Encoding in the QTableView

mrjj

@ro12man3
say
u define the hash like
QHash<int, QString> Hash;
it means we use int as key and get string as result
so
QString Name=hash[2900];
would give us "Jackson" in name;

please read doc on how it works.
http://doc.qt.io/qt-5/qhash.html

so you would read all lines from text file and insert into hash.

ro12man3

@mrjj woooow thank you! You are the master! :) I understand, very clever idea!

I will try that in the morning.

mrjj

well for 40 lookups its more fun that tons of ifs
if u make a text file with
ID, NAME
like
1000, TOWN
1001, TOWN2
1002, TOWN3

so u need to ( code handwritten fast, not tested. u need to add includes)

QFile file("c:/mynames.txt");
if(!file.open(QIODevice::ReadOnly)) {
QMessageBox::information(0, "error", file.errorString());
}

QTextStream in(&file);
while(!in.atEnd()) {
QString line = in.readLine(); // get a line from file
QStringList fields = line.split(","); <<< KEY point. we ask it to split the text at "," to a list
/// now fields[0] is first part and fields[1] is rest
// so
hash[fields[0].toInt()] = fields[1] ; // store name under key
}

file.close();

ro12man3

@mrjj thank you very much!! I will try that. If I wiil edit this, I will write here the correct code.
Thank you for your helping!

mrjj

@ro12man3
You are very welcome.
One note is that if u read in text lines then
it will be text so u need to convert to int for the key if you
define the hash like that.
QHash<int, QString> Hash;
something like
hash[ fields[0].toInt() ]=xxx
If it gives u grief , let me know as im not 100% sure of syntax as its free writing :)

ro12man3

@mrjj Well, I can extract the second field, but it will be all second fields.

And I have edited the code:

QString MyDelegate::displayText(const QVariant& value, const QLocale& locale) const {
       QString line;
        QFile file("C:/QT/Test text/1.txt");
        if(!file.open(QIODevice::ReadOnly))
               qDebug() << "Error opening file";
        QTextStream in(&file);

        QHash<int, QString> hash;

         while(!in.atEnd()) {
         QString line = in.readLine(); 
         QStringList fields = line.split(","); 
         hash[fields[0].toInt()] = fields[1] ; 
  if (value.toString().compare(fields[0]) == 0)
    return fields[1];
  else
    return value.toString(); 
}
}

And it doesn't work. How to solve that?
It was working when I wrote

 if (value.toString().compare("1000") == 0)
    return "Jackson";

If I write

QMessageBox::information(this, fields[0], fields[1] );

it is working, but it shows ALL values.

mrjj

@ro12man3 said:

And it doesn't work. How to solve that?

You really have to provide more info that that :)
if you insert qDebug() << "f1=" << fields[0] << "f2=" << fields[1];
does it read in the data correctly ? this is critical.
Also you build the hash
hash[fields[0].toInt()] = fields[1] ;
but don't use it. ? You dont use it to look up the text.
QString CityName = hash[value.toInt()];
return CityName;
Also you mix reading in the file with compare value. that is wrong.
You should not read it in displayText as it will then read file each time
it draw that column. that is not so good.
Make Hash a member of the class. (in .h) and just use it
in displayText. then u can read it once and use it over and over.
Read in the text file in the constructor of the delegate;

SGaist

In addition to what @mrjj wrote: make the hash a member of your delegate.

ro12man3

@mrjj said:

You really have to provide more info that that :)
if you insert qDebug() << "f1=" << fields[0] << "f2=" << fields[1];
does it read in the data correctly ? this is critical.

Yes, I can extract this values. I tested that in QMessageBox.
More info... http://rghost.ru/7wFZPWC4v This is the project.
Download link(http://rghost.ru/download/7wFZPWC4v/ccf2cf56d3bbd353e8db12f377907d858f261e23/ccf2cf56d3bbd353e8db12f377907d858f261e23/myfirstviewEDITED.rar)

It's not very difficult code structure, I don't know why it's not working.

SGaist

Hi,

Because it's not buildable as is.

MyDelegate::MyDelegate(QObject *parent)
    : QStyledItemDelegate(parent)
{
    QString line;
    QFile file("1.txt");
    if(file.open(QIODevice::ReadOnly)) {
        QTextStream in(&file);
        while(!in.atEnd()) {
            QString line = in.readLine(); // get a line from file
            QStringList fields = line.split(","); // KEY point. we ask it to split the text at "," to a list
            hash[fields[0].toInt()] = fields[1] ; // store name under key
        }
    } else {
        qDebug() << "Error opening file";
    }
}

// this is the key delegate function!
QString MyDelegate::displayText(const QVariant& value, const QLocale& locale) const {
     return hash.value(value.toInt());
}

[edit: code cleanup SGaist]

mrjj

oh a tad to late :)
https://www.dropbox.com/s/3ajogwsoc7n1zjg/myfirstviewEDITED_hash.zip?dl=0

SGaist

Note that the build problem isn't with the delegate but with the MainWindow missing slot implementation.

@mrjj :-D

ro12man3

@mrjj @SGaist oooohhh guys, thank you!! You are amazing!!!

It's working. !!!

The problem is SOLVED! THANK YOU VERY MUCH!!

ro12man3

@mrjj @SGaist
I started to work and I found one bag.
My table is:
Roberto
Jackson
1002
1
And that's my txt file:
1002,Hello
1,How are you
So the result in the table is
Roberto
Jackson
Hello
How are you

It's good. Correct work.
But if I change 1002 to 10--02 then all const values in the table will become like a second value for 10--02. The result will become:
Hello
Hello
Hello
How are you
You can see that, just edit in table Maria to 10--02 and add 10--02 to txt file. What is that?

mrjj

@ro12man3 said:

10--02

hi
If you change the first field in file to 10--02
it it no longer a valid integer.
Our hash is Int, String
so that mean use int as key and get back string
when we read "10--02", and say toInt() we get 0 or something undefined.

If you need to use a key that is not really a integer. like 10--02, then
you must change the hash to be Qstring, QString and NOT use toInt() when inserting
into hash.
So make sure your text format fits the Hash or strange things will happen :)

ro12man3

@mrjj Ok. It was

// In .h file:
QHash<int, QString> hash;
......
  hash[fields[0].toInt()] = fields[1] ;
......
// In .cpp file:
QString mapped = hash.value(value.toInt());

After editing it's:

// In .h file:
QHash<QString, QString> hash;
......
  hash[fields[0]] = fields[1] ;
......
// In .cpp file:
QString mapped = hash.value(value);

Is it correct?

mrjj

hi
yes, seems fine. good work.
i think you might need
QString mapped = hash.value(value.toString);
as value is variant and hash wants string.

ro12man3

@mrjj Wooow I'm so happy, really :D Thank you :) I will study and study and study :)