Skip to content
  • Categories
  • Recent
  • Tags
  • Popular
  • Users
  • Groups
  • Search
  • Get Qt Extensions
  • Unsolved
Collapse
Brand Logo
  1. Home
  2. Qt Development
  3. General and Desktop
  4. QSqlTableModel() empty on Ubuntu but works on Windows ?
QtWS25 Last Chance

QSqlTableModel() empty on Ubuntu but works on Windows ?

Scheduled Pinned Locked Moved Solved General and Desktop
qsqltablemodelqsqldatabasepostgresql
41 Posts 4 Posters 8.4k Views
  • Oldest to Newest
  • Newest to Oldest
  • Most Votes
Reply
  • Reply as topic
Log in to reply
This topic has been deleted. Only users with topic management privileges can see it.
  • JonBJ JonB

    @R-P-H said in QSqlTableModel() empty on Ubuntu but works on Windows ?:

    QSqlDatabasePrivate::database: unable to open database: "FATAL: role "(removed)" does not exist\nQPSQL: Unable to connect"

    I'm not an expert, but you can Google for PSQL FATAL role and get a fair number of hits about this "permission" issue, e.g. https://stackoverflow.com/questions/11919391/postgresql-error-fatal-role-username-does-not-exist.

    R Offline
    R Offline
    R-P-H
    wrote on last edited by
    #17

    @JonB said in QSqlTableModel() empty on Ubuntu but works on Windows ?:

    @R-P-H said in QSqlTableModel() empty on Ubuntu but works on Windows ?:

    QSqlDatabasePrivate::database: unable to open database: "FATAL: role "(removed)" does not exist\nQPSQL: Unable to connect"

    I'm not an expert, but you can Google for PSQL FATAL role and get a fair number of hits about this "permission" issue, e.g. https://stackoverflow.com/questions/11919391/postgresql-error-fatal-role-username-does-not-exist.

    No, that is caused by the following line of code:

    QSqlDatabase::addDatabase("QPSQL");

    It is because at this point in the code I have not yet set the details for accessing the database. I am just loading the driver on startup. So this "error" is not the issue.

    1 Reply Last reply
    0
    • SGaistS Offline
      SGaistS Offline
      SGaist
      Lifetime Qt Champion
      wrote on last edited by
      #18

      @R-P-H said in QSqlTableModel() empty on Ubuntu but works on Windows ?:

      FATAL: role "(removed)" does not exist\nQPSQL: Unable to connect

      Does removed match postgres ? If not, how did you create the database in the first place ? Under which role did you create it ?

      Interested in AI ? www.idiap.ch
      Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

      R 1 Reply Last reply
      0
      • SGaistS SGaist

        @R-P-H said in QSqlTableModel() empty on Ubuntu but works on Windows ?:

        FATAL: role "(removed)" does not exist\nQPSQL: Unable to connect

        Does removed match postgres ? If not, how did you create the database in the first place ? Under which role did you create it ?

        R Offline
        R Offline
        R-P-H
        wrote on last edited by R-P-H
        #19

        @SGaist No. The database is already created with a specific role that has access.

        /*Somewhere in beginning of program*/
        QSqlDatabase::addDatabase("QPSQL"); //Only called once
        
        /* Later in program when accessing the database */
        QSqlDatabase db = QSqlDatabase::database();
        db.setHostName("localhost");
        db.setPort(5432);
        db.setDatabaseName("test_db");
        db.setUserName("test_user");
        db.setPassword("test_pass");
        

        The role with access to the db and table is "test_user", created using pgadmin4 or psql.

        1 Reply Last reply
        0
        • R R-P-H

          Hi, I am trying to populate a QSqlTableModel() using a table in my Postgresql database and display it in a QTableView. Here is the first part of the code:

          QSqlDatabase db = QSqlDatabase::addDatabase("QPSQL");
          db.setHostName("localhost");
          db.setPort(5432);
          db.setDatabaseName("test_db");
          db.setUserName("test_user");
          db.setPassword("test_pass");
          bool ok = db.open();
          QSqlTableModel *model = new QSqlTableModel(nullptr, db);
          if (ok){
              model->setTable("my_table_name_here");
              model->select();
          }
          

          On Windows, this works perfectly and QTableView is populated.

          However, when testing on Ubuntu 16.04 LTS the QTableView is empty. I checked the output of model->rowCount(); and it returns '0'.

          A few things to note:

          • Both Operating Systems are accessing the same database using the same credentials.
          • On Ubuntu, using a standard QSqlQuery works perfectly in accessing data from the very same database in the same application.
          • There are no errors in opening the database or anything else related.

