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Encoding in the QTableView

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  • SGaistS Offline
    SGaistS Offline
    SGaist
    Lifetime Qt Champion
    wrote on last edited by
    #17

    Where's that hash located ?
    Did you set your custom QStyledItem delegate on the correct column of your QTableView ?
    Are you sure that the volume contains the correct values ?

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    Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

    ro12man3R 1 Reply Last reply
    0
    • SGaistS SGaist

      Where's that hash located ?
      Did you set your custom QStyledItem delegate on the correct column of your QTableView ?
      Are you sure that the volume contains the correct values ?

      ro12man3R Offline
      ro12man3R Offline
      ro12man3
      wrote on last edited by ro12man3
      #18

      @SGaist this is the code

      void MainWindow::on_pushButton_clicked() // I click and the quiery result is showing in the qtableview
      {
      QSqlQueryModel * model = new QSqlQueryModel(0);
      QHash< int, QString> hash;
       hash.insert(100, "Jackson");
      model->setQuery("select city-codes from country");
      ui->tableView->setModel(model);
      }
      
      1 Reply Last reply
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      • SGaistS Offline
        SGaistS Offline
        SGaist
        Lifetime Qt Champion
        wrote on last edited by
        #19

        That hash is destroyed at the end of on_pushButton_clicked

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

        ro12man3R 1 Reply Last reply
        0
        • SGaistS SGaist

          That hash is destroyed at the end of on_pushButton_clicked

          ro12man3R Offline
          ro12man3R Offline
          ro12man3
          wrote on last edited by
          #20

          @SGaist so what I need to do for the correct changing values in my tableview?
          Where I need to write the QHash function?

          1 Reply Last reply
          0
          • SGaistS Offline
            SGaistS Offline
            SGaist
            Lifetime Qt Champion
            wrote on last edited by
            #21

            Either in your QStyledItemDelegate or as @mrjj suggested pass it to the delegate e.g. at construction time.

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            Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

            ro12man3R 1 Reply Last reply
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            • SGaistS SGaist

              Either in your QStyledItemDelegate or as @mrjj suggested pass it to the delegate e.g. at construction time.

              ro12man3R Offline
              ro12man3R Offline
              ro12man3
              wrote on last edited by
              #22

              @SGaist what will be more simple? Cause I don't know how to make that. Sorry about my not big skills in qt

              mrjjM 1 Reply Last reply
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              • SGaistS Offline
                SGaistS Offline
                SGaist
                Lifetime Qt Champion
                wrote on last edited by
                #23

                In your QStyledItemDelegate, read your file and build the hash with its content. Then in your displayText reimplementation return _hash.value(value.toInt(), tr("Not found"));

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                • ro12man3R ro12man3

                  @SGaist what will be more simple? Cause I don't know how to make that. Sorry about my not big skills in qt

                  mrjjM Offline
                  mrjjM Offline
                  mrjj
                  Lifetime Qt Champion
                  wrote on last edited by
                  #24

                  @ro12man3
                  hi
                  Starting with models and view are not best intro to Qt.
                  They are very powerful but does demand some c++ skills and reading the docs.

                  Sometimes code is easier to understand so I made u sample with @SGaist help.

                  It has a list of names and if it sees Lars, it replaced it with BANNED.
                  For your code, you will use the hash to look up the name from the code.

                  https://www.dropbox.com/s/vsiqjrr41jhafqo/myfirstview.zip?dl=0

                  the key points to understand is:
                  we make a new class to override the default behaviour

                  class MyDelegate : public QStyledItemDelegate {
                  public:
                  MyDelegate(QObject* parent)
                  : QStyledItemDelegate(parent) {}
                  virtual QString displayText(const QVariant& value, const QLocale& locale) const;
                  };

                  We set this delegate ONLY to the column we need.

                  • ui->tableView->setItemDelegateForColumn(0, new MyDelegate(this));

                  the displayText is the key function.:

                  QString MyDelegate::displayText(const QVariant& value, const QLocale& locale) const {
                  if (value.toString().compare("Lars") == 0) // if found
                  return "BANNED";
                  else
                  return value.toString(); // else just return data unchanged
                  }

                  Here u will replace the city-code with names using the hash.

