QSettings¶

PyQt5.QtCore.QSettings: Inherits from QObject.

Description¶

The QSettings class provides persistent platform-independent application settings.

Users normally expect an application to remember its settings (window sizes and positions, options, etc.) across sessions. This information is often stored in the system registry on Windows, and in property list files on macOS and iOS. On Unix systems, in the absence of a standard, many applications (including the KDE applications) use INI text files.

QSettings is an abstraction around these technologies, enabling you to save and restore application settings in a portable manner. It also supports custom storage formats.

QSettings’s API is based on QVariant, allowing you to save most value-based types, such as QString, QRect, and QImage, with the minimum of effort.

If all you need is a non-persistent memory-based structure, consider using QMap<QString, QVariant> instead.

Basic Usage¶

When creating a QSettings object, you must pass the name of your company or organization as well as the name of your application. For example, if your product is called Star Runner and your company is called MySoft, you would construct the QSettings object as follows:

#     QSettings settings("MySoft", "Star Runner");

QSettings objects can be created either on the stack or on the heap (i.e. using new). Constructing and destroying a QSettings object is very fast.

If you use QSettings from many places in your application, you might want to specify the organization name and the application name using setOrganizationName() and setApplicationName(), and then use the default QSettings constructor:

#     QCoreApplication::setOrganizationName("MySoft");

#     QCoreApplication::setOrganizationDomain("mysoft.com");

#     QCoreApplication::setApplicationName("Star Runner");

#     QSettings settings;

(Here, we also specify the organization’s Internet domain. When the Internet domain is set, it is used on macOS and iOS instead of the organization name, since macOS and iOS applications conventionally use Internet domains to identify themselves. If no domain is set, a fake domain is derived from the organization name. See the Platform-Specific Notes below for details.)

QSettings stores settings. Each setting consists of a QString that specifies the setting’s name (the key) and a QVariant that stores the data associated with the key. To write a setting, use setValue(). For example:

#     settings.setValue("editor/wrapMargin", 68);

If there already exists a setting with the same key, the existing value is overwritten by the new value. For efficiency, the changes may not be saved to permanent storage immediately. (You can always call sync() to commit your changes.)

You can get a setting’s value back using value():

#     int margin = settings.value("editor/wrapMargin").toInt();

If there is no setting with the specified name, QSettings returns a null QVariant (which can be converted to the integer 0). You can specify another default value by passing a second argument to value():

#     int margin = settings.value("editor/wrapMargin", 80).toInt();

To test whether a given key exists, call contains(). To remove the setting associated with a key, call remove(). To obtain the list of all keys, call allKeys(). To remove all keys, call clear().

QVariant and GUI Types¶

Because QVariant is part of the Qt Core module, it cannot provide conversion functions to data types such as QColor, QImage, and QPixmap, which are part of Qt GUI. In other words, there is no toColor(), toImage(), or toPixmap() functions in QVariant.

Instead, you can use the value() or the qVariantValue() template function. For example:

# QSettings settings("MySoft", "Star Runner");
# QColor color = settings.value("DataPump/bgcolor").value<QColor>();

The inverse conversion (e.g., from QColor to QVariant) is automatic for all data types supported by QVariant, including GUI-related types:

# QSettings settings("MySoft", "Star Runner");
# QColor color = palette().background().color();
# settings.setValue("DataPump/bgcolor", color);

Custom types registered using qRegisterMetaType() and qRegisterMetaTypeStreamOperators() can be stored using QSettings.

Section and Key Syntax¶

Setting keys can contain any Unicode characters. The Windows registry and INI files use case-insensitive keys, whereas the CFPreferences API on macOS and iOS uses case-sensitive keys. To avoid portability problems, follow these simple rules:

Always refer to the same key using the same case. For example, if you refer to a key as “text fonts” in one place in your code, don’t refer to it as “Text Fonts” somewhere else.
Avoid key names that are identical except for the case. For example, if you have a key called “MainWindow”, don’t try to save another key as “mainwindow”.
Do not use slashes (‘/’ and ‘') in section or key names; the backslash character is used to separate sub keys (see below). On windows ‘' are converted by QSettings to ‘/’, which makes them identical.

You can form hierarchical keys using the ‘/’ character as a separator, similar to Unix file paths. For example:

#     settings.setValue("mainwindow/size", win->size());

#     settings.setValue("mainwindow/fullScreen", win->isFullScreen());

#     settings.setValue("outputpanel/visible", panel->isVisible());

If you want to save or restore many settings with the same prefix, you can specify the prefix using beginGroup() and call endGroup() at the end. Here’s the same example again, but this time using the group mechanism:

#     settings.beginGroup("mainwindow");
#     settings.setValue("size", win->size());
#     settings.setValue("fullScreen", win->isFullScreen());
#     settings.endGroup();

#     settings.beginGroup("outputpanel");
#     settings.setValue("visible", panel->isVisible());
#     settings.endGroup();

If a group is set using beginGroup(), the behavior of most functions changes consequently. Groups can be set recursively.

In addition to groups, QSettings also supports an “array” concept. See beginReadArray() and beginWriteArray() for details.

Fallback Mechanism¶

Let’s assume that you have created a QSettings object with the organization name MySoft and the application name Star Runner. When you look up a value, up to four locations are searched in that order:

a user-specific location for the Star Runner application
a user-specific location for all applications by MySoft
a system-wide location for the Star Runner application
a system-wide location for all applications by MySoft

(See Platform-Specific Notes below for information on what these locations are on the different platforms supported by Qt.)

If a key cannot be found in the first location, the search goes on in the second location, and so on. This enables you to store system-wide or organization-wide settings and to override them on a per-user or per-application basis. To turn off this mechanism, call setFallbacksEnabled()(false).

Although keys from all four locations are available for reading, only the first file (the user-specific location for the application at hand) is accessible for writing. To write to any of the other files, omit the application name and/or specify QSettings::SystemScope (as opposed to QSettings::UserScope, the default).

Let’s see with an example:

#     QSettings obj1("MySoft", "Star Runner");

#     QSettings obj2("MySoft");
#     QSettings obj3(QSettings::SystemScope, "MySoft", "Star Runner");
#     QSettings obj4(QSettings::SystemScope, "MySoft");

The table below summarizes which QSettings objects access which location. “X” means that the location is the main location associated to the QSettings object and is used both for reading and for writing; “o” means that the location is used as a fallback when reading.

Locations	`obj1`	`obj2`	`obj3`	`obj4`
User, Application	X
User, Organization	o	X
System, Application	o		X
System, Organization	o	o	o	X

The beauty of this mechanism is that it works on all platforms supported by Qt and that it still gives you a lot of flexibility, without requiring you to specify any file names or registry paths.

If you want to use INI files on all platforms instead of the native API, you can pass QSettings::IniFormat as the first argument to the QSettings constructor, followed by the scope, the organization name, and the application name:

#     QSettings settings(QSettings::IniFormat, QSettings::UserScope,
#                        "MySoft", "Star Runner");

The Settings Editor example lets you experiment with different settings location and with fallbacks turned on or off.

Restoring the State of a GUI Application¶

QSettings is often used to store the state of a GUI application. The following example illustrates how to use QSettings to save and restore the geometry of an application’s main window.

# void MainWindow::writeSettings()
# {
#     QSettings settings("Moose Soft", "Clipper");

#     settings.beginGroup("MainWindow");
#     settings.setValue("size", size());
#     settings.setValue("pos", pos());
#     settings.endGroup();
# }

# void MainWindow::readSettings()
# {
#     QSettings settings("Moose Soft", "Clipper");

#     settings.beginGroup("MainWindow");
#     resize(settings.value("size", QSize(400, 400)).toSize());
#     move(settings.value("pos", QPoint(200, 200)).toPoint());
#     settings.endGroup();
# }

See Window Geometry for a discussion on why it is better to call resize() and move() rather than setGeometry() to restore a window’s geometry.

The readSettings() and writeSettings() functions must be called from the main window’s constructor and close event handler as follows:

# MainWindow::MainWindow()
# {

#     readSettings();

# }

# void MainWindow::closeEvent(QCloseEvent *event)
# {
#     if (userReallyWantsToQuit()) {
#         writeSettings();
#         event->accept();
#     } else {
#         event->ignore();
#     }
# }

See the Application example for a self-contained example that uses QSettings.

Accessing Settings from Multiple Threads or Processes Simultaneously¶

QSettings is reentrant. This means that you can use distinct QSettings object in different threads simultaneously. This guarantee stands even when the QSettings objects refer to the same files on disk (or to the same entries in the system registry). If a setting is modified through one QSettings object, the change will immediately be visible in any other QSettings objects that operate on the same location and that live in the same process.

QSettings can safely be used from different processes (which can be different instances of your application running at the same time or different applications altogether) to read and write to the same system locations, provided certain conditions are met. For QSettings::IniFormat, it uses advisory file locking and a smart merging algorithm to ensure data integrity. The condition for that to work is that the writeable configuration file must be a regular file and must reside in a directory that the current user can create new, temporary files in. If that is not the case, then one must use setAtomicSyncRequired() to turn the safety off.

Note that sync() imports changes made by other processes (in addition to writing the changes from this QSettings).

Platform-Specific Notes¶

Locations Where Application Settings Are Stored¶

As mentioned in the Fallback Mechanism section, QSettings stores settings for an application in up to four locations, depending on whether the settings are user-specific or system-wide and whether the settings are application-specific or organization-wide. For simplicity, we’re assuming the organization is called MySoft and the application is called Star Runner.

On Unix systems, if the file format is NativeFormat, the following files are used by default:

$HOME/.config/MySoft/Star Runner.conf (Qt for Embedded Linux: $HOME/Settings/MySoft/Star Runner.conf)
$HOME/.config/MySoft.conf (Qt for Embedded Linux: $HOME/Settings/MySoft.conf)
for each directory <dir> in $XDG_CONFIG_DIRS: <dir>/MySoft/Star Runner.conf
for each directory <dir> in $XDG_CONFIG_DIRS: <dir>/MySoft.conf

Note: If XDG_CONFIG_DIRS is unset, the default value of /etc/xdg is used.

On macOS versions 10.2 and 10.3, these files are used by default:

$HOME/Library/Preferences/com.MySoft.Star Runner.plist
$HOME/Library/Preferences/com.MySoft.plist
/Library/Preferences/com.MySoft.Star Runner.plist
/Library/Preferences/com.MySoft.plist

On Windows, NativeFormat settings are stored in the following registry paths:

HKEY_CURRENT_USER\Software\MySoft\Star Runner
HKEY_CURRENT_USER\Software\MySoft\OrganizationDefaults
HKEY_LOCAL_MACHINE\Software\MySoft\Star Runner
HKEY_LOCAL_MACHINE\Software\MySoft\OrganizationDefaults

Note: On Windows, for 32-bit programs running in WOW64 mode, settings are stored in the following registry path: HKEY_LOCAL_MACHINE\Software\WOW6432node.

If the file format is NativeFormat, this is “Settings/MySoft/Star Runner.conf” in the application’s home directory.

If the file format is IniFormat, the following files are used on Unix, macOS, and iOS:

$HOME/.config/MySoft/Star Runner.ini (Qt for Embedded Linux: $HOME/Settings/MySoft/Star Runner.ini)
$HOME/.config/MySoft.ini (Qt for Embedded Linux: $HOME/Settings/MySoft.ini)
for each directory <dir> in $XDG_CONFIG_DIRS: <dir>/MySoft/Star Runner.ini
for each directory <dir> in $XDG_CONFIG_DIRS: <dir>/MySoft.ini

Note: If XDG_CONFIG_DIRS is unset, the default value of /etc/xdg is used.

On Windows, the following files are used:

FOLDERID_RoamingAppData\MySoft\Star Runner.ini
FOLDERID_RoamingAppData\MySoft.ini
FOLDERID_ProgramData\MySoft\Star Runner.ini
FOLDERID_ProgramData\MySoft.ini

The identifiers prefixed by FOLDERID_ are special item ID lists to be passed to the Win32 API function SHGetKnownFolderPath() to obtain the corresponding path.

FOLDERID_RoamingAppData usually points to C:\Users\\ *User Name*\\AppData\\Roaming, also shown by the environment variable %APPDATA%.

FOLDERID_ProgramData usually points to C:\ProgramData.

If the file format is IniFormat, this is “Settings/MySoft/Star Runner.ini” in the application’s home directory.

The paths for the .ini and .conf files can be changed using setPath(). On Unix, macOS, and iOS the user can override them by setting the XDG_CONFIG_HOME environment variable; see setPath() for details.