          This really has me stumped. Why is it not working on Ubuntu ? Thanks.

          VRoninV Offline
          VRoninV Offline
          VRonin
          wrote on last edited by
          #20

          @R-P-H said in QSqlTableModel() empty on Ubuntu but works on Windows ?:

          On Ubuntu, using a standard QSqlQuery works perfectly in accessing data from the very same database in the same application.

          This is what baffles me. If the problem was in the db driver, the query should fail too. I'm very confused about what's going on...

          "La mort n'est rien, mais vivre vaincu et sans gloire, c'est mourir tous les jours"
          ~Napoleon Bonaparte

          On a crusade to banish setIndexWidget() from the holy land of Qt

          JonBJ R 2 Replies Last reply
          0
          • VRoninV VRonin

            @R-P-H said in QSqlTableModel() empty on Ubuntu but works on Windows ?:

            On Ubuntu, using a standard QSqlQuery works perfectly in accessing data from the very same database in the same application.

            This is what baffles me. If the problem was in the db driver, the query should fail too. I'm very confused about what's going on...

            JonBJ Offline
            JonBJ Offline
            JonB
            wrote on last edited by JonB
            #21

            @VRonin
            @R-P-H has already said:

            QSqlDatabasePrivate::database: unable to open database: "FATAL: role "(removed)" does not exist\nQPSQL: Unable to connect"
            No, that is caused by the following line of code:

            QSqlDatabase::addDatabase("QPSQL");
            On Ubuntu, using a standard QSqlQuery works perfectly in accessing data from the very same database in the same application.

            So we seem to have an error at add database stage, and then QSqlQuery works fine but not QSqlTableModel. But I think the OP says this does not matter (though it would worry me).

            check the return value of model->select(); and if it returns false use model->lastError() to diagnose what's going wrong

            QSqlError("", "Unable to find table logs", "")

            Should the OP try printing out what QString QSqlTableModel::selectStatement() const returns? And/or whatever is in QSqlQuery QSqlQueryModel::query() const?

            R 1 Reply Last reply
            0
            • VRoninV VRonin

              @R-P-H said in QSqlTableModel() empty on Ubuntu but works on Windows ?:

              On Ubuntu, using a standard QSqlQuery works perfectly in accessing data from the very same database in the same application.

              This is what baffles me. If the problem was in the db driver, the query should fail too. I'm very confused about what's going on...

              R Offline
              R Offline
              R-P-H
              wrote on last edited by
              #22

              @VRonin said in QSqlTableModel() empty on Ubuntu but works on Windows ?:

              @R-P-H said in QSqlTableModel() empty on Ubuntu but works on Windows ?:

              On Ubuntu, using a standard QSqlQuery works perfectly in accessing data from the very same database in the same application.

              This is what baffles me. If the problem was in the db driver, the query should fail too. I'm very confused about what's going on...

              Yes, it makes no sense.

              1 Reply Last reply
              0
              • JonBJ JonB

                @VRonin
                @R-P-H has already said:

                QSqlDatabasePrivate::database: unable to open database: "FATAL: role "(removed)" does not exist\nQPSQL: Unable to connect"
                No, that is caused by the following line of code:

                QSqlDatabase::addDatabase("QPSQL");
                On Ubuntu, using a standard QSqlQuery works perfectly in accessing data from the very same database in the same application.

                So we seem to have an error at add database stage, and then QSqlQuery works fine but not QSqlTableModel. But I think the OP says this does not matter (though it would worry me).

                check the return value of model->select(); and if it returns false use model->lastError() to diagnose what's going wrong

                QSqlError("", "Unable to find table logs", "")

                Should the OP try printing out what QString QSqlTableModel::selectStatement() const returns? And/or whatever is in QSqlQuery QSqlQueryModel::query() const?

                R Offline
                R Offline
                R-P-H
                wrote on last edited by
                #23

                @JonB said in QSqlTableModel() empty on Ubuntu but works on Windows ?:

                @VRonin
                @R-P-H has already said:

                QSqlDatabasePrivate::database: unable to open database: "FATAL: role "(removed)" does not exist\nQPSQL: Unable to connect"
                No, that is caused by the following line of code:

                QSqlDatabase::addDatabase("QPSQL");
                On Ubuntu, using a standard QSqlQuery works perfectly in accessing data from the very same database in the same application.

                So we seem to have an error at add database stage, and then QSqlQuery works fine but not QSqlTableModel. But I think the OP says this does not matter (though it would worry me).

                Even if I change the code to this it still doesn't work (and the error disappears).

