QMessageBox

The QMessageBox class provides a modal dialog for informing the user or for asking the user a question and receiving an answer. More

Inheritance diagram of PySide2.QtWidgets.QMessageBox

Synopsis

Functions

Signals

Static functions

  • def about (parent, title, text)

  • def aboutQt (parent[, title=”“])

  • def critical (parent, title, text, button0, button1)

  • def critical (parent, title, text[, buttons=QMessageBox.Ok[, defaultButton=NoButton]])

  • def information (parent, title, text, button0[, button1=NoButton])

  • def information (parent, title, text[, buttons=QMessageBox.Ok[, defaultButton=NoButton]])

  • def question (parent, title, text, button0, button1)

  • def question (parent, title, text[, buttons=QMessageBox.StandardButtons(Yes | No)[, defaultButton=NoButton]])

  • def standardIcon (icon)

  • def warning (parent, title, text, button0, button1)

  • def warning (parent, title, text[, buttons=QMessageBox.Ok[, defaultButton=NoButton]])

Detailed Description

A message box displays a primary text to alert the user to a situation, an informative text to further explain the alert or to ask the user a question, and an optional detailed text to provide even more data if the user requests it. A message box can also display an icon and standard buttons for accepting a user response.

Two APIs for using QMessageBox are provided, the property-based API, and the static functions. Calling one of the static functions is the simpler approach, but it is less flexible than using the property-based API, and the result is less informative. Using the property-based API is recommended.

The Property-based API

To use the property-based API, construct an instance of QMessageBox , set the desired properties, and call exec() to show the message. The simplest configuration is to set only the message text property.

QMessageBox msgBox;
msgBox.setText("The document has been modified.");
msgBox.exec();

The user must click the OK button to dismiss the message box. The rest of the GUI is blocked until the message box is dismissed.

../../_images/msgbox1.png

A better approach than just alerting the user to an event is to also ask the user what to do about it. Store the question in the informative text property, and set the standard buttons property to the set of buttons you want as the set of user responses. The buttons are specified by combining values from StandardButtons using the bitwise OR operator. The display order for the buttons is platform-dependent. For example, on Windows, Save is displayed to the left of Cancel, whereas on Mac OS, the order is reversed.

Mark one of your standard buttons to be your default button .

QMessageBox msgBox;
msgBox.setText("The document has been modified.");
msgBox.setInformativeText("Do you want to save your changes?");
msgBox.setStandardButtons(QMessageBox::Save | QMessageBox::Discard | QMessageBox::Cancel);
msgBox.setDefaultButton(QMessageBox::Save);
int ret = msgBox.exec();

This is the approach recommended in the macOS Guidelines. Similar guidelines apply for the other platforms, but note the different ways the informative text is handled for different platforms.

../../_images/msgbox2.png

The exec() slot returns the StandardButtons value of the button that was clicked.

switch (ret) {
  case QMessageBox::Save:
      // Save was clicked
      break;
  case QMessageBox::Discard:
      // Don't Save was clicked
      break;
  case QMessageBox::Cancel:
      // Cancel was clicked
      break;
  default:
      // should never be reached
      break;
}

To give the user more information to help him answer the question, set the detailed text property. If the detailed text property is set, the Show Details… button will be shown.

../../_images/msgbox3.png

Clicking the Show Details… button displays the detailed text.

../../_images/msgbox4.png

Rich Text and the Text Format Property

The detailed text property is always interpreted as plain text. The main text and informative text properties can be either plain text or rich text. These strings are interpreted according to the setting of the text format property. The default setting is auto-text .

Note that for some plain text strings containing XML meta-characters, the auto-text rich text detection test may fail causing your plain text string to be interpreted incorrectly as rich text. In these rare cases, use convertFromPlainText() to convert your plain text string to a visually equivalent rich text string, or set the text format property explicitly with setTextFormat() .

Severity Levels and the Icon and Pixmap Properties

QMessageBox supports four predefined message severity levels, or message types, which really only differ in the predefined icon they each show. Specify one of the four predefined message types by setting the icon property to one of the predefined icons . The following rules are guidelines:

../../_images/qmessagebox-quest.png

Question

For asking a question during normal operations.

../../_images/qmessagebox-info.png

Information

For reporting information about normal operations.

../../_images/qmessagebox-warn.png

Warning

For reporting non-critical errors.

../../_images/qmessagebox-crit.png

Critical

For reporting critical errors.

Predefined icons are not defined by QMessageBox , but provided by the style. The default value is No Icon . The message boxes are otherwise the same for all cases. When using a standard icon, use the one recommended in the table, or use the one recommended by the style guidelines for your platform. If none of the standard icons is right for your message box, you can use a custom icon by setting the icon pixmap property instead of setting the icon property.

