[Solved]Parameter Qt::ItemDataRoles doesn't matchs with the expected values.

[Charlie_Hdz]

Hi guys.

I'm working in a application where I make a custom model from QAbstractItemModel, in this I have a container of a custom class, and I like to show that data in a QTableView. But in the beginning the view dont show the values of the items, so I'm looking over the overrided data function.

@#include "playlistmodel.h"

PlayListModel::PlayListModel()
{
m_lstAudioMetaObj.clear();

}

PlayListModel::~PlayListModel()
{

}

int PlayListModel::rowCount(const QModelIndex &parent) const{
return m_lstAudioMetaObj.size();
}

int PlayListModel::columnCount(const QModelIndex &parent) const{
return 7;
}

QVariant PlayListModel::data(const QModelIndex &index, int role) const{
if(!index.isValid())
return QVariant();
if(index.row()>=m_lstAudioMetaObj.size())
return QVariant();
if(role!=Qt::DisplayRole){ //!
if(index.column()== 0){
QVariant v(m_lstAudioMetaObj[index.row()].artist());
return v;
}
}
else
return QVariant();
}

bool PlayListModel::insertData(const AudioMetaData &audio){

int tempSize=m_lstAudioMetaObj.size();
m_lstAudioMetaObj.append(audio);

if(m_lstAudioMetaObj.size() >tempSize)
    return true;
return false;

}

QVariant PlayListModel::headerData(int section, Qt::Orientation orientation, int role) const{
if(orientation != Qt::Horizontal || role != Qt::DisplayRole)
return QAbstractItemModel::headerData(section,orientation,role);

switch(section){
case 0: return "Name";
case 1: return "Release Time";
case 2: return "Artist";
case 3: return "Album";
case 4: return "Genre";
case 5: return "Rating";
case 6: return "Duration";
}

return QVariant();

}
@

In the line 27 I'm trying to show the data of the respectly AudioMetaData, but the view isn't works and shows:

!http://i1344.photobucket.com/albums/p656/Charlie_Hdz/qtproblem_zpsusvgeyqt.png(http://i1344.photobucket.com/albums/p656/Charlie_Hdz/qtproblem_zpsusvgeyqt.png)!

Then, I looked more deeply and found that the expected roles values wasn't matchs with the expected values (Qt::DisplayRole), throwing the following values:

             Name    Release         Artist                  Album             Genre             Duration     Rating

(Role Value) 6 7 9 10 1 8 ?

Notice that the last column(rating) is ignore and continue with the next row (tested)...So the questions are...

1.-How or Where can I set the values of each AudioMetaValue?

2.- And if that isn't possible. What do you suggest to fix it?

Thank You.

Your trusly, Carlos Hernandez. Wiwiped.

PS. If you need them, I give you the definitions and implementations of the others classes.

@#ifndef PLAYLISTMODEL_H
#define PLAYLISTMODEL_H

#include <QAbstractTableModel>
#include <QModelIndex>
#include <QList>
#include <QVariant>
#include "audiometadata.h"

class PlayListModel : public QAbstractTableModel
{
Q_OBJECT
public:
PlayListModel(QList<AudioMetaData> lst, QObject* parent=0):
QAbstractTableModel(parent),m_lstAudioMetaObj(lst){}
PlayListModel();
~PlayListModel();
//Implemented Function
int rowCount(const QModelIndex &parent= QModelIndex()) const;
int columnCount(const QModelIndex &parent=QModelIndex()) const;
QVariant data(const QModelIndex &index, int role=Qt::DisplayRole) const;
bool insertData(const AudioMetaData& audio);
QVariant headerData(int section, Qt::Orientation orientation, int role) const;

QList<AudioMetaData> list()const{return m_lstAudioMetaObj;}

private:
QList<AudioMetaData>m_lstAudioMetaObj;
};

#endif // PLAYLISTMODEL_H
@

@#include "audiometadata.h"

AudioMetaData::AudioMetaData()
{
qRegisterMetaType<AudioMetaData>("AudioMetaData");
}

AudioMetaData::~AudioMetaData(){}

AudioMetaData::AudioMetaData(const AudioMetaData &other){
*this=other;
}
@

@#ifndef AUDIOMETADATA_H
#define AUDIOMETADATA_H

#include <QObject>
#include <QString>
#include <QDate>
#include <QTime>

class AudioMetaData
{
public:
explicit AudioMetaData(QString n,QDate d,QString a,QString al,
QString g,QTime du,int r):m_name(n),m_dateOfRelease(d),
m_artist(a),m_album(al),m_genre(g),m_duration(du),m_Rating(r){}