                QSqlDatabase db = QSqlDatabase::addDatabase("QPSQL");
                db.setHostName("localhost");
                db.setPort(5432);
                db.setDatabaseName("test_db");
                db.setUserName("test_user");
                db.setPassword("test_pass");
                
                JonBJ 1 Reply Last reply
                0
                • R R-P-H

                  @JonB said in QSqlTableModel() empty on Ubuntu but works on Windows ?:

                  @VRonin
                  @R-P-H has already said:

                  QSqlDatabasePrivate::database: unable to open database: "FATAL: role "(removed)" does not exist\nQPSQL: Unable to connect"
                  No, that is caused by the following line of code:

                  QSqlDatabase::addDatabase("QPSQL");
                  On Ubuntu, using a standard QSqlQuery works perfectly in accessing data from the very same database in the same application.

                  So we seem to have an error at add database stage, and then QSqlQuery works fine but not QSqlTableModel. But I think the OP says this does not matter (though it would worry me).

                  Even if I change the code to this it still doesn't work (and the error disappears).

                  QSqlDatabase db = QSqlDatabase::addDatabase("QPSQL");
                  db.setHostName("localhost");
                  db.setPort(5432);
                  db.setDatabaseName("test_db");
                  db.setUserName("test_user");
                  db.setPassword("test_pass");
                  
                  JonBJ Offline
                  JonBJ Offline
                  JonB
                  wrote on last edited by
                  #24

                  @R-P-H
                  Point taken.

                  I did suggest

                  Should the OP try printing out what QString QSqlTableModel::selectStatement() const returns? And/or whatever is in QSqlQuery QSqlQueryModel::query() const?

                  ?

                  R 1 Reply Last reply
                  0
                  • JonBJ JonB

                    @R-P-H
                    Point taken.

                    I did suggest

                    Should the OP try printing out what QString QSqlTableModel::selectStatement() const returns? And/or whatever is in QSqlQuery QSqlQueryModel::query() const?

                    ?

                    R Offline
                    R Offline
                    R-P-H
                    wrote on last edited by
                    #25

                    @JonB said in QSqlTableModel() empty on Ubuntu but works on Windows ?:

                    @R-P-H
                    Point taken.

                    I did suggest

                    Should the OP try printing out what QString QSqlTableModel::selectStatement() const returns? And/or whatever is in QSqlQuery QSqlQueryModel::query() const?

                    ?

                    How do I call these functions because they are protected ?

                    JonBJ 1 Reply Last reply
                    0
                    • R R-P-H

                      @JonB said in QSqlTableModel() empty on Ubuntu but works on Windows ?:

                      @R-P-H
                      Point taken.

                      I did suggest

                      Should the OP try printing out what QString QSqlTableModel::selectStatement() const returns? And/or whatever is in QSqlQuery QSqlQueryModel::query() const?

                      ?

                      How do I call these functions because they are protected ?

                      JonBJ Offline
                      JonBJ Offline
                      JonB
                      wrote on last edited by JonB
                      #26

                      @R-P-H
                      You sub-class from QSqlDatabaseQSqlTableModel. Personally I would always do that anyway, precisely for this reason --- you never know what you may find you need to add/alter from the supplied QSqlDatabaseQSqlTableModel. (I do this for all QWidgets too, but that's another matter.)

                      R 1 Reply Last reply
                      0
                      • JonBJ JonB

                        @R-P-H
                        You sub-class from QSqlDatabaseQSqlTableModel. Personally I would always do that anyway, precisely for this reason --- you never know what you may find you need to add/alter from the supplied QSqlDatabaseQSqlTableModel. (I do this for all QWidgets too, but that's another matter.)

                        R Offline
                        R Offline
                        R-P-H
                        wrote on last edited by
                        #27

                        @JonB said in QSqlTableModel() empty on Ubuntu but works on Windows ?:

                        @R-P-H
                        You sub-class from QSqlDatabase. Personally I would always do that anyway, precisely for this reason --- you never know what you may find you need to add/alter from the supplied QSqlDatabase. (I do this for all QWidgets too, but that's another matter.)

                        Can you please provide an example ?

                        JonBJ 1 Reply Last reply
                        0
                        • R R-P-H

                          @JonB said in QSqlTableModel() empty on Ubuntu but works on Windows ?:

                          @R-P-H
                          You sub-class from QSqlDatabase. Personally I would always do that anyway, precisely for this reason --- you never know what you may find you need to add/alter from the supplied QSqlDatabase. (I do this for all QWidgets too, but that's another matter.)

                          Can you please provide an example ?

                          JonBJ Offline
                          JonBJ Offline
                          JonB
                          wrote on last edited by JonB
                          #28

                          @R-P-H
                          Of how to sub-class in C++? It's just basic C++.