In summary, to set an icon, use either setIcon() for one of the standard icons, or setIconPixmap() for a custom icon.

The Static Functions API

Building message boxes with the static functions API, although convenient, is less flexible than using the property-based API, because the static function signatures lack parameters for setting the informative text and detailed text properties. One work-around for this has been to use the title parameter as the message box main text and the text parameter as the message box informative text. Because this has the obvious drawback of making a less readable message box, platform guidelines do not recommend it. The Microsoft Windows User Interface Guidelines recommend using the application name as the window's title , which means that if you have an informative text in addition to your main text, you must concatenate it to the text parameter.

Note that the static function signatures have changed with respect to their button parameters, which are now used to set the standard buttons and the default button .

Static functions are available for creating information() , question() , warning() , and critical() message boxes.

int ret = QMessageBox::warning(this, tr("My Application"),
                               tr("The document has been modified.\n"
                                  "Do you want to save your changes?"),
                               QMessageBox::Save | QMessageBox::Discard
                               | QMessageBox::Cancel,
                               QMessageBox::Save);

The Standard Dialogs example shows how to use QMessageBox and the other built-in Qt dialogs.

Advanced Usage

If the standard buttons are not flexible enough for your message box, you can use the addButton() overload that takes a text and a ButtonRole to add custom buttons. The ButtonRole is used by QMessageBox to determine the ordering of the buttons on screen (which varies according to the platform). You can test the value of clickedButton() after calling exec() . For example,

QMessageBox msgBox;
QPushButton *connectButton = msgBox.addButton(tr("Connect"), QMessageBox::ActionRole);
QPushButton *abortButton = msgBox.addButton(QMessageBox::Abort);

msgBox.exec();

if (msgBox.clickedButton() == connectButton) {
    // connect
} else if (msgBox.clickedButton() == abortButton) {
    // abort
}

Default and Escape Keys

The default button (i.e., the button activated when Enter is pressed) can be specified using setDefaultButton() . If a default button is not specified, QMessageBox tries to find one based on the button roles of the buttons used in the message box.

The escape button (the button activated when Esc is pressed) can be specified using setEscapeButton() . If an escape button is not specified, QMessageBox tries to find one using these rules:

  1. If there is only one button, it is the button activated when Esc is pressed.

  2. If there is a Cancel button, it is the button activated when Esc is pressed.

  3. If there is exactly one button having either the Reject role or the the No role , it is the button activated when Esc is pressed.

When an escape button can’t be determined using these rules, pressing Esc has no effect.

See also

QDialogButtonBox GUI Design Handbook: Message Box Standard Dialogs Example Application Example

class QMessageBox(icon, title, text[, buttons=QMessageBox.NoButton[, parent=None[, flags=Qt.Dialog | Qt.MSWindowsFixedSizeDialogHint]]])

QMessageBox([parent=None])

param parent

QWidget

param title

unicode

param buttons

StandardButtons

param flags

WindowFlags

param icon

Icon

param text

unicode

Constructs a message box with the given icon , title , text , and standard buttons . Standard or custom buttons can be added at any time using addButton() . The parent and f arguments are passed to the QDialog constructor.

The message box is an application modal dialog box.

On macOS , if parent is not None and you want your message box to appear as a Sheet of that parent, set the message box’s window modality to WindowModal (default). Otherwise, the message box will be a standard dialog.

See also

setWindowTitle() setText() setIcon() setStandardButtons()

Constructs a message box with no text and no buttons. parent is passed to the QDialog constructor.

On macOS , if you want your message box to appear as a Sheet of its parent , set the message box’s window modality to WindowModal or use open() . Otherwise, the message box will be a standard dialog.

PySide2.QtWidgets.QMessageBox.Icon

This enum has the following values:

Constant

Description

QMessageBox.NoIcon

the message box does not have any icon.

QMessageBox.Question

an icon indicating that the message is asking a question.

QMessageBox.Information

an icon indicating that the message is nothing out of the ordinary.

QMessageBox.Warning

an icon indicating that the message is a warning, but can be dealt with.

QMessageBox.Critical

an icon indicating that the message represents a critical problem.

PySide2.QtWidgets.QMessageBox.ButtonRole
PySide2.QtWidgets.QMessageBox.StandardButton

These enums describe flags for standard buttons. Each button has a defined ButtonRole .

Constant

Description

QMessageBox.Ok

An “OK” button defined with the AcceptRole .

QMessageBox.Open

An “Open” button defined with the AcceptRole .

QMessageBox.Save

A “Save” button defined with the AcceptRole .

QMessageBox.Cancel

A “Cancel” button defined with the RejectRole .

