QTreeView - Children Displaying Same Data As Parent, WhatsThisRole is Not

[vulcan]

Does anyone have any ideas? I'm stuck going in circles and can't seem to find where the issue is. Is there any additional information I can provide, or perhaps things I can look for?

Thanks!

[wysota]

This is surely invalid:

void ParseNode::addChild(ParseNode *child)
{
    if(child && children.indexOf(child) == 0);  // <--- semicolon here?
        children.push_back(child);
}

void ParseNode::addChild(ParseNode *child)
{
    if(child && children.indexOf(child) == 0);  // <--- semicolon here?
        children.push_back(child);
}

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In my opinion it should be:

void ParseNode::addChild(ParseNode *child)
{
    if(child && children.indexOf(child) < 0) {
        children.push_back(child);
        child->myParent = this;
    }
}

void ParseNode::addChild(ParseNode *child)
{
    if(child && children.indexOf(child) < 0) {
        children.push_back(child);
        child->myParent = this;
    }
}

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removeChild() has to be adjusted accordingly.

ParseList::addPaths() looks invalid as well.... You're (incorrectly) informing the model that you'll be adding top-level items but then you're never attaching items you're adding to the root node (you only set it as the new item's parent but never add it to the root node's list of children thus parent() implementation can't work correctly). Maybe there are other problems as well, I can't see them right now.

A minimal tree implementation looks more or less like this:

#include <QApplication>
#include <QAbstractItemModel>
#include <QTreeView>
 
template<typename T> class Node {
public:
	Node() { parentNode = 0; }
	~Node() {
		if(parentNode)
			parentNode->removeChild(this);
		qDeleteAll(children);
	}
	void addChild(Node *n) {
		if(n->parentNode) {
			if(n->parentNode == this) return;
			n->parentNode->removeChild(n);
			n->parentNode = 0;
		}
		n->parentNode = this;
		children.append(n);
	}
	void removeChild(Node *n) {
		if(n->parentNode != this) return;
		n->parentNode = 0;
		children.removeOne(n);
	}
	int indexOf(Node *n) const { return children.indexOf(n); }
	Node *at(int idx) const { return children.at(idx); }
	int count() const { return children.count(); }
	Node *parent() const { return parentNode; }
	T data;
 
private:
	Node<T> *parentNode;
	QList<Node<T>*> children;
};
 
template<typename T, int ColCount> class TreeModel : public QAbstractItemModel {
public:
	TreeModel(QObject *parent = 0) : QAbstractItemModel(parent) {
		root = new Node<T>();
	}
	~TreeModel() { delete root; }
	int rowCount(const QModelIndex &parent = QModelIndex()) const {
		return nodeFromIndex(parent)->count();
	}
	int columnCount(const QModelIndex &parent = QModelIndex()) const {
		return ColCount;
	}
	QModelIndex index(int row, int column, const QModelIndex &parent = QModelIndex()) const {
		Node<T> *parentNode = nodeFromIndex(parent);
		if(row < 0 || row >= parentNode->count() || column < 0 || column >= ColCount) return QModelIndex();
		return createIndex(row, column, parentNode->at(row));
	}
	QModelIndex parent(const QModelIndex &child) const {
		Node<T> *childNode = nodeFromIndex(child);
		Node<T> *parentNode = childNode->parent();
		if(parentNode == root) return QModelIndex();
		Node<T> *grandparentNode = parentNode->parent();
		return createIndex(grandparentNode->indexOf(parentNode), 0, parentNode);
	}
	QVariant data(const QModelIndex &index, int role) const {
		qWarning("Reimplement in subclass");
		return QVariant();
	}
protected:
	Node<T>* nodeFromIndex(const QModelIndex &idx) const {
		if(idx.isValid()) return static_cast<Node<T>*>(idx.internalPointer());
		return root;
	}
	Node<T> *root;
};
 
class Model : public TreeModel<int, 1> {
public:
	Model(QObject *parent = 0) : TreeModel(parent) {}
	QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const {
		if(index.column() != 0) return QVariant();
		if(role != Qt::DisplayRole && role != Qt::EditRole) return QVariant();
		Node<int> *n = nodeFromIndex(index);
		return n->data;
	}
	bool setData(const QModelIndex &index, const QVariant &value, int role = Qt::EditRole) {
		if(index.column() != 0) return false;
		if(role != Qt::DisplayRole && role != Qt::EditRole) return false;
		Node<int> *n = nodeFromIndex(index);
		if(n->data != value.toInt()) {
			n->data = value.toInt();
			emit dataChanged(index, index);
			return true;
		}
		return true;
	}
	void addItem(int dat) {
		beginInsertRows(QModelIndex(), root->count(), root->count());
		Node<int> *n = new Node<int>();
		n->data = dat;
		Node<int> *sn = new Node<int>();
		sn->data = dat*10;
		n->addChild(sn);
		root->addChild(n);
		endInsertRows();
	}
};
 
class Adder : public QObject {
public:
	Adder(Model *model, int interval = 2000) {
		m_model = model;
		startTimer(interval);
	}
protected:
	void timerEvent(QTimerEvent *) {
		int val = rand() % 100;
		m_model->addItem(val);
	}
 
private:
	Model *m_model;
};
 
int main(int argc, char *argv[])
{
	QApplication a(argc, argv);
	QTreeView w;
	Model model;
//	TreeModel<int,1> model;
	w.setModel(&model);
	w.show();
	Adder adder(&model, 1000);
	return a.exec();
}