                          I see @SGaist offered this 7 years ago: https://forum.qt.io/topic/30562/example-of-subclassing-qsqltablemodel/2. You'll want something like:

                          // mytablemodel.h
                          class MyTableModel : public QSqlTableModel
                          {
                          public:
                          explicit MyTableModel(QObject * parent = 0, QSqlDatabase db = QSqlDatabase() ); // the same arguments as QSqlTableModel
                          
                          protected:
                          virtual QString selectStatement() const;
                          };
                          
                          // mytablemodel.cpp
                          MyTableModel::MyTableModel(QObject * parent, QSqlDatabase db) :
                          QSqlTableModel(parent, db)
                          {
                          // the rest of your code
                          }
                          
                          QString MyTableModel::selectStatement() const
                          {
                              QString ss = QSqlTableModel::selectStatement();
                              qDebug() << ss;
                              return ss;
                          }
                          

                          I don't think QSqlQuery QSqlQueryModel::query() const is virtual, so you can't override it; nor is it protected, it's public, so just call it if you need to access it.

                          R 1 Reply Last reply
                          0
                          • JonBJ JonB

                            @R-P-H
                            Of how to sub-class in C++? It's just basic C++.

                            I see @SGaist offered this 7 years ago: https://forum.qt.io/topic/30562/example-of-subclassing-qsqltablemodel/2. You'll want something like:

                            // mytablemodel.h
                            class MyTableModel : public QSqlTableModel
                            {
                            public:
                            explicit MyTableModel(QObject * parent = 0, QSqlDatabase db = QSqlDatabase() ); // the same arguments as QSqlTableModel
                            
                            protected:
                            virtual QString selectStatement() const;
                            };
                            
                            // mytablemodel.cpp
                            MyTableModel::MyTableModel(QObject * parent, QSqlDatabase db) :
                            QSqlTableModel(parent, db)
                            {
                            // the rest of your code
                            }
                            
                            QString MyTableModel::selectStatement() const
                            {
                                QString ss = QSqlTableModel::selectStatement();
                                qDebug() << ss;
                                return ss;
                            }
                            

                            I don't think QSqlQuery QSqlQueryModel::query() const is virtual, so you can't override it; nor is it protected, it's public, so just call it if you need to access it.

                            R Offline
                            R Offline
                            R-P-H
                            wrote on last edited by
                            #29

                            @JonB I'm not quite sure how to implement this correctly. I have a class that deals with all database related stuff. Inside that class I have a function that generates the QSqlTableModel using the code you've already seen.

                            Now obviously if I create another class for MyTableModel, include it and create model using MyTableModel *model = new MyTableModel(nullptr, db); instead I still get a protected function error when calling its selectStatement() member.

                            What would be the correct way of testing this ? Thanks.

                            JonBJ 1 Reply Last reply
                            0
                            • R R-P-H

                              @JonB I'm not quite sure how to implement this correctly. I have a class that deals with all database related stuff. Inside that class I have a function that generates the QSqlTableModel using the code you've already seen.

                              Now obviously if I create another class for MyTableModel, include it and create model using MyTableModel *model = new MyTableModel(nullptr, db); instead I still get a protected function error when calling its selectStatement() member.

                              What would be the correct way of testing this ? Thanks.

                              JonBJ Offline
                              JonBJ Offline
                              JonB
                              wrote on last edited by JonB
                              #30

                              @R-P-H

                              Inside that class I have a function that generates the QSqlTableModel

                              You don't want to directly create a QSqlTableModel anywhere, you want it now to create a MyTableModel. E.g if you currently have a new QSqlTableModel somewhere it now goes new MyTableModel. This is basic C++ sub-classing, I don't know whether you're confused over that.

                              include it and create model using MyTableModel *model = new MyTableModel(nullptr, db); instead I still get a protected function error when calling its selectStatement() member.

                              Assuming you've got the first bit right, you still cannot call a protected method on an instance from outside of the MyTableModel class code, that's what protected is all about. You will need something like the definition I showed you of QString MyTableModel::selectStatement() const. You can either then write another public method in MyTableModel which calls it and the outside world can go via that public method, or (as I do) override all the methods in MyTableModel which do queries, updates etc. and have them print it out. It takes a few minutes to write these override functions, but once you have them from then on it's a lot easier to see what's going on, do logging, handle any errors etc. from the QSql... classes you use.

                              R 1 Reply Last reply
                              1
                              • JonBJ JonB

                                @R-P-H

                                Inside that class I have a function that generates the QSqlTableModel

                                You don't want to directly create a QSqlTableModel anywhere, you want it now to create a MyTableModel. E.g if you currently have a new QSqlTableModel somewhere it now goes new MyTableModel. This is basic C++ sub-classing, I don't know whether you're confused over that.