                  Hope this helps you.

                  ro12man3R 1 Reply Last reply
                  1
                  • mrjjM mrjj

                    @ro12man3
                    hi
                    Starting with models and view are not best intro to Qt.
                    They are very powerful but does demand some c++ skills and reading the docs.

                    Sometimes code is easier to understand so I made u sample with @SGaist help.

                    It has a list of names and if it sees Lars, it replaced it with BANNED.
                    For your code, you will use the hash to look up the name from the code.

                    https://www.dropbox.com/s/vsiqjrr41jhafqo/myfirstview.zip?dl=0

                    the key points to understand is:
                    we make a new class to override the default behaviour

                    class MyDelegate : public QStyledItemDelegate {
                    public:
                    MyDelegate(QObject* parent)
                    : QStyledItemDelegate(parent) {}
                    virtual QString displayText(const QVariant& value, const QLocale& locale) const;
                    };

                    We set this delegate ONLY to the column we need.

                    • ui->tableView->setItemDelegateForColumn(0, new MyDelegate(this));

                    the displayText is the key function.:

                    QString MyDelegate::displayText(const QVariant& value, const QLocale& locale) const {
                    if (value.toString().compare("Lars") == 0) // if found
                    return "BANNED";
                    else
                    return value.toString(); // else just return data unchanged
                    }

                    Here u will replace the city-code with names using the hash.

                    Hope this helps you.

                    ro12man3R Offline
                    ro12man3R Offline
                    ro12man3
                    wrote on last edited by ro12man3
                    #25

                    @mrjj ohhh thank you! It works!! Thank you very much.

                    But I have 40 values that I will need to change(if it will be in quiery result).

                    1. I can't write 40 "else if".. "else if"... "else if".... That's unlogic.
                    2. I need to write all that values in support *.txt file(or another, the main is a simple format for editing), cause if I will write all that values in the program and then I will need to add new values...That's will be very uncomfortable.

                    I see the method of the working the function so:
                    The function is searching the values(from *.txt file) that has a quiery result. If it will find, then it will change to another every value.

                    But...how make that in reality?

                    1 Reply Last reply
                    0
                    • mrjjM Offline
                      mrjjM Offline
                      mrjj
                      Lifetime Qt Champion
                      wrote on last edited by
                      #26

                      hi
                      it sounds like your best way would to read in
                      the text file to a hash.
                      and use that hash in displayText
                      I agree, using if for 40 values would be nasty :)

                      How does your text file look like?

                      ro12man3R 1 Reply Last reply
                      0
                      • mrjjM mrjj

                        hi
                        it sounds like your best way would to read in
                        the text file to a hash.
                        and use that hash in displayText
                        I agree, using if for 40 values would be nasty :)

                        How does your text file look like?

                        ro12man3R Offline
                        ro12man3R Offline
                        ro12man3
                        wrote on last edited by
                        #27

                        @mrjj I didn't create that file, cause I have no idea. Well, every variant will be good. The main is the working code :D

                        Do you think that *.txt file should looks so:

                        hash.insert("123", "Jack Sparrow");
                        hash.insert("134", "Elvis Presley");
                        hash.insert("201", "Walter White");
                        ........
                        

                        ?

                        mrjjM 1 Reply Last reply
                        0
                        • ro12man3R ro12man3

                          @mrjj I didn't create that file, cause I have no idea. Well, every variant will be good. The main is the working code :D

                          Do you think that *.txt file should looks so:

                          hash.insert("123", "Jack Sparrow");
                          hash.insert("134", "Elvis Presley");
                          hash.insert("201", "Walter White");
                          ........
                          

                          ?

                          mrjjM Offline
                          mrjjM Offline
                          mrjj
                          Lifetime Qt Champion
                          wrote on last edited by
                          #28

                          @ro12man3
                          Hi
                          For me it sounds like you would have a text file with
                          1000, NAME1
                          1001, NAME2

                          so when u see int 1000, u want "NAME" etc.

                          So your task is to look at QFile and read in a text file with your format and stuff it into a hash.
                          Then use it.