#include <QApplication>
#include <QAbstractItemModel>
#include <QTreeView>

template<typename T> class Node {
public:
	Node() { parentNode = 0; }
	~Node() {
		if(parentNode)
			parentNode->removeChild(this);
		qDeleteAll(children);
	}
	void addChild(Node *n) {
		if(n->parentNode) {
			if(n->parentNode == this) return;
			n->parentNode->removeChild(n);
			n->parentNode = 0;
		}
		n->parentNode = this;
		children.append(n);
	}
	void removeChild(Node *n) {
		if(n->parentNode != this) return;
		n->parentNode = 0;
		children.removeOne(n);
	}
	int indexOf(Node *n) const { return children.indexOf(n); }
	Node *at(int idx) const { return children.at(idx); }
	int count() const { return children.count(); }
	Node *parent() const { return parentNode; }
	T data;

private:
	Node<T> *parentNode;
	QList<Node<T>*> children;
};

template<typename T, int ColCount> class TreeModel : public QAbstractItemModel {
public:
	TreeModel(QObject *parent = 0) : QAbstractItemModel(parent) {
		root = new Node<T>();
	}
	~TreeModel() { delete root; }
	int rowCount(const QModelIndex &parent = QModelIndex()) const {
		return nodeFromIndex(parent)->count();
	}
	int columnCount(const QModelIndex &parent = QModelIndex()) const {
		return ColCount;
	}
	QModelIndex index(int row, int column, const QModelIndex &parent = QModelIndex()) const {
		Node<T> *parentNode = nodeFromIndex(parent);
		if(row < 0 || row >= parentNode->count() || column < 0 || column >= ColCount) return QModelIndex();
		return createIndex(row, column, parentNode->at(row));
	}
	QModelIndex parent(const QModelIndex &child) const {
		Node<T> *childNode = nodeFromIndex(child);
		Node<T> *parentNode = childNode->parent();
		if(parentNode == root) return QModelIndex();
		Node<T> *grandparentNode = parentNode->parent();
		return createIndex(grandparentNode->indexOf(parentNode), 0, parentNode);
	}
	QVariant data(const QModelIndex &index, int role) const {
		qWarning("Reimplement in subclass");
		return QVariant();
	}
protected:
	Node<T>* nodeFromIndex(const QModelIndex &idx) const {
		if(idx.isValid()) return static_cast<Node<T>*>(idx.internalPointer());
		return root;
	}
	Node<T> *root;
};

class Model : public TreeModel<int, 1> {
public:
	Model(QObject *parent = 0) : TreeModel(parent) {}
	QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const {
		if(index.column() != 0) return QVariant();
		if(role != Qt::DisplayRole && role != Qt::EditRole) return QVariant();
		Node<int> *n = nodeFromIndex(index);
		return n->data;
	}
	bool setData(const QModelIndex &index, const QVariant &value, int role = Qt::EditRole) {
		if(index.column() != 0) return false;
		if(role != Qt::DisplayRole && role != Qt::EditRole) return false;
		Node<int> *n = nodeFromIndex(index);
		if(n->data != value.toInt()) {
			n->data = value.toInt();
			emit dataChanged(index, index);
			return true;
		}
		return true;
	}
	void addItem(int dat) {
		beginInsertRows(QModelIndex(), root->count(), root->count());
		Node<int> *n = new Node<int>();
		n->data = dat;
		Node<int> *sn = new Node<int>();
		sn->data = dat*10;
		n->addChild(sn);
		root->addChild(n);
		endInsertRows();
	}
};

class Adder : public QObject {
public:
	Adder(Model *model, int interval = 2000) {
		m_model = model;
		startTimer(interval);
	}
protected:
	void timerEvent(QTimerEvent *) {
		int val = rand() % 100;
		m_model->addItem(val);
	}

private:
	Model *m_model;
};

int main(int argc, char *argv[])
{
	QApplication a(argc, argv);
	QTreeView w;
	Model model;
//	TreeModel<int,1> model;
	w.setModel(&model);
	w.show();
	Adder adder(&model, 1000);
	return a.exec();
}

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