真正的交易是查询结果的主键。QSqlTableModel::primaryKey()Qt 的 API 提供了从列列表到列列表的相当迂回的路径。结果primaryKey()是 a QSqlRecord，您可以遍历它field()s以查看它们是什么。您还可以从 中查找构成查询的所有字段QSqlTableModel::record()。您在后者中找到前者以获取构成查询的模型列的列表。
如果您的查询不包含主键，则您必须自己设计一个并使用某种协议提供它。例如，您可以选择如果primaryKey().isEmpty()为 true，则将模型返回的最后一列用作主键。由您决定如何键入任意查询的结果。
然后可以简单地通过它们的主键（组成键的单元格的值列表 - a ）对选定的行进行索引QVariantList。为此，如果其设计没有损坏，您可以使用自定义选择模型( )。QItemSelectionModel关键方法，例如isRowSelected()不是虚拟的，你不能重新实现它们:(。
相反，您可以通过为数据提供自定义来使用模拟选择的代理模型Qt::BackgroundRole。您的模型位于表模型的顶部，并保留了选定键的排序列表。每次data()调用代理模型时，您都会从底层查询模型中获取行的键，然后在排序列表中搜索它。最后，如果该项目被选中，您将返回一个自定义背景角色。您必须为QVariantList. 如果QItemSelectionModel可用于此目的，您可以将此功能放入isRowSelected().
该模型是通用的，因为您订阅了用于从查询模型中提取键的特定协议：即使用primaryKey().
如果模型支持，您也可以使用持久索引，而不是显式使用主键。唉，至少在 Qt 5.3.2 之前，在QSqlTableModel重新运行查询时不会保留持久索引。因此，一旦视图更改了排序顺序，持久索引就会变得无效。
下面是一个完整的示例，说明如何实现这样的野兽：
#include <QApplication>
#include <QTableView>
#include <QSqlRecord>
#include <QSqlField>
#include <QSqlQuery>
#include <QSqlTableModel>
#include <QIdentityProxyModel>
#include <QSqlDatabase>
#include <QMap>
#include <QVBoxLayout>
#include <QPushButton>
// Lexicographic comparison for a variant list
bool operator<(const QVariantList &a, const QVariantList &b) {
int count = std::max(a.count(), b.count());
// For lexicographic comparison, null comes before all else
Q_ASSERT(QVariant() < QVariant::fromValue(-1));
for (int i = 0; i < count; ++i) {
auto aValue = i < a.count() ? a.value(i) : QVariant();
auto bValue = i < b.count() ? b.value(i) : QVariant();
if (aValue < bValue) return true;
}
return false;
}
class RowSelectionEmulatorProxy : public QIdentityProxyModel {
Q_OBJECT
Q_PROPERTY(QBrush selectedBrush READ selectedBrush WRITE setSelectedBrush)
QMap<QVariantList, QModelIndex> mutable m_selection;
QVector<int> m_roles;
QBrush m_selectedBrush;
bool m_ignoreReset;
class SqlTableModel : public QSqlTableModel {
public:
using QSqlTableModel::primaryValues;
};
SqlTableModel * source() const {
return static_cast<SqlTableModel*>(dynamic_cast<QSqlTableModel*>(sourceModel()));
}
QVariantList primaryValues(int row) const {
auto record = source()->primaryValues(row);
QVariantList values;
for (int i = 0; i < record.count(); ++i) values << record.field(i).value();
return values;
}
void notifyOfChanges(int row) {
emit dataChanged(index(row, 0), index(row, columnCount()-1), m_roles);
}
void notifyOfAllChanges(bool remove = false) {
auto it = m_selection.begin();
while (it != m_selection.end()) {
if (it->isValid()) notifyOfChanges(it->row());
if (remove) it = m_selection.erase(it); else ++it;
}
}
public:
RowSelectionEmulatorProxy(QObject* parent = 0) :
QIdentityProxyModel(parent), m_roles(QVector<int>() << Qt::BackgroundRole),
m_ignoreReset(false) {
connect(this, &QAbstractItemModel::modelReset, [this]{
if (! m_ignoreReset) {
m_selection.clear();
} else {
for (auto it = m_selection.begin(); it != m_selection.end(); ++it) {
*it = QModelIndex(); // invalidate the cached mapping
}
}
});
}
QBrush selectedBrush() const { return m_selectedBrush; }
void setSelectedBrush(const QBrush & brush) {
