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Thread: A simplest ListModel... no example :(

  1. #1
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    Question A simplest ListModel... no example :(

    Hi!
    I'm trying to make a simplest ListModel accessing QList<Class>.
    Could someone take a look and tell me how it should be written?
    feed.h:
    Qt Code:
    1. class Feed
    2. {
    3. public:
    4. Feed();
    5. Feed(const Feed &other);
    6. Feed &operator=(const Feed &other);
    7.  
    8. QString stringUrl;
    9. QDate lastFetched;
    10. QString htmlContent;
    11. };
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    feedModel.h:
    Qt Code:
    1. class Feed;
    2. #include <QAbstractListModel>
    3. class FeedModel : public QAbstractListModel
    4. {
    5. public:
    6. int rowCount ( const QModelIndex & parent = QModelIndex() ) const;
    7. QVariant data ( const QModelIndex & index, int role = Qt::DisplayRole ) const;
    8. private:
    9. QList<Feed> list;
    10.  
    11. };
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    feedModel.cpp:
    Qt Code:
    1. #include "feedModel.h"
    2. #include "feed.h"
    3.  
    4. #include <QAbstractListModel>
    5.  
    6. int FeedModel::rowCount ( const QModelIndex & parent ) const
    7. {
    8. if (!parent.isValid())
    9. return (-1);
    10. else
    11. return list.count();
    12. }
    13.  
    14. QVariant FeedModel::data ( const QModelIndex & index, int role ) const
    15. {
    16. if (!index.isValid())
    17. return QVariant();
    18.  
    19. if (role != Qt::DisplayRole)
    20. return QVariant();
    21. // This is the hardest place for me!
    22. // Feed *item = static_cast<Feed*>(index.internalPointer());
    23. Feed item = static_cast<Feed>(list.at(index.row()));
    24.  
    25. switch (index.column()) {
    26. case 0:
    27. return item.stringUrl;
    28. default:
    29. return QVariant();
    30. }
    31. }
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    Regards!
    Last edited by tomek; 6th January 2006 at 23:47.

  2. #2
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    Default Re: A simplest ListModel... no example :(

    You provided invalid addresses for those files. Please attach them properly using the attachment feature. Or post your code here using the [code] tag.

  3. #3
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    Default Re: A simplest ListModel... no example :(

    Quote Originally Posted by tomek
    Could someone take a look and tell me how it should be written?
    You can find a short tutorial here.

  4. #4
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    Default Re: A simplest ListModel... no example :(

    Quote Originally Posted by tomek
    Qt Code:
    1. // This is the hardest place for me!
    2. // Feed *item = static_cast<Feed*>(index.internalPointer());
    3. Feed item = static_cast<Feed>(list.at(index.row()));
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    list is a QList<Feed>, so list.at( x ) will return a reference to a Feed instance --- you don't need any casts.
    Qt Code:
    1. int row = index.row();
    2. if( 0 <= row && row < list.size() ) {
    3. return QVariant();
    4. }
    5. const Feed& item = list.at( row );
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  5. #5
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    Default Re: A simplest ListModel... no example :(

    Quote Originally Posted by tomek
    Qt Code:
    1. int FeedModel::rowCount ( const QModelIndex & parent ) const
    2. {
    3. if (!parent.isValid())
    4. return (-1);
    5. else
    6. return list.count();
    7. }
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    Why so? parent is not valid for first level or hierarchy, thus you should return list.count() here...

    Qt Code:
    1. int FeedModel::rowCount ( const QModelIndex & parent ) const
    2. {
    3. return list.count(); // the model is not hierarchical, so parent is always invalid
    4. }
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    data() looks fine.

    Please note that your model is read only!

  6. #6
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    Default Re: A simplest ListModel... no example :(

    Thank you. Now it's all right!
    I think I should improve my C++...
    Have a good weekend.

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