Accessing INI and .plist Files Directly¶

Sometimes you do want to access settings stored in a specific file or registry path. On all platforms, if you want to read an INI file directly, you can use the QSettings constructor that takes a file name as first argument and pass QSettings::IniFormat as second argument. For example:

# QSettings settings("/home/petra/misc/myapp.ini",
#                    QSettings::IniFormat);

You can then use the QSettings object to read and write settings in the file.

On macOS and iOS, you can access property list .plist files by passing QSettings::NativeFormat as second argument. For example:

# QSettings settings("/Users/petra/misc/myapp.plist",
#                    QSettings::NativeFormat);

Accessing the Windows Registry Directly¶

On Windows, QSettings lets you access settings that have been written with QSettings (or settings in a supported format, e.g., string data) in the system registry. This is done by constructing a QSettings object with a path in the registry and QSettings::NativeFormat.

For example:

# QSettings settings("HKEY_CURRENT_USER\\Software\\Microsoft\\Office",
#                    QSettings::NativeFormat);

All the registry entries that appear under the specified path can be read or written through the QSettings object as usual (using forward slashes instead of backslashes). For example:

# settings.setValue("11.0/Outlook/Security/DontTrustInstalledFiles", 0);

Note that the backslash character is, as mentioned, used by QSettings to separate subkeys. As a result, you cannot read or write windows registry entries that contain slashes or backslashes; you should use a native windows API if you need to do so.

Accessing Common Registry Settings on Windows¶

On Windows, it is possible for a key to have both a value and subkeys. Its default value is accessed by using “Default” or “.” in place of a subkey:

# settings.setValue("HKEY_CURRENT_USER\\MySoft\\Star Runner\\Galaxy", "Milkyway");
# settings.setValue("HKEY_CURRENT_USER\\MySoft\\Star Runner\\Galaxy\\Sun", "OurStar");
# settings.value("HKEY_CURRENT_USER\\MySoft\\Star Runner\\Galaxy\\Default"); // returns "Milkyway"

On other platforms than Windows, “Default” and “.” would be treated as regular subkeys.

Platform Limitations¶

While QSettings attempts to smooth over the differences between the different supported platforms, there are still a few differences that you should be aware of when porting your application:

The Windows system registry has the following limitations: A subkey may not exceed 255 characters, an entry’s value may not exceed 16,383 characters, and all the values of a key may not exceed 65,535 characters. One way to work around these limitations is to store the settings using the IniFormat instead of the NativeFormat.
On Windows, when the Windows system registry is used, QSettings does not preserve the original type of the value. Therefore, the type of the value might change when a new value is set. For example, a value with type REG_EXPAND_SZ will change to REG_SZ.
On macOS and iOS, allKeys() will return some extra keys for global settings that apply to all applications. These keys can be read using value() but cannot be changed, only shadowed. Calling setFallbacksEnabled()(false) will hide these global settings.
On macOS and iOS, the CFPreferences API used by QSettings expects Internet domain names rather than organization names. To provide a uniform API, QSettings derives a fake domain name from the organization name (unless the organization name already is a domain name, e.g. OpenOffice.org). The algorithm appends “.com” to the company name and replaces spaces and other illegal characters with hyphens. If you want to specify a different domain name, call setOrganizationDomain(), setOrganizationName(), and setApplicationName() in your main() function and then use the default QSettings constructor. Another solution is to use preprocessor directives, for example:
```
# #ifdef Q_OS_MAC
#     QSettings settings("grenoullelogique.fr", "Squash");
# #else
#     QSettings settings("Grenoulle Logique", "Squash");
# #endif
```
On macOS, permissions to access settings not belonging to the current user (i.e. SystemScope) have changed with 10.7 (Lion). Prior to that version, users having admin rights could access these. For 10.7 and 10.8 (Mountain Lion), only root can. However, 10.9 (Mavericks) changes that rule again but only for the native format (plist files).

Enums¶

Format

TODO

Member	Value	Description
IniFormat	TODO	TODO
InvalidFormat	TODO	TODO
NativeFormat	TODO	TODO

Scope

TODO

Member	Value	Description
SystemScope	TODO	TODO
UserScope	TODO	TODO

Status

The following status values are possible:

See also

status().