if (brush == m_selectedBrush) return;
m_selectedBrush = brush;
notifyOfAllChanges();
}
QList<int> selectedRows() const {
QList<int> result;
for (auto it = m_selection.begin(); it != m_selection.end(); ++it) {
if (it->isValid()) result << it->row();
}
return result;
}
bool isRowSelected(const QModelIndex &proxyIndex) const {
if (! source() || proxyIndex.row() >= rowCount()) return false;
auto primaryKey = primaryValues(proxyIndex.row());
return m_selection.contains(primaryKey);
}
Q_SLOT void selectRow(const QModelIndex &proxyIndex, bool selected = true) {
if (! source() || proxyIndex.row() >= rowCount()) return;
auto primaryKey = primaryValues(proxyIndex.row());
if (selected) {
m_selection.insert(primaryKey, proxyIndex);
} else {
m_selection.remove(primaryKey);
}
notifyOfChanges(proxyIndex.row());
}
Q_SLOT void toggleRowSelection(const QModelIndex &proxyIndex) {
selectRow(proxyIndex, !isRowSelected(proxyIndex));
}
Q_SLOT virtual void clearSelection() {
notifyOfAllChanges(true);
}
QVariant data(const QModelIndex &proxyIndex, int role) const Q_DECL_OVERRIDE {
QVariant value = QIdentityProxyModel::data(proxyIndex, role);
if (proxyIndex.row() < rowCount() && source()) {
auto primaryKey = primaryValues(proxyIndex.row());
auto it = m_selection.find(primaryKey);
if (it != m_selection.end()) {
// update the cache
if (! it->isValid()) *it = proxyIndex;
// return the background
if (role == Qt::BackgroundRole) return m_selectedBrush;
}
}
return value;
}
bool setData(const QModelIndex &, const QVariant &, int) Q_DECL_OVERRIDE {
return false;
}
void sort(int column, Qt::SortOrder order) Q_DECL_OVERRIDE {
m_ignoreReset = true;
QIdentityProxyModel::sort(column, order);
m_ignoreReset = false;
}
void setSourceModel(QAbstractItemModel * model) Q_DECL_OVERRIDE {
m_selection.clear();
QIdentityProxyModel::setSourceModel(model);
}
};
int main(int argc, char *argv[])
{
QApplication app(argc, argv);
QWidget w;
QVBoxLayout layout(&w);
QSqlDatabase db = QSqlDatabase::addDatabase("QSQLITE");
db.setDatabaseName(":memory:");
if (! db.open()) return 255;
QSqlQuery query(db);
query.exec("create table chaps (name, age, constraint pk primary key (name, age));");
query.exec("insert into chaps (name, age) values "
"('Bob', 20), ('Rob', 30), ('Sue', 25), ('Hob', 40);");
QSqlTableModel model(nullptr, db);
model.setTable("chaps");
RowSelectionEmulatorProxy proxy;
proxy.setSourceModel(&model);
proxy.setSelectedBrush(QBrush(Qt::yellow));
QTableView view;
view.setModel(&proxy);
view.setEditTriggers(QAbstractItemView::NoEditTriggers);
view.setSelectionMode(QAbstractItemView::NoSelection);
view.setSortingEnabled(true);
QObject::connect(&view, &QAbstractItemView::clicked, [&proxy](const QModelIndex & index){
proxy.toggleRowSelection(index);
});
QPushButton clearSelection("Clear Selection");
QObject::connect(&clearSelection, &QPushButton::clicked, [&proxy]{ proxy.clearSelection(); });
layout.addWidget(&view);
layout.addWidget(&clearSelection);
w.show();
app.exec();
}
#include "main.moc"