                          ro12man3R 1 Reply Last reply
                          0
                          • mrjjM mrjj

                            @ro12man3
                            Hi
                            For me it sounds like you would have a text file with
                            1000, NAME1
                            1001, NAME2

                            so when u see int 1000, u want "NAME" etc.

                            So your task is to look at QFile and read in a text file with your format and stuff it into a hash.
                            Then use it.

                            ro12man3R Offline
                            ro12man3R Offline
                            ro12man3
                            wrote on last edited by
                            #29

                            @mrjj ok, I understand how to read the file and search the values. I don't understand another thing.
                            On example=, the function will read the .txt file and it will find some value. Let it be 2900.
                            In txt file it will be looking:
                            2900, "Jackson"

                            How to convert to "Jackson"? I don't know how to write that in a hash. How the hash will look the "convert value"?

                            mrjjM 1 Reply Last reply
                            0
                            • ro12man3R ro12man3

                              @mrjj ok, I understand how to read the file and search the values. I don't understand another thing.
                              On example=, the function will read the .txt file and it will find some value. Let it be 2900.
                              In txt file it will be looking:
                              2900, "Jackson"

                              How to convert to "Jackson"? I don't know how to write that in a hash. How the hash will look the "convert value"?

                              mrjjM Offline
                              mrjjM Offline
                              mrjj
                              Lifetime Qt Champion
                              wrote on last edited by mrjj
                              #30

                              @ro12man3
                              say
                              u define the hash like
                              QHash<int, QString> Hash;
                              it means we use int as key and get string as result
                              so
                              QString Name=hash[2900];
                              would give us "Jackson" in name;

                              please read doc on how it works.
                              http://doc.qt.io/qt-5/qhash.html

                              so you would read all lines from text file and insert into hash.

                              ro12man3R 1 Reply Last reply
                              1
                              • mrjjM mrjj

                                @ro12man3
                                say
                                u define the hash like
                                QHash<int, QString> Hash;
                                it means we use int as key and get string as result
                                so
                                QString Name=hash[2900];
                                would give us "Jackson" in name;

                                please read doc on how it works.
                                http://doc.qt.io/qt-5/qhash.html

                                so you would read all lines from text file and insert into hash.

                                ro12man3R Offline
                                ro12man3R Offline
                                ro12man3
                                wrote on last edited by
                                #31

                                @mrjj woooow thank you! You are the master! :) I understand, very clever idea!

                                I will try that in the morning.

                                1 Reply Last reply
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                                • mrjjM Offline
                                  mrjjM Offline
                                  mrjj
                                  Lifetime Qt Champion
                                  wrote on last edited by mrjj
                                  #32

                                  well for 40 lookups its more fun that tons of ifs
                                  if u make a text file with
                                  ID, NAME
                                  like
                                  1000, TOWN
                                  1001, TOWN2
                                  1002, TOWN3

                                  so u need to ( code handwritten fast, not tested. u need to add includes)

                                  QFile file("c:/mynames.txt");
                                  if(!file.open(QIODevice::ReadOnly)) {
                                  QMessageBox::information(0, "error", file.errorString());
                                  }

                                  QTextStream in(&file);
                                  while(!in.atEnd()) {
                                  QString line = in.readLine(); // get a line from file
                                  QStringList fields = line.split(","); <<< KEY point. we ask it to split the text at "," to a list
                                  /// now fields[0] is first part and fields[1] is rest
                                  // so
                                  hash[fields[0].toInt()] = fields[1] ; // store name under key
                                  }

                                  file.close();

                                  ro12man3R 1 Reply Last reply
                                  1
                                  • mrjjM mrjj

                                    well for 40 lookups its more fun that tons of ifs
                                    if u make a text file with
                                    ID, NAME
                                    like
                                    1000, TOWN
                                    1001, TOWN2
                                    1002, TOWN3

                                    so u need to ( code handwritten fast, not tested. u need to add includes)

                                    QFile file("c:/mynames.txt");
                                    if(!file.open(QIODevice::ReadOnly)) {
                                    QMessageBox::information(0, "error", file.errorString());
                                    }

                                    QTextStream in(&file);
                                    while(!in.atEnd()) {
                                    QString line = in.readLine(); // get a line from file
                                    QStringList fields = line.split(","); <<< KEY point. we ask it to split the text at "," to a list
                                    /// now fields[0] is first part and fields[1] is rest
                                    // so
                                    hash[fields[0].toInt()] = fields[1] ; // store name under key
                                    }

                                    file.close();

                                    ro12man3R Offline
                                    ro12man3R Offline
                                    ro12man3
                                    wrote on last edited by
                                    #33

                                    @mrjj thank you very much!! I will try that. If I wiil edit this, I will write here the correct code.
                                    Thank you for your helping!

