Qt MVC入门2 - 可以编辑的自定义模型

#ifndef STRINGLISTMODEL_H
#define STRINGLISTMODEL_H

#include <QAbstractListModel>
#include <QModelIndex>
#include <QStringList>


class StringListModel : public QAbstractListModel
{
    Q_OBJECT

public:
    StringListModel(const QStringList &strings, QObject *parent = 0)
        : QAbstractListModel(parent), stringList(strings) {}

    int rowCount(const QModelIndex &parent = QModelIndex()) const;
    QVariant data(const QModelIndex &index, int role) const;
    QVariant headerData(int section, Qt::Orientation orientation,
                        int role = Qt::DisplayRole) const;

    Qt::ItemFlags flags(const QModelIndex &index) const;
          bool setData(const QModelIndex &index, const QVariant &value,
                       int role = Qt::EditRole);

private:
    QStringList stringList;
};

#endif // STRINGLISTMODEL_H

#include "stringlistmodel.h"

int StringListModel::rowCount(const QModelIndex &parent) const
  {
      return stringList.count();
  }

QVariant StringListModel::data(const QModelIndex &index, int role) const
  {
      if (!index.isValid())
          return QVariant();

      if (index.row() >= stringList.size())
          return QVariant();

      if (role == Qt::DisplayRole || role == Qt::EditRole)
          return stringList.at(index.row());
      else
          return QVariant();
  }

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

      if (orientation == Qt::Horizontal)
          return QString("Column %1").arg(section);
      else
          return QString("Row %1").arg(section);
  }

Qt::ItemFlags StringListModel::flags(const QModelIndex &index) const
  {
      if (!index.isValid())
          return Qt::ItemIsEnabled;

      return QAbstractItemModel::flags(index) | Qt::ItemIsEditable;
  }

bool StringListModel::setData(const QModelIndex &index,
                                const QVariant &value, int role)
  {
      if (index.isValid() && role == Qt::EditRole) {

          stringList.replace(index.row(), value.toString());
          emit dataChanged(index, index);
          return true;
      }
      return false;
  }

文章来自与Qt官方文档:帮助文档检索 model/view programming

An editable model

The read-only model shows how simple choices could be presented to the user but, for many applications, an editable list model is much more useful. We can modify the read-only model to make the items editable by changing the data() function we implemented for read-only, and by implementing two extra functions: flags() and setData(). The following function declarations are added to the class definition:

Making the model editable

A delegate checks whether an item is editable before creating an editor. The model must let the delegate know that its items are editable. We do this by returning the correct flags for each item in the model; in this case, we enable all items and make them both selectable and editable:

Note that we do not have to know how the delegate performs the actual editing process. We only have to provide a way for the delegate to set the data in the model. This is achieved through the setData() function:

In this model, the item in the string list that corresponds to the model index is replaced by the value provided. However, before we can modify the string list, we must make sure that the index is valid, the item is of the correct type, and that the role is supported. By convention, we insist that the role is the EditRole since this is the role used by the standard item delegate. For boolean values, however, you can use Qt::CheckStateRole and set the Qt::ItemIsUserCheckable flag; a checkbox is then used for editing the value. The underlying data in this model is the same for all roles, so this detail just makes it easier to integrate the model with standard components.

When the data has been set, the model must let the views know that some data has changed. This is done by emitting the dataChanged() signal. Since only one item of data has changed, the range of items specified in the signal is limited to just one model index.

Also the data() function needs to be changed to add the Qt::EditRole test: