Regarding Using QSettings to read INI File

jim_kaiser

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.

Indrajeet

Hi

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

Can anyone explain with example code.

Regards
Indrajeet

jim_kaiser

"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.

Indrajeet

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

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

jim_kaiser

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.

victor wang

@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!

jsulm

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

poojakamshetty

@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.

mrjj

@poojakamshetty
Hi and welcome to the forums

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

poojakamshetty

@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

jsulm

@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?

mrjj

@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 :))

poojakamshetty

@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

poojakamshetty

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

JonB

@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.

poojakamshetty

@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?

mrjj

@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.

poojakamshetty

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

mrjj

@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.