                                    mrjjM 1 Reply Last reply
                                    0
                                    • ro12man3R ro12man3

                                      @mrjj thank you very much!! I will try that. If I wiil edit this, I will write here the correct code.
                                      Thank you for your helping!

                                      mrjjM Offline
                                      mrjjM Offline
                                      mrjj
                                      Lifetime Qt Champion
                                      wrote on last edited by
                                      #34

                                      @ro12man3
                                      You are very welcome.
                                      One note is that if u read in text lines then
                                      it will be text so u need to convert to int for the key if you
                                      define the hash like that.
                                      QHash<int, QString> Hash;
                                      something like
                                      hash[ fields[0].toInt() ]=xxx
                                      If it gives u grief , let me know as im not 100% sure of syntax as its free writing :)

                                      ro12man3R 1 Reply Last reply
                                      0
                                      • mrjjM mrjj

                                        @ro12man3
                                        You are very welcome.
                                        One note is that if u read in text lines then
                                        it will be text so u need to convert to int for the key if you
                                        define the hash like that.
                                        QHash<int, QString> Hash;
                                        something like
                                        hash[ fields[0].toInt() ]=xxx
                                        If it gives u grief , let me know as im not 100% sure of syntax as its free writing :)

                                        ro12man3R Offline
                                        ro12man3R Offline
                                        ro12man3
                                        wrote on last edited by ro12man3
                                        #35

                                        @mrjj Well, I can extract the second field, but it will be all second fields.

                                        And I have edited the code:

                                        QString MyDelegate::displayText(const QVariant& value, const QLocale& locale) const {
                                               QString line;
                                                QFile file("C:/QT/Test text/1.txt");
                                                if(!file.open(QIODevice::ReadOnly))
                                                       qDebug() << "Error opening file";
                                                QTextStream in(&file);
                                        
                                                QHash<int, QString> hash;
                                        
                                                 while(!in.atEnd()) {
                                                 QString line = in.readLine(); 
                                                 QStringList fields = line.split(","); 
                                                 hash[fields[0].toInt()] = fields[1] ; 
                                          if (value.toString().compare(fields[0]) == 0)
                                            return fields[1];
                                          else
                                            return value.toString(); 
                                        }
                                        }
                                        

                                        And it doesn't work. How to solve that?
                                        It was working when I wrote

                                         if (value.toString().compare("1000") == 0)
                                            return "Jackson";
                                        

                                        If I write

                                        QMessageBox::information(this, fields[0], fields[1] );
                                        

                                        it is working, but it shows ALL values.

                                        1 Reply Last reply
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                                        • mrjjM Offline
                                          mrjjM Offline
                                          mrjj
                                          Lifetime Qt Champion
                                          wrote on last edited by mrjj
                                          #36

                                          @ro12man3 said:

                                          And it doesn't work. How to solve that?

                                          • You really have to provide more info that that :)
                                            if you insert qDebug() << "f1=" << fields[0] << "f2=" << fields[1];
                                            does it read in the data correctly ? this is critical.

                                          • Also you build the hash
                                            hash[fields[0].toInt()] = fields[1] ;
                                            but don't use it. ? You dont use it to look up the text.
                                            QString CityName = hash[value.toInt()];
                                            return CityName;

                                          • Also you mix reading in the file with compare value. that is wrong.
                                            You should not read it in displayText as it will then read file each time
                                            it draw that column. that is not so good.
                                            Make Hash a member of the class. (in .h) and just use it
                                            in displayText. then u can read it once and use it over and over.

                                          • Read in the text file in the constructor of the delegate;

                                          ro12man3R 1 Reply Last reply
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