Error occurred at OcilibResultsetFetchFirst: A null Resultset handle has been provided about ocilib

[vrogier]

Hi,

A resultset lifetime is bound to its statement parent object which lifetime is also bound to its parent connection object.

OCILIB C++ object are used as value object but are smart pointers that keeps track internally of these relationships.

When an OCILIB goes out of scope, all of its children are cleaned.

In your executequery function:

• you create a connection
• you create a statement
• you create a resultset
• you return the resultset

Before execute query returns, the destructor of the connection object is invoked. As they is no more reference to it, it cleans it and it leads to free the statement and then the resultset.

You don't really need to use smart pointers as ocilib object are already smart pointers.

You just need to keep references to ocilib objects. You do that by having valid objects.

Your method getconnection could just return a plain connection object instead of shared_ptr (as the connection object is already a smart pointer).

Then your execute query could just return a simple structure with 3 fields : connection object, statement object and resultset object.

In executequery, you create the statement and the resultset.
And return the struct by initializing it with the 3 objects.

And then the results will be valid after returning from execute query.

Vincent

[vrogier]

Current c++ Api objects keep tracks of the C API handles, not C++ objects.

I agree that maintaining a reference to resultset should keep the connection object in memory.

I will make some changes in v4.8 for that.

[MagicXran]

Why the number of results with Resultset::GetCount() is zero ?
But it is valuable after using Next()
the code snippet:

	ocilib::Statement stmt(conn);
	stmt.Execute(sql);
	conn.Commit();
	auto rs = stmt.GetResultset();
	rs.GetCount(); // return 0
	rs.Next();
	rs.Get("xxx"); // is right

[vrogier]

GetCount() returns the number of fetched rows. It is updated after each fetch operation.
There is no way to get row count in advance except using scrollable cursors

[vrogier]

Closing the issue as not a bug and and more related to API usage.