How can I get value of inout parameter from PostgreSQL procedure call?

OpenGL

I have code like this

QString my_str = "call my_proc(null,null);";
QSqlQuery my_query(d);
my_query.exec(my_str);

And it works, it calls the postgresql procedure

procedure my_proc(value int, return_value INOUT int);

But how can I get the value of the return_value parameter?
When I try to get the value from

query.record

it seems the value is always 0.
So I guess I'm missing something important here.

Is there an example of how to do this for Postgresql?

(note: it seems I can not call procedures with bind variables, else I would have tried that).

JonB

@OpenGL said in How can I get value of inout parameter from PostgreSQL procedure call?:

(note: it seems I can not call procedures with bind variables, else I would have tried that).

I don't know anything about PostgreSQL/procedure calls. But as far as I know you must bind to a variable to get an OUT parameter back. So show what you tried for the prepare/bind()?

OpenGL

Prepare/bind does not work with postgres procedures, so I have to do it some other way. And I have no idea how.

SGaist

Hi,

@OpenGL said in How can I get value of inout parameter from PostgreSQL procedure call?:

Prepare/bind does not work with postgres procedures, so I have to do it some other way. And I have no idea how.

Can you provide more information about that ?
Do you have a simple example of procedure that can be tested ?

OpenGL

@SGaist said in How can I get value of inout parameter from PostgreSQL procedure call?:

Hi,

@OpenGL said in How can I get value of inout parameter from PostgreSQL procedure call?:

Prepare/bind does not work with postgres procedures, so I have to do it some other way. And I have no idea how.

Can you provide more information about that ?
Do you have a simple example of procedure that can be tested ?

Hello, sorry for late reply.
I had a discussion about it here https://forum.qt.io/topic/120460/minimal-sql-program-that-fails-what-is-wrong-with-it/2
An minimal example is included there with a procedure that failes to be prepared with the prepare command.

JonB

@OpenGL
I'm not defending this other than as a nasty hack. But if what you say is true, and you are stuck looking for a workaround: you can pass input parameters by interpolating them literally into the call() statement, and you can receive output parameters by returning them via a SELECT statement at the end of a call()ed procedure. Assuming you get a result set back from the call() which the driver can retrieve.