How to get Json value from an api and display it in a GUI

[mrjj]

Hi
@MehdiMak96
the value variable is in small letters
QJsonValue value = obj.value(QString("+name+"));
but error shows as captital first.
use of undeclared identifier 'Value'
Are they written the same ?

Is the task, to read the data associated with the QString &arg1

{
   "data":{
      "10041":{
         "ags":"10041",
         "name":"Regionalverband Saarbrücken",
         "county":"LK Stadtverband Saarbrücken",
         "state":"Saarland",
         "population":328714,
         "cases":15789,
         "deaths":466,
         "casesPerWeek":24,
         "deathsPerWeek":0,
         "stateAbbreviation":"SL",
         "recovered":15257,
         "weekIncidence":7.301179748961103,

Should you not then read the data file once, instead of each time the user chooses something in the Combobox ?

do you use the "10041" id to look it up or how should it work ?

[MehdiMak96]

@Christian-Ehrlicher @JonB

In this line I'm Getting the error

his->ui->textBrowser->setText(value);

the error:

error: no viable conversion from 'QJsonValue' to 'const QString'

@mrjj

The whole idea is to let the user to choose whatever city in the combobox and show him the "weekIncidence" in that city in a text browser .
I just figured another problem to right a code that can only read the "weekIncidence" :/

[JonB]

@MehdiMak96 said in How to get Json value from an api and display it in a GUI:

error: no viable conversion from 'QJsonValue' to 'const QString'

But you wrote earlier that there error message was:

use of undeclared identifier 'Value'

? And got everybody to look for that....

[JonB]

@MehdiMak96
Anyway....

QJsonValue value = obj.value(QString("+name+"));
this->ui->textBrowser->setText(value);

error: no viable conversion from 'QJsonValue' to 'const QString'

setText(), requires a string. value is type QJsonValue. You already know that's not a string and how to convert it because you have

qDebug() << " value is" << value.toString();;

[MehdiMak96]

@JonB
yeah I'm sorry that is because my line was out side the bracket in my computer

like this :

      });
  this->ui->textBrowser->setText(value);
    }

}

[JonB]

@MehdiMak96
OK, but that's not in the code you showed. And you didn't say anything when you discovered it so we knew.

Anyway for that new error your post crossed with mine, see my previous post above.

[MehdiMak96]

Thanks the error is gone but it showed nothing on the text browser

[JonB]

@MehdiMak96
That's down to you. Only you know what is the JSON you are reading. You might put more debugging output in your code, or run it in debugger.

Also if you have not acted on what has been said about the scope of the QNetworkAccessManager m_manager; you may have problems. But you'll know that from your debugging.

[MehdiMak96]

@JonB but i have no clue what this means

    // if in mainwindow. make sure m_manager lives in .h as member. else it wont work. ( death by scope)
      QNetworkAccessManager m_manager;

can you please explain it to me

[mrjj]

@MehdiMak96

Hi
I wrote that comment.
It means
QNetworkAccessManager m_manager; here is a local variable.
Those are deleted as soon a function ends.
QNetworkAccessManager is asynchronous which means the m_manager might be deleted before
the QNetworkReply::finished is fired.

So its better to move it to part of Corona_Aktuell class.
That is to put it in the .h inside the class. as a class member.

Also regarding your json parsing.
Do note that the data holding class (the cites) is inside an object called
Data. so the current code might be in the wrong json class and hence return nothing
for "name" as that one level deeper.

Is this school task ? Im asking to know how much we can help without breaking the rules.

[JonB]

@MehdiMak96
QNetworkAccessManager m_manager has to "persist"/"be in existence"/"not go out of scope" until after the slot you attached to the reply's finished signal has completed.

In an earlier post I made a suggestion as to what you could do about it.

[MehdiMak96]

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