NULL, NULL, NULL);
}
else
{
//ppStmt is null
//throw an exception
}
}

Answer 1

I suspect the problem is here:
string value = *current;
status = sqlite3_bind_text(ppStmt, index, value.data(), -1, SQLITE_STATIC);
In this case value goes out of scope before the execution of the statement takes place. So the pointers given to sqlite3_bind_text are no longer valid. To "fix" that, you could use SQLITE_TRANSIENT, which would force the library to make its own copy of the data before returning.
Also, if you are not using C++11, I don't believe string::data() is guaranteed to be NULL terminated in which case the -1 parameter could be incorrect. It should maybe be value.length() instead.