Qt cannot connect Postgresql database different pc

[Joe von Habsburg]

I have a qt application. i am using postgresql as a database. while i have no problems connecting to the database on my own computer, i have problems on another computer. do i need to make any settings in qt or on the computer?

[JonB]

@Joe-von-Habsburg
Presumably you do that by specifying the other computer's name name/IP address for the database to connect to? So you have to make sure (a) the IP address is right, (b) any firewalls let the port through and (c) you have the necessary permissions to access that database and its tables, e.g. your username is acceptable or whatever. What/when do you get an error, what does it say, is it at connection time or when you try to execute a SQL command against a table?

[Joe von Habsburg]

@JonB

my database that's it.

I take release on qtcreater and I add libs (windeployqt --quick) to my computer and run other computer.

I crate database with pgadmin and its name is test. they are same.

    const QString DATABASE_HOST_NAME = "localhost";
    const int DATABASE_HOST_PORT = 5432;
    const QString DATABASE_NAME = "test";
    const QString DATABASE_USER_NAME = "postgres";
    const QString DATABASE_USER_PASSWORD = "postgres";

@jsulm said in Qt cannot connect Postgresql database different pc:

How should this work if you want to connect to SQL server running on another computer?!

I download database to other computer. it will work local

[jsulm]

@Joe-von-Habsburg said in Qt cannot connect Postgresql database different pc:

const QString DATABASE_HOST_NAME = "localhost";

How should this work if you want to connect to SQL server running on another computer?!

[Joe von Habsburg]

@jsulm

I may not have been understood.

1. I create qt app on my computer and work on local. I use postgresql server and I can connect it. I take release on qtcreator. I add libs by windeployqt commond line.

2. I send release file to other computer.

3. I setup postgresql to other computer and it has same properties (databse name, username, user password, port)

But it could not connect. I wonder. do I need to make any additions when I get the release of the application? Or do you have any offer?

[jsulm]

@Joe-von-Habsburg Then please add error handling to your application to get more information about the issue.
https://doc.qt.io/qt-6/qsqldatabase.html#lastError

Also, can you connect to the SQL server using the PostgreSQL client?

[jsulm]

@Joe-von-Habsburg Also, check whether the sql plug-in was loaded: set QT_DEBUG_PLUGINS env variable before starting your app (see https://doc.qt.io/qt-6/debug.html).

[Joe von Habsburg]

@jsulm said in Qt cannot connect Postgresql database different pc:

Also, can you connect to the SQL server using the PostgreSQL client?

yes I can connect by pgadmin and I can do anything (insert, delete, select)

[JonB]

@Joe-von-Habsburg said in Qt cannot connect Postgresql database different pc:

yes I can connect by pgadmin and I can do anything (insert, delete, select)

So I said earlier:

and (c) you have the necessary permissions to access that database and its tables, e.g. your username is acceptable or whatever.

It does not sound like you are passing an acceptable user? If you say it works via pgadmin is that using username postgres as your code does?

In any case please help yourself and us by following @jsulm's

Then please add error handling to your application to get more information about the issue.

You still have not told us which statement it fails on and what the error is (with lastError() for extended information). You should always put in such error handling, both to help you during development and for the end user to report if it goes wrong for whatever reason at runtime/after deployment.

[Joe von Habsburg]

@JonB problem is driver could not be loaded. how can I add it?

[jsulm]

@Joe-von-Habsburg said in Qt cannot connect Postgresql database different pc:

how can I add it?

Did you also deploy the PostgreSQL client library together with your app?
Please post the output of the application after running it with QT_DEBUG_PLUGINS set, else we can only guess...

[Joe von Habsburg]

@jsulm said in Qt cannot connect Postgresql database different pc:

Did you also deploy the PostgreSQL client library together with your app?

How can I do it? I do not know. I know problem is driver but how I am able to add it? if you could help me with this I would appreciate it. what dlls should I add or what should I add to cmake?

@jsulm said in Qt cannot connect Postgresql database different pc:

QT_DEBUG

I can not use Debug. I use release profile on qtcreator

[JonB]

@Joe-von-Habsburg
@jsulm did not ask you about QT_DEBUG or Debug. He asked you to set environment variable QT_DEBUG_PLUGINS (to value 1) before running your program. That will show diagnostic output which you will need to see what is happening/missing. You can look it up in the docs if you wish.

[Joe von Habsburg]

@JonB I do not understand anything. Please could you give more informantion.

Note : app release folder has

I solved the problem :)

I add lib files from Postgresql to release folder

and it works. thank you @jsulm and @JonB