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Regarding Using QSettings to read INI File



  • Hi All

    I am trying to read INI File using QSettings. Below is my format of INI File & code to read that file

    INI File Format:
    [TAG1]
    key1=value1
    key2=value2
    .
    .
    .
    .
    .
    .
    .

    CODE:
    @QSettings settings("test.ini", QSettings::IniFormat);
    settings.beginGroup("TAG1");
    const QStringList childKeys = settings.childKeys();
    foreach (const QString &childKey, childKeys)
    QString var = settings.value(childKey).toString();
    settings.endGroup();@

    My problem here is I want to retrieve all values & store in some array or List How to do it.
    But as I am retieving values in QString I am able to get only last value.



  • Try using "allKeys":http://doc.qt.nokia.com/stable/qsettings.html#allKeys

    @
    QSettings settings("test.ini", QSettings::IniFormat);
    settings.beginGroup("TAG1");
    QStringList keys = settings.allKeys();
    @



  • Hi Leon

    Thanks for reply,but wat I am looking for is we retrieved all keys
    in QStringList,Likewise I also want all the values of these keys
    inQStringList.So that i can use those values.

    Regadrs
    Indrajeet



  • You mean like:
    @
    QSettings settings("test.ini", QSettings::IniFormat);
    settings.beginGroup("TAG1");
    const QStringList childKeys = settings.childKeys();
    QStringList values;
    foreach (const QString &childKey, childKeys)
    values << settings.value(childKey).toString();
    settings.endGroup();
    @



  • Hi loladiro

    Ya thanks this is wat i required.

    One more thing my INI file has only one key & one value. But while debugging
    cursor enters foreach loop thrice why is it so.

    Below is my INI file contents

    [Shared Folder]
    commonpath=c:\desktop\QT\QTDOC1

    Regards
    Indrajeet



  • The foreach loop is really just a macro used by Qt. And it expands to this (at least on gcc, it's different for other compilers):
    @
    for (QForeachContainer<typeof(container)> container(container);
    !container.brk && container.i != container.e;
    extension ({ ++container.brk; ++container.i; }))
    for (variable = *container.i;; extension ({--container.brk; break;}))
    @
    And this causes the debugger to go through all the steps in the expanded macro, while showing you just the macro (if that makes sense).



  • Hi Loladiro

    So wether foreach loop is slower or faster.
    Is there any other way other than foreach loop
    to retrieve values form QStringList.

    Regards
    Indrajeet



  • Believe me the foreach loop is fast! And it makes it easier shoud you ever change your container e.g. from a QList to a QSet.



  • Hi loladiro

    How to retrieve each value from QStringList which we got from foreach loop
    into QString?

    Regards
    Indrajeet



  • What exactly do you want to do with the values ( I think I can help you better that way)?



  • Perhaps, instead of storing your values in two QStringLists, you would like to store them in a single QHash<QString, QString> ?

    That way, at least you keep your keys and values together in the same container...

    To get them, you could modify the example code from above to something like this:
    @
    QSettings settings("test.ini", QSettings::IniFormat);
    settings.beginGroup("TAG1");
    const QStringList childKeys = settings.childKeys();
    QHash<QString, QString> values;
    foreach (const QString &childKey, childKeys)
    values.insert(childKey, settings.value(childKey).toString());
    settings.endGroup();
    @



  • Hi

    How to handle if INI file is not found.

    Regards
    Indrajeet



  • QSettings::status



  • bq. How to handle if INI file is not found.

    You could handle it directly in the settings since the settings is opened in a read-write mode.

    From Documentation:

    bq. Constructs a QSettings object for accessing the settings stored in the file called fileName, with parent parent. If the file doesn't already exist, it is created.

    Now, the value() function takes a default value.
    @ QVariant value ( const QString & key, const QVariant & defaultValue = QVariant() ) const @

    So, if no setting, then your default value passed is used. This is the way to do it.

    Here's another approach just for kicks..

    From QSetting documentation, on windows, the user path seems to be
    @ %APPDATA% @
    and system path
    @ %COMMON_APPDATA% @
    Not on a windows machine right now, but you could try something like
    @
    QString iniDir = QProcessEnvironment::systemEnvironment ().value("COMMON_APPDATA")
    bool iniExists = QFileInfo(iniDir, "test.ini").exists();
    @
    Then if no settings file, instead of reading the settings.. use default settings, when closing, store the settings into the ini.



  • Hi

    I didnt get How to handle if INI file is not found.

    Can anyone explain with example code.

    Regards
    Indrajeet



  • "QSettings Constructor":http://doc.qt.nokia.com/stable/qsettings.html#QSettings-4

    You don't need to do anything to handle missing file. If the ini filename you pass isn't present Qt will create it. So..

    @ QSettings settings("test.ini", QSettings::IniFormat); @

    Will automatically create the test.ini file, if it doesn't exist.

    Now, in your code to read from settings.
    @ foreach (const QString &childKey, childKeys)
    values.insert(childKey, settings.value(childKey).toString()); @
    You can pass a default argument like
    @ values.insert(childKey, settings.value(childKey, "defaultval").toString()); @
    So that should do for reading the settings.

    When you write the settings back to the ini later on, you will be saving the default values you have read above since there was no ini to read from. I hope thats clear.



  • Hello jim

    Below is my code snippet

    @QSettings settings("test.ini", QSettings::IniFormat);
    settings.beginGroup("TAG1");
    const QStringList childKeys = settings.childKeys();
    foreach (const QString &childKey, childKeys)
    QString var = settings.value(childKey).toString();
    settings.endGroup();@

    You said that if test.ini is not found it will create the new by itself.
    But wat about the contents of the file.As I am looking for TAG1 it is
    crashing there.

    So wat is the solution for this.

    Regards
    Indrajeet



  • Hi All

    If the INI FILE has more TAGS for Example

    INI File Format:
    [TAG1]
    key1=value1
    key2=value2
    .
    .
    .
    .
    .
    [TAG2]
    key3=value3
    key4=value4
    .
    .
    .
    .
    How to collect values of all tags in single List and return that list.

    Regards
    Indrajeet



  • I don't see why it would crash! The beginGroup simply sets the prefix to use for the keys. If your key doesn't exist
    @ settings.value(childKey).toString() @
    will return a empty QVariant(). You can also provide a default value like I have said above.

    For the next question..
    Taking code from others who have answered it above.
    @
    QSettings settings("test.ini", QSettings::IniFormat);
    const QStringList childKeys = settings.allKeys();
    QStringList values;
    foreach (const QString &childKey, childKeys)
    values << settings.value(childKey).toString();
    settings.endGroup();
    @

    I think, you have all the info you need. Try to experiment and debug to see what is going on if there is a problem. And post the offending code.



  • @jim_kaiser
    Hi

    This is my code here
    And i got some error.
    Is there anything i need to fix?

    This is an error here

    Please help!


  • Qt Champions 2019

    @victor-wang Why did you put ; after foreach?
    qDebug() instead of qDebug



  • @andre Hi sir, I tried this method and I am able to read 1 tag values but if I try to read 2nd tag values I am not getting. Can you please help me with this.
    QSettings settings("abc.ini", QSettings::IniFormat);
    settings.beginGroup("tag 1");
    const QStringList childKeys = settings.childKeys();
    QHash<QString,QString>values;
    foreach (const QString &childKey,childKeys)
    values.insert(childKey, settings.value(childKey).toString());
    settings.endGroup();
    qDebug()<<values;
    This was my code for 1 tag(Attributes)
    but for other tag I am not getting
    [tag 1]
    key1=value1
    key2=value2
    key3=value3
    key4=value4
    .
    .
    [tag2]
    key1=value1
    key2=value2
    key3=value3
    key4=value4
    .
    .
    Now how to read this tag2 I am unable to do. Can you pls tell me.
    Thank you.