Member	Value	Description
AccessError	1	An access error occurred (e.g. trying to write to a read-only file).
FormatError	2	A format error occurred (e.g. loading a malformed INI file).
NoError	0	No error occurred.

Methods¶

__init__(parent: QObject = None)

Constructs a QSettings object for accessing settings of the application and organization set previously with a call to setOrganizationName(), setOrganizationDomain(), and setApplicationName().

The scope is QSettings::UserScope and the format is defaultFormat() (QSettings::NativeFormat by default). Use setDefaultFormat() before calling this constructor to change the default format used by this constructor.

The code

# QSettings settings("Moose Soft", "Facturo-Pro");

is equivalent to

# QCoreApplication::setOrganizationName("Moose Soft");
# QCoreApplication::setApplicationName("Facturo-Pro");
# QSettings settings;

If setOrganizationName() and setApplicationName() has not been previously called, the QSettings object will not be able to read or write any settings, and status() will return AccessError.

On macOS and iOS, if both a name and an Internet domain are specified for the organization, the domain is preferred over the name. On other platforms, the name is preferred over the domain.

__init__(Scope, parent: QObject = None): TODO

__init__(str, application: str = '', parent: QObject = None): TODO

__init__(str, Format, parent: QObject = None): TODO

__init__(Scope, str, application: str = '', parent: QObject = None): TODO

__init__(Format, Scope, str, application: str = '', parent: QObject = None): TODO

allKeys() → List[str]

Returns a list of all keys, including subkeys, that can be read using the QSettings object.

Example:

# QSettings settings;
# settings.setValue("fridge/color", QColor(Qt::white));
# settings.setValue("fridge/size", QSize(32, 96));
# settings.setValue("sofa", true);
# settings.setValue("tv", false);

# QStringList keys = settings.allKeys();
# // keys: ["fridge/color", "fridge/size", "sofa", "tv"]

If a group is set using beginGroup(), only the keys in the group are returned, without the group prefix:

# settings.beginGroup("fridge");
# keys = settings.allKeys();
# // keys: ["color", "size"]

See also

childGroups(), childKeys().

applicationName() → str: Returns the application name used for storing the settings.

See also

applicationName(), format(), scope(), organizationName().

beginGroup(str)

Appends prefix to the current group.

The current group is automatically prepended to all keys specified to QSettings. In addition, query functions such as childGroups(), childKeys(), and allKeys() are based on the group. By default, no group is set.

Groups are useful to avoid typing in the same setting paths over and over. For example:

# settings.beginGroup("mainwindow");
# settings.setValue("size", win->size());
# settings.setValue("fullScreen", win->isFullScreen());
# settings.endGroup();

# settings.beginGroup("outputpanel");
# settings.setValue("visible", panel->isVisible());
# settings.endGroup();

This will set the value of three settings:

mainwindow/size
mainwindow/fullScreen
outputpanel/visible

Call endGroup() to reset the current group to what it was before the corresponding call. Groups can be nested.

See also

endGroup(), group().

beginReadArray(str) → int

Adds prefix to the current group and starts reading from an array. Returns the size of the array.

Example:

# struct Login {
#     QString userName;
#     QString password;
# };
# QList<Login> logins;
# ...

# QSettings settings;
# int size = settings.beginReadArray("logins");
# for (int i = 0; i < size; ++i) {
#     settings.setArrayIndex(i);
#     Login login;
#     login.userName = settings.value("userName").toString();
#     login.password = settings.value("password").toString();
#     logins.append(login);
# }
# settings.endArray();

Use beginWriteArray() to write the array in the first place.

beginWriteArray(str, size: int = -1)

Adds prefix to the current group and starts writing an array of size size. If size is -1 (the default), it is automatically determined based on the indexes of the entries written.

If you have many occurrences of a certain set of keys, you can use arrays to make your life easier. For example, let’s suppose that you want to save a variable-length list of user names and passwords. You could then write:

# struct Login {
#     QString userName;
#     QString password;
# };
# QList<Login> logins;
# ...

# QSettings settings;
# settings.beginWriteArray("logins");
# for (int i = 0; i < logins.size(); ++i) {
#     settings.setArrayIndex(i);
#     settings.setValue("userName", list.at(i).userName);
#     settings.setValue("password", list.at(i).password);
# }
# settings.endArray();

The generated keys will have the form

logins/size
logins/1/userName
logins/1/password
logins/2/userName
logins/2/password
logins/3/userName
logins/3/password
…

To read back an array, use beginReadArray().

childGroups() → List[str]

Returns a list of all key top-level groups that contain keys that can be read using the QSettings object.

