How to modify the data in the model and update the view when new data is received from external?

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My model looks like this:

In parent method i use pointer for parent item but not reference.

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@VRonin @SGaist @JonB : I just debugged to see that after changing the value of the property via delegate does the index in the following code has the same value.

QModelIndex index = createIndex(0, 1, categories_.at(0)->entryAt(0));
    this->setData(index, 11, Qt::EditRole);

But it turns out that the index in the above is just a copy and when delegate changes the value it is not reflected in the index here. I think i am changing at a copy of the property but not the actual one.

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VRonin

Can you show us the code for Delegate::setModelData?

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@VRonin

 void PropertyEditorItemDelegate::setModelData(QWidget *editor, QAbstractItemModel *model, const QModelIndex &index) const {
        const auto currentItem = static_cast<ScenarioPropertyItem *>(index.internalPointer());

        auto setup = [this, &model, &index](auto editor, auto usage) {
            if (editor) {
                usage(editor);
            } else {
                QStyledItemDelegate::setModelData(editor, model, index);
            }
        };

        switch (currentItem->itemType()) {
            case PropertyType::DOUBLE: {
                setup(qobject_cast<QDoubleSpinBox *>(editor), [&index, &model](QDoubleSpinBox *editor) {
                    editor->interpretText();
                    model->setData(index, editor->value(), Qt::EditRole);
                });
                break;
            }
            case PropertyType::INTEGER: {
                setup(qobject_cast<QSpinBox *>(editor), [&index, &model](QSpinBox *editor) {
                    editor->interpretText();
                    model->setData(index, editor->value(), Qt::EditRole);
                });
                break;
            }
            case PropertyType::STRING: {
                setup(qobject_cast<QLineEdit *>(editor), [&index, &model](QLineEdit *editor) { model->setData(index, editor->text(), Qt::EditRole); });
                break;
            }
            case PropertyType::BOOLEAN: {
                setup(qobject_cast<QComboBox *>(editor),
                      [this, &index, &model](QComboBox *editor) { model->setData(index, editor->currentText(), Qt::EditRole); });
                break;
            }
            default:
                QStyledItemDelegate::setModelData(editor, model, index);
                break;
        }
    }

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SGaist

Why are you calling createIndex in onRefreshRoadInfo ?

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@SGaist In onRefereshRoadInfo function i get the new values which has to be shown in the view. So, here I want to update the values, and as i dont have the index's, i create index for every property and call setData to update the values. If this is not correct how should i update the values here?

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@JonB @SGaist @VRonin : Any lead for my problem?

SGaist

Please show more patience, allow at least 24 hours before bumping your own thread. People answering on this forum do it on a voluntary basis and might not live in the same time zone as you.

That said, I stumble upon the QJsonModel project. You might want to check it.

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@SGaist I will keep in mind :). I saw the project and looks like my current implementation looks but, the project does not have the one thing i am looking for i.e. updating of data inside the code i.e. onRefereshRoadInfo.

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How is it possible that even after changing the model data value in a hard way and emitting reset model signals does not refresh the view.

void ScenarioPropertiesModel::onRefreshRoadInfo(const NewData& roadInfo) {
    emit beginResetModel();
    categories_.at(0)->entryAt(0)->setValue(11111);
    emit endResetModel();
}

Could it be that index function implementation is wrong? This is my index implementation:


QModelIndex Model::index(int row, int column, const QModelIndex& parent /*= QModelIndex()*/) const {
    if (!hasIndex(row, column, parent)) {
        return QModelIndex();
    }

    if (!parent.isValid()) {
        return createIndex(row, column, categories_.at(row).get());
    }

    const auto currentCategory = static_cast<CategoryItem*>(parent.internalPointer());
    ScenarioPropertyItem* currentItem = currentCategory->entryAt(row);

    if (currentItem) {
        return createIndex(row, column, currentItem);
    } else {
        return QModelIndex();
    }
}

VRonin

It still not clear to me in what component the problem is. Could you try to remove your custom delegate and see if it updates the values? if it doesn't then it's a model problem but at least we know where to focus

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@VRonin: Hi Ronin, thnx for the reply. Even without delegates it is not working. I believe it lies in model. I am updating a copy of the model but not the model.
Here below, the model pointer is always in the old state, even after changing the values in my model class.

void Delegate::setModelData(QWidget *editor, QAbstractItemModel *model, const QModelIndex &index)

For infor: I have hosted the project in Github: https://github.com/vinayrajputh/qtmodelview

VRonin

@VInay123 said in How to modify the data in the model and update the view when new data is received from external?:

For infor: I have hosted the project in Github: https://github.com/vinayrajputh/qtmodelview

Would have been nice if it compiled. Can you upload the ui and json file too?

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@VRonin : Done.

VRonin

I'm concentrating on the model only at the moment but it works perfectly for me.
The only thing that I would flag is that the json that you provided has all "ReadOnly": true so it won't allow changes unless you change that to false.

Could you try this fork and tell me what is that you expect to happen that is not happening?

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@VRonin: Now there is a function with following signature

void ScenarioPropertiesModel::onRefreshRoadInfo(const NewData& roadInfo) {}

Now i would ask you to set the model data (properties) to the new values present in roadInfo variable(or to a random number) in the above function and display it in the view.

My usecase is that, i will have a street and when user clicks on the street onRefreshRoadInfo will be called with the values which are actually coordinates and these i want to show.

VRonin

So you are confirming that, so far, the fork above is behaving correctly?

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@VRonin : Yes, it works correctly. :)