//!
AudioMetaData();
~AudioMetaData();
AudioMetaData(const AudioMetaData& other);

//Access Function.
QString name()const{return m_name;}
void setName(QString name){m_name=name;}
QDate dateOfRelease()const{return m_dateOfRelease;}
void setDate(QDate date){m_dateOfRelease=date;}
QString artist()const{return m_artist;}
void setArtist(QString artist){m_artist=artist;}
QString album()const{return m_album;}
void setAlbum(QString album){m_album=album;}
QString genre()const{return m_genre;}
void setGenre(QString genre){m_genre=genre;}
QTime duration()const{return m_duration;}
void setDuration(QTime duration){m_duration=duration;}

private:
QString m_name;
QDate m_dateOfRelease;
QString m_artist;
QString m_album;
QString m_genre;
QTime m_duration;
int m_Rating;
};

Q_DECLARE_METATYPE(AudioMetaData)
#endif // AUDIOMETADATA_H
@

[Charlie_Hdz]

And If you have some suggestion about my code style, It will be appreciated : )

[raven-worx]

you just don return anything for Qt::DisplayRole in your data() method.
So why should the view display anything? :)

Maybe it's a typo but shouldn't it be look like this?!
@
if(role == Qt::DisplayRole){
if(index.column()== 0){
QVariant v(m_lstAudioMetaObj[index.row()].artist());
return v;
}
}
@

[Charlie_Hdz]

Thank you raven.

Well, that part of code is so because I was testing

I'm expeting values of Qt::DisplayRole role, but instead that I saw that values vary as this:

For name column, role value is 6
For release column, role value is 7
...
Duration column, role value is 8
and for rating column, role value is invalidated.

So, the questions are:

Why role values vary as that form when I'm expecting only Qt::DisplayRole because AudioMetaData members are all QString unless Rating (int) ?

How can I ensure Qt::DisplayRole role with my AudioMetaData?

[Charlie_Hdz]

bq. Maybe it’s a typo but shouldn’t it be look like this?!

Yes Indeed, But I saw that that if isn't work so I changed the setence.

[JKSH]

[quote author="Charlie_Hdz" date="1422380725"]Why role values vary as that form when I'm expecting only Qt::DisplayRole because AudioMetaData members are all QString unless Rating (int) ?[/quote]The View will always ask for data from many different roles. This is expected.

For example:

• It asks for Qt::DisplayRole (0) to get the text
• It asks for Qt::BackgroundRole (8) to get the cell colour
• It asks for Qt::ForegroundRole (9) to get the text colour

[SGaist]

Hi,

DisplayRole is only one part of what's needed to show something in a view. The other roles comprises font, text color, background color etc. That's why when you don't hand a particular role you return the value of the base class implementation.

[Charlie_Hdz]

I understand now.

I read some documentation as "Model/View Tutorial":http://qt-project.org/doc/qt-4.8/modelview.html and "Model/View Programming":http://qt-project.org/doc/qt-4.8/model-view-programming.html#creating-new-models again

So I only make some changes and everything work excellent.

@QVariant PlayListModel::data(const QModelIndex &index, int role) const{
if(!index.isValid())
return QVariant();
if(index.row()>=m_lstAudioMetaObj.size())
return QVariant();
if(role == Qt::DisplayRole){
int column=index.column(); int row=index.row();

   switch(column){
   case 0:            return QString("%1").arg(m_lstAudioMetaObj.at(row).name());
   case 1:           return QString("%1").arg(m_lstAudioMetaObj.at(row).dateOfRelease()
                                              .toString());
   case 2:           return QString("%1").arg(m_lstAudioMetaObj.at(row).artist());
   case 3:           return QString("%1").arg(m_lstAudioMetaObj.at(row).album());
   case 4:           return QString("%1").arg(m_lstAudioMetaObj.at(row).genre());
   case 5:           return QString("%1").arg(m_lstAudioMetaObj.at(row).duration().toString());
   case 6:           return QString("%1").arg(m_lstAudioMetaObj.at(row).rating());
       }

}
else
return QVariant();
}@

!http://i1344.photobucket.com/albums/p656/Charlie_Hdz/qtproblem1_zpssgh3yzid.png(http://i1344.photobucket.com/albums/p656/Charlie_Hdz/qtproblem1_zpssgh3yzid.png)!

So I'll continue with my projects...

Thank you everyone.