Example:

# QSettings settings;
# settings.setValue("fridge/color", QColor(Qt::white));
# settings.setValue("fridge/size", QSize(32, 96));
# settings.setValue("sofa", true);
# settings.setValue("tv", false);

# QStringList groups = settings.childGroups();
# // groups: ["fridge"]

If a group is set using beginGroup(), the first-level keys in that group are returned, without the group prefix.

# settings.beginGroup("fridge");
# groups = settings.childGroups();
# // groups: []

You can navigate through the entire setting hierarchy using childKeys() and recursively.

See also

childKeys(), allKeys().

childKeys() → List[str]

Returns a list of all top-level keys that can be read using the QSettings object.

Example:

# QSettings settings;
# settings.setValue("fridge/color", QColor(Qt::white));
# settings.setValue("fridge/size", QSize(32, 96));
# settings.setValue("sofa", true);
# settings.setValue("tv", false);

# QStringList keys = settings.childKeys();
# // keys: ["sofa", "tv"]

If a group is set using beginGroup(), the top-level keys in that group are returned, without the group prefix:

# settings.beginGroup("fridge");
# keys = settings.childKeys();
# // keys: ["color", "size"]

You can navigate through the entire setting hierarchy using and childGroups() recursively.

See also

childGroups(), allKeys().

clear()

Removes all entries in the primary location associated to this QSettings object.

Entries in fallback locations are not removed.

If you only want to remove the entries in the current group(), use remove(“”) instead.

See also

remove(), setFallbacksEnabled().

contains(str) → bool

Returns true if there exists a setting called key; returns false otherwise.

If a group is set using beginGroup(), key is taken to be relative to that group.

Note that the Windows registry and INI files use case-insensitive keys, whereas the CFPreferences API on macOS and iOS uses case-sensitive keys. To avoid portability problems, see the Section and Key Syntax rules.

See also

value(), setValue().

@staticmethod defaultFormat() → Format: Returns default file format used for storing settings for the QSettings(QObject *) constructor. If no default format is set, QSettings::NativeFormat is used.

See also

setDefaultFormat(), format().

endArray(): Closes the array that was started using beginReadArray() or beginWriteArray().

See also

beginReadArray(), beginWriteArray().

endGroup()

Resets the group to what it was before the corresponding beginGroup() call.

Example:

# settings.beginGroup("alpha");
# // settings.group() == "alpha"

# settings.beginGroup("beta");
# // settings.group() == "alpha/beta"

# settings.endGroup();
# // settings.group() == "alpha"

# settings.endGroup();
# // settings.group() == ""

See also

beginGroup(), group().

event(QEvent) → bool: TODO

fallbacksEnabled() → bool

Returns true if fallbacks are enabled; returns false otherwise.

By default, fallbacks are enabled.

See also

setFallbacksEnabled().

fileName() → str

Returns the path where settings written using this QSettings object are stored.

On Windows, if the format is QSettings::NativeFormat, the return value is a system registry path, not a file path.

See also

isWritable(), format().

format() → Format: Returns the format used for storing the settings.

See also

defaultFormat(), fileName(), scope(), organizationName(), applicationName().

group() → str: Returns the current group.

See also

beginGroup(), endGroup().

iniCodec() → QTextCodec: Returns the codec that is used for accessing INI files. By default, no codec is used, so a null pointer is returned.

See also

setIniCodec().

isAtomicSyncRequired() → bool

Returns true if QSettings is only allowed to perform atomic saving and reloading (synchronization) of the settings. Returns false if it is allowed to save the settings contents directly to the configuration file.

The default is true.

See also

setAtomicSyncRequired(), QSaveFile.

isWritable() → bool

Returns true if settings can be written using this QSettings object; returns false otherwise.

One reason why might return false is if QSettings operates on a read-only file.

Warning: This function is not perfectly reliable, because the file permissions can change at any time.

See also

fileName(), status(), sync().

organizationName() → str: Returns the organization name used for storing the settings.