QMessageBox.Close

A “Close” button defined with the RejectRole .

QMessageBox.Discard

A “Discard” or “Don’t Save” button, depending on the platform, defined with the DestructiveRole .

QMessageBox.Apply

An “Apply” button defined with the ApplyRole .

QMessageBox.Reset

A “Reset” button defined with the ResetRole .

QMessageBox.RestoreDefaults

A “Restore Defaults” button defined with the ResetRole .

QMessageBox.Help

A “Help” button defined with the HelpRole .

QMessageBox.SaveAll

A “Save All” button defined with the AcceptRole .

QMessageBox.Yes

A “Yes” button defined with the YesRole .

QMessageBox.YesToAll

A “Yes to All” button defined with the YesRole .

QMessageBox.No

A “No” button defined with the NoRole .

QMessageBox.NoToAll

A “No to All” button defined with the NoRole .

QMessageBox.Abort

An “Abort” button defined with the RejectRole .

QMessageBox.Retry

A “Retry” button defined with the AcceptRole .

QMessageBox.Ignore

An “Ignore” button defined with the AcceptRole .

QMessageBox.NoButton

An invalid button.

The following values are obsolete:

Constant

Description

QMessageBox.YesAll

Use instead.

QMessageBox.NoAll

Use instead.

QMessageBox.Default

Use the defaultButton argument of information() , warning() , etc. instead, or call setDefaultButton() .

QMessageBox.Escape

Call setEscapeButton() instead.

QMessageBox.FlagMask

QMessageBox.ButtonMask

See also

ButtonRole standardButtons

static PySide2.QtWidgets.QMessageBox.about(parent, title, text)
Parameters
  • parentQWidget

  • title – unicode

  • text – unicode

Displays a simple about box with title title and text text . The about box’s parent is parent .

looks for a suitable icon in four locations:

  1. It prefers parent->icon() if that exists.

  2. If not, it tries the top-level widget containing parent.

  3. If that fails, it tries the PySide2.QtWidgets.QApplication.activeWindow()

  4. As a last resort it uses the Information icon.

The about box has a single button labelled “OK”. On macOS , the about box is popped up as a modeless window; on other platforms, it is currently application modal.

static PySide2.QtWidgets.QMessageBox.aboutQt(parent[, title=""])
Parameters
  • parentQWidget

  • title – unicode

Displays a simple message box about Qt, with the given title and centered over parent (if parent is not None ). The message includes the version number of Qt being used by the application.

This is useful for inclusion in the Help menu of an application, as shown in the Menus example.

QApplication provides this functionality as a slot.

On macOS , the about box is popped up as a modeless window; on other platforms, it is currently application modal.

See also

aboutQt()

PySide2.QtWidgets.QMessageBox.addButton(button, role)
Parameters

Adds the given button to the message box with the specified role .

PySide2.QtWidgets.QMessageBox.addButton(button)
Parameters

buttonStandardButton

Return type

QPushButton

This is an overloaded function.

Adds a standard button to the message box if it is valid to do so, and returns the push button.

PySide2.QtWidgets.QMessageBox.addButton(text, role)
Parameters
Return type

QPushButton

PySide2.QtWidgets.QMessageBox.button(which)
Parameters

whichStandardButton

Return type

QAbstractButton

Returns a pointer corresponding to the standard button which , or None if the standard button doesn’t exist in this message box.

PySide2.QtWidgets.QMessageBox.buttonClicked(button)
Parameters

buttonQAbstractButton

PySide2.QtWidgets.QMessageBox.buttonRole(button)
Parameters

buttonQAbstractButton

Return type

ButtonRole

Returns the button role for the specified button . This function returns InvalidRole if button is None or has not been added to the message box.

PySide2.QtWidgets.QMessageBox.buttonText(button)
Parameters

buttonint

Return type

unicode

Returns the text of the message box button button , or an empty string if the message box does not contain the button.

Use button() and text() instead.

See also

setButtonText()

PySide2.QtWidgets.QMessageBox.buttons()
Return type

Returns a list of all the buttons that have been added to the message box.

PySide2.QtWidgets.QMessageBox.checkBox()
Return type

QCheckBox

Returns the checkbox shown on the dialog. This is None if no checkbox is set.

See also

setCheckBox()

PySide2.QtWidgets.QMessageBox.clickedButton()
Return type

QAbstractButton

Returns the button that was clicked by the user, or None if the user hit the Esc key and no escape button was set.

If exec() hasn’t been called yet, returns nullptr.

