Encoding in the QTableView

mrjj

@ro12man3
ok. the first delegate can be slightly trick if u are not deeply into c++
as it involved subclassing and virtual function override.
looking at samples is a good idea.

ro12man3

@mrjj I have seen the link about star delegate, but I'm not sure how to edit that for me. Can you write simple code, please?
And what to do if I have 40 codes that I will need to change?

mrjj

@ro12man3
hi
Delegates are a bit involved to code so small samples is not so easy.'
The main concept for you would to be override
http://doc.qt.io/qt-5.5/qstyleditemdelegate.html#displayText
so when view ask how to show data , you can then
replace the ID with the correct text.

for 40 codes , you might need a lookup table as pure ifs
if ( ID == 1000) return "CITY";
will be a bit verbose :)

SGaist

Hi,

You should build a hash of your data and use it to map your numbers to your city.

ro12man3

@SGaist if I understand you correctly, I need to use QHash, yes?

mrjj

@ro12man3
hi yes QHash would be fine
http://www.bogotobogo.com/Qt/Qt5_QHash.php

ro12man3

@mrjj thank you very much! But how integrate that with QTableView?

mrjj

@ro12man3
well when u create your delegate object
you also give it a Hash list with the town names.
so in displayText()
it can look up in the list the name to use from the number from DB.

ro12man3

@mrjj unfortunately, it doesn't work. I read that for solving that problem I need to change TableView to TableWidget and use QTableWidgetItem. How to change the numbers in that variant?

mrjj

@ro12man3 said:

How to change the numbers in that variant?

Hi Im not sure what you ask about ?

QTableWidgetItem is not a variant.

ro12man3

@mrjj well... I talk about how to make changing the numbers to text in my tableview(or widget). I wrote

QHash< int, QString> hash;
 hash.insert(100, "Jackson");

and it doesn't change nothing in the table

SGaist

Where's that hash located ?
Did you set your custom QStyledItem delegate on the correct column of your QTableView ?
Are you sure that the volume contains the correct values ?

ro12man3

@SGaist this is the code

void MainWindow::on_pushButton_clicked() // I click and the quiery result is showing in the qtableview
{
QSqlQueryModel * model = new QSqlQueryModel(0);
QHash< int, QString> hash;
 hash.insert(100, "Jackson");
model->setQuery("select city-codes from country");
ui->tableView->setModel(model);
}

SGaist

That hash is destroyed at the end of on_pushButton_clicked

ro12man3

@SGaist so what I need to do for the correct changing values in my tableview?
Where I need to write the QHash function?

SGaist

Either in your QStyledItemDelegate or as @mrjj suggested pass it to the delegate e.g. at construction time.

ro12man3

@SGaist what will be more simple? Cause I don't know how to make that. Sorry about my not big skills in qt

SGaist

In your QStyledItemDelegate, read your file and build the hash with its content. Then in your displayText reimplementation return _hash.value(value.toInt(), tr("Not found"));

mrjj

@ro12man3
hi
Starting with models and view are not best intro to Qt.
They are very powerful but does demand some c++ skills and reading the docs.

Sometimes code is easier to understand so I made u sample with @SGaist help.

It has a list of names and if it sees Lars, it replaced it with BANNED.
For your code, you will use the hash to look up the name from the code.

https://www.dropbox.com/s/vsiqjrr41jhafqo/myfirstview.zip?dl=0

the key points to understand is:
we make a new class to override the default behaviour

class MyDelegate : public QStyledItemDelegate {
public:
MyDelegate(QObject* parent)
: QStyledItemDelegate(parent) {}
virtual QString displayText(const QVariant& value, const QLocale& locale) const;
};

We set this delegate ONLY to the column we need.

ui->tableView->setItemDelegateForColumn(0, new MyDelegate(this));

the displayText is the key function.:

QString MyDelegate::displayText(const QVariant& value, const QLocale& locale) const {
if (value.toString().compare("Lars") == 0) // if found
return "BANNED";
else
return value.toString(); // else just return data unchanged
}

Here u will replace the city-code with names using the hash.

Hope this helps you.

ro12man3

@mrjj ohhh thank you! It works!! Thank you very much.

But I have 40 values that I will need to change(if it will be in quiery result).

I can't write 40 "else if".. "else if"... "else if".... That's unlogic.
I need to write all that values in support *.txt file(or another, the main is a simple format for editing), cause if I will write all that values in the program and then I will need to add new values...That's will be very uncomfortable.

I see the method of the working the function so:
The function is searching the values(from *.txt file) that has a quiery result. If it will find, then it will change to another every value.

But...how make that in reality?