See also

organizationName(), format(), scope(), applicationName().

remove(str)

Removes the setting key and any sub-settings of key.

Example:

# QSettings settings;
# settings.setValue("ape");
# settings.setValue("monkey", 1);
# settings.setValue("monkey/sea", 2);
# settings.setValue("monkey/doe", 4);

# settings.remove("monkey");
# QStringList keys = settings.allKeys();
# // keys: ["ape"]

Be aware that if one of the fallback locations contains a setting with the same key, that setting will be visible after calling .

If key is an empty string, all keys in the current group() are removed. For example:

# QSettings settings;
# settings.setValue("ape");
# settings.setValue("monkey", 1);
# settings.setValue("monkey/sea", 2);
# settings.setValue("monkey/doe", 4);

# settings.beginGroup("monkey");
# settings.remove("");
# settings.endGroup();

# QStringList keys = settings.allKeys();
# // keys: ["ape"]

Note that the Windows registry and INI files use case-insensitive keys, whereas the CFPreferences API on macOS and iOS uses case-sensitive keys. To avoid portability problems, see the Section and Key Syntax rules.

See also

setValue(), value(), contains().

scope() → Scope: Returns the scope used for storing the settings.

See also

format(), organizationName(), applicationName().

setArrayIndex(int)

Sets the current array index to i. Calls to functions such as setValue(), value(), remove(), and contains() will operate on the array entry at that index.

You must call beginReadArray() or beginWriteArray() before you can call this function.

setAtomicSyncRequired(bool)

Configures whether QSettings is required to perform atomic saving and reloading (synchronization) of the settings. If the enable argument is true (the default), sync() will only perform synchronization operations that are atomic. If this is not possible, sync() will fail and status() will be an error condition.

Setting this property to false will allow QSettings to write directly to the configuration file and ignore any errors trying to lock it against other processes trying to write at the same time. Because of the potential for corruption, this option should be used with care, but is required in certain conditions, like a QSettings::IniFormat configuration file that exists in an otherwise non-writeable directory or NTFS Alternate Data Streams.

See QSaveFile for more information on the feature.

See also

isAtomicSyncRequired(), QSaveFile.

@staticmethod setDefaultFormat(Format): TODO

setFallbacksEnabled(bool)

Sets whether fallbacks are enabled to b.

By default, fallbacks are enabled.

See also

fallbacksEnabled().

setIniCodec(QTextCodec)

Sets the codec for accessing INI files (including .conf files on Unix) to codec. The codec is used for decoding any data that is read from the INI file, and for encoding any data that is written to the file. By default, no codec is used, and non-ASCII characters are encoded using standard INI escape sequences.

Warning: The codec must be set immediately after creating the QSettings object, before accessing any data.

See also

iniCodec().

setIniCodec(str)

This is an overloaded function.

Sets the codec for accessing INI files (including .conf files on Unix) to the QTextCodec for the encoding specified by codecName. Common values for codecName include “ISO 8859-1”, “UTF-8”, and “UTF-16”. If the encoding isn’t recognized, nothing happens.

See also

codecForName().

@staticmethod setPath(Format, Scope, str): TODO

setValue(str, Any)

Sets the value of setting key to value. If the key already exists, the previous value is overwritten.

Note that the Windows registry and INI files use case-insensitive keys, whereas the CFPreferences API on macOS and iOS uses case-sensitive keys. To avoid portability problems, see the Section and Key Syntax rules.

Example:

# QSettings settings;
# settings.setValue("interval", 30);
# settings.value("interval").toInt();     // returns 30

# settings.setValue("interval", 6.55);
# settings.value("interval").toDouble();  // returns 6.55

See also

value(), remove(), contains().

status() → Status

Returns a status code indicating the first error that was met by QSettings, or NoError if no error occurred.

Be aware that QSettings delays performing some operations. For this reason, you might want to call sync() to ensure that the data stored in QSettings is written to disk before calling .

See also

sync().

sync()

Writes any unsaved changes to permanent storage, and reloads any settings that have been changed in the meantime by another application.

This function is called automatically from QSettings’s destructor and by the event loop at regular intervals, so you normally don’t need to call it yourself.

See also

status().

value(str, defaultValue: Any = None, type: type = None) → object: TODO