Example:

QMessageBox messageBox(this);
QAbstractButton *disconnectButton =
      messageBox.addButton(tr("Disconnect"), QMessageBox::ActionRole);
...
messageBox.exec();
if (messageBox.clickedButton() == disconnectButton) {
    ...
}
static PySide2.QtWidgets.QMessageBox.critical(parent, title, text, button0, button1)
Parameters
Return type

int

static PySide2.QtWidgets.QMessageBox.critical(parent, title, text[, buttons=QMessageBox.Ok[, defaultButton=NoButton]])
Parameters
  • parentQWidget

  • title – unicode

  • text – unicode

  • buttonsStandardButtons

  • defaultButtonStandardButton

Return type

StandardButton

PySide2.QtWidgets.QMessageBox.defaultButton()
Return type

QPushButton

Returns the button that should be the message box’s default button . Returns nullptr if no default button was set.

PySide2.QtWidgets.QMessageBox.detailedText()
Return type

unicode

PySide2.QtWidgets.QMessageBox.escapeButton()
Return type

QAbstractButton

Returns the button that is activated when escape is pressed.

By default, QMessageBox attempts to automatically detect an escape button as follows:

  1. If there is only one button, it is made the escape button.

  2. If there is a Cancel button, it is made the escape button.

  3. On macOS only, if there is exactly one button with the role RejectRole , it is made the escape button.

When an escape button could not be automatically detected, pressing Esc has no effect.

PySide2.QtWidgets.QMessageBox.icon()
Return type

Icon

See also

setIcon()

PySide2.QtWidgets.QMessageBox.iconPixmap()
Return type

QPixmap

See also

setIconPixmap()

static PySide2.QtWidgets.QMessageBox.information(parent, title, text[, buttons=QMessageBox.Ok[, defaultButton=NoButton]])
Parameters
  • parentQWidget

  • title – unicode

  • text – unicode

  • buttonsStandardButtons

  • defaultButtonStandardButton

Return type

StandardButton

static PySide2.QtWidgets.QMessageBox.information(parent, title, text, button0[, button1=NoButton])
Parameters
Return type

StandardButton

PySide2.QtWidgets.QMessageBox.informativeText()
Return type

unicode

PySide2.QtWidgets.QMessageBox.open(receiver, member)
Parameters
  • receiverQObject

  • member – str

Opens the dialog and connects its finished() or buttonClicked() signal to the slot specified by receiver and member . If the slot in member has a pointer for its first parameter the connection is to buttonClicked() , otherwise the connection is to finished() .

The signal will be disconnected from the slot when the dialog is closed.

static PySide2.QtWidgets.QMessageBox.question(parent, title, text[, buttons=QMessageBox.StandardButtons(Yes | No)[, defaultButton=NoButton]])
Parameters
  • parentQWidget

  • title – unicode

  • text – unicode

  • buttonsStandardButtons

  • defaultButtonStandardButton

Return type

StandardButton

static PySide2.QtWidgets.QMessageBox.question(parent, title, text, button0, button1)
Parameters
Return type

int

PySide2.QtWidgets.QMessageBox.removeButton(button)
Parameters

buttonQAbstractButton

Removes button from the button box without deleting it.

PySide2.QtWidgets.QMessageBox.setButtonText(button, text)
Parameters
  • buttonint

  • text – unicode

Sets the text of the message box button button to text . Setting the text of a button that is not in the message box is silently ignored.

Use addButton() instead.

See also

buttonText()

PySide2.QtWidgets.QMessageBox.setCheckBox(cb)
Parameters

cbQCheckBox

Sets the checkbox cb on the message dialog. The message box takes ownership of the checkbox. The argument cb can be None to remove an existing checkbox from the message box.

See also

checkBox()

PySide2.QtWidgets.QMessageBox.setDefaultButton(button)
Parameters

buttonStandardButton

Sets the message box’s default button to button .

PySide2.QtWidgets.QMessageBox.setDefaultButton(button)
Parameters

buttonQPushButton

Sets the message box’s default button to button .

PySide2.QtWidgets.QMessageBox.setDetailedText(text)
Parameters

text – unicode

See also

detailedText()

PySide2.QtWidgets.QMessageBox.setEscapeButton(button)
Parameters

buttonQAbstractButton

Sets the button that gets activated when the Escape key is pressed to button .

PySide2.QtWidgets.QMessageBox.setEscapeButton(button)
Parameters

buttonStandardButton

Sets the buttons that gets activated when the Escape key is pressed to button .

PySide2.QtWidgets.QMessageBox.setIcon(arg__1)
Parameters

arg__1Icon

See also

icon()

PySide2.QtWidgets.QMessageBox.setIconPixmap(pixmap)
Parameters

pixmapQPixmap

See also

iconPixmap()

PySide2.QtWidgets.QMessageBox.setInformativeText(text)
Parameters

text – unicode

PySide2.QtWidgets.QMessageBox.setStandardButtons