  • Lifetime Qt Champion

    @poojakamshetty
    Hi and welcome to the forums

    But did you try with
    settings.beginGroup("tag2);
    and then same code otherwise ?



  • @mrjj Hi sir, Yeah I tried settings.beginGroup("tag2"); I am getting the output but my key=values are not coming in order. How can I get in order?
    QSettings settings("abc.ini", QSettings::IniFormat);
    QHash<QString,QString>values;
    settings.beginGroup("tag1");
    QStringList childKeys = settings.childKeys();
    foreach (const QString &childKey,childKeys)
    values.insert(childKey, settings.value(childKey).toString());
    settings.endGroup();
    settings.beginGroup("tag2");
    childKeys = settings.childKeys();
    foreach (const QString &childKey,childKeys)
    values.insert(childKey, settings.value(childKey).toString());
    settings.endGroup();
    qDebug()<<"Key-value pair:"<<values;
    output: Key-value pair: QHash(("a2", "c2")("d", "m")("k", "v")("d2", "m2")("a", "c")("k2", "v2"))
    order of my mini file is
    [tag1]
    k=v
    a=c
    d=m
    [tag2]
    k2=v2
    a2=c2
    d2=m2
    Can you tell how to get in order


  • Qt Champions 2019

    @poojakamshetty Please check documentation: https://doc.qt.io/qt-5/qhash.html "With QHash, the items are arbitrarily ordered". With QMap data is sorted by key.
    Why do you need same order in the container?


  • Lifetime Qt Champion

    @poojakamshetty
    Hi
    The out of order comes from
    QHash<QString, QString>values;
    Is what we call unordered
    You can use QMap instead
    QMap<QString, QString>values;

    and then it should come in the expected order.

    (meh i type too slow :))



  • @jsulm yeah understood. Thank you. But I want in the same order in the container because I can access it easily later. But in the same order, I am not getting my output



  • @mrjj I tried this but I am not getting my output as expected order.



  • @poojakamshetty

    But in the same order, I am not getting my output

    I wonder what that means? Have you changed QHash over to QMap? QMap is ordered, but only by key name (i.e. alphabetically). If you retrieve them from the file in a particular order, you will have to use a list/array instead if you wish to retain that particular order.



  • @JonB Got it,thank you. I am getting in alphabetical order when I am using QMap. My Requirement is to get in the order the same as my .ini file. What should I do?


  • Lifetime Qt Champion

    @poojakamshetty
    hi
    Well store them in a list instead. that will store them as added but you lose
    the ability to lookup by key but maybe thats fine.



  • @mrjj Hi,
    If I store them in a list I think I won't get the output as key-value pair right?


  • Lifetime Qt Champion

    @poojakamshetty
    Hi
    Not if you only store a string but you could easily just do
    QVector<QPair<QString, QString>> list;
    or a similar structure to store both key and value in the same list.



  • This post is deleted!


  • @mrjj Hi
    Okay, Got it Thank you.
    I have a doubt. In the container, the values can be stored in any order or if they are not in the order as .ini file will that be any problem later?


  • Lifetime Qt Champion

    @poojakamshetty
    Hi
    They will be stored in same order as you add them so if you add them in the order you read them it should be as you want. (same order as in ini file)



  • @poojakamshetty

    if they are not in the order as .ini file will that be any problem later?

    The ini file/QSettings does not care about the order of entries. Only you seem to want this:

    My Requirement is to get in the order the same as my .ini file.

    Why do you even need this?



  • This post is deleted!


  • @poojakamshetty
    It helps if you use code tags for posting this here.

    values.insert(childKey, settings.value(childKey).toString());

    Don't you mean:

    QVector<QPair<QString, QString>> values;
    ...
    values.insert(i, QPair<QString, QString>(childKey, settings.value(childKey).toString()));
    

    ?

    Define yourself a type for QPair<QString, QString> and this will read easier.


  • Lifetime Qt Champion

    Hi,

    Since you really want a specific order, wouldn't it be simpler to sort your container after loading it with data ? That way you would be a bit less depending on the storage format.


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