                                include it and create model using MyTableModel *model = new MyTableModel(nullptr, db); instead I still get a protected function error when calling its selectStatement() member.

                                Assuming you've got the first bit right, you still cannot call a protected method on an instance from outside of the MyTableModel class code, that's what protected is all about. You will need something like the definition I showed you of QString MyTableModel::selectStatement() const. You can either then write another public method in MyTableModel which calls it and the outside world can go via that public method, or (as I do) override all the methods in MyTableModel which do queries, updates etc. and have them print it out. It takes a few minutes to write these override functions, but once you have them from then on it's a lot easier to see what's going on, do logging, handle any errors etc. from the QSql... classes you use.

                                R Offline
                                R Offline
                                R-P-H
                                wrote on last edited by
                                #31

                                @JonB The result of selectStatement() is " ".

                                1 Reply Last reply
                                0
                                • SGaistS Offline
                                  SGaistS Offline
                                  SGaist
                                  Lifetime Qt Champion
                                  wrote on last edited by
                                  #32

                                  Would you be able to provide a small step by step guide to reproduce your test database ? Meaning the command you are currently using on your Linux machine to create the role and the database.

                                  Interested in AI ? www.idiap.ch
                                  Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

                                  R 1 Reply Last reply
                                  0
                                  • SGaistS SGaist

                                    Would you be able to provide a small step by step guide to reproduce your test database ? Meaning the command you are currently using on your Linux machine to create the role and the database.

                                    R Offline
                                    R Offline
                                    R-P-H
                                    wrote on last edited by R-P-H
                                    #33

                                    @SGaist Hi, I just use psql to create the database/table/user.

                                    CREATE DATABASE my_db
                                        WITH 
                                        OWNER = postgres
                                        ENCODING = 'UTF8'
                                        TABLESPACE = pg_default
                                        CONNECTION LIMIT = -1;
                                    
                                    CREATE ROLE my_user WITH
                                      LOGIN
                                      NOSUPERUSER
                                      INHERIT
                                      NOCREATEDB
                                      NOCREATEROLE
                                      NOREPLICATION
                                      ENCRYPTED PASSWORD 'md5hidden';
                                    
                                    CREATE TABLE public.my_table
                                    (
                                        example_column character varying COLLATE pg_catalog."default",
                                    )
                                    
                                    TABLESPACE pg_default;
                                    
                                    ALTER TABLE public.my_table OWNER to postgres;
                                    
                                    GRANT INSERT, SELECT, DELETE ON TABLE public.my_table TO my_user;
                                    

                                    So for example:

                                    sudo -u postgres psql -c 'one of the above blocks of code'
                                    

                                    So here my_db is the database name, my_user is the role I'm using to access the table and my_table is the table name.

                                    1 Reply Last reply
                                    0
                                    • R Offline
                                      R Offline
                                      R-P-H
                                      wrote on last edited by
                                      #34

                                      Is there anything else I can try ?

                                      1 Reply Last reply
                                      0
                                      • SGaistS Offline
                                        SGaistS Offline
                                        SGaist
                                        Lifetime Qt Champion
                                        wrote on last edited by
                                        #35

                                        Sorry I did not had time to test the database.

                                        One thing that you could try (I don't think it would change anything but worth a try), reorder the database setup and add your custom role and it setup both at the end.

                                        Interested in AI ? www.idiap.ch
                                        Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

                                        R 1 Reply Last reply
                                        0
                                        • SGaistS SGaist

                                          Sorry I did not had time to test the database.

                                          One thing that you could try (I don't think it would change anything but worth a try), reorder the database setup and add your custom role and it setup both at the end.

                                          R Offline
                                          R Offline
                                          R-P-H
                                          wrote on last edited by
                                          #36

                                          @SGaist said in QSqlTableModel() empty on Ubuntu but works on Windows ?:

                                          Sorry I did not had time to test the database.

                                          One thing that you could try (I don't think it would change anything but worth a try), reorder the database setup and add your custom role and it setup both at the end.

                                          I guess I could try that but why would the error be

                                          QSqlError("", "Unable to find table logs", "")
                                          

                                          then ?

                                          1 Reply Last reply
                                          0

                                          • Login

                                          • Login or register to search.
                                          • First post
                                            Last post
                                          0
                                          • Categories
                                          • Recent
                                          • Tags
                                          • Popular
                                          • Users
                                          • Groups
                                          • Search
                                          • Get Qt Extensions
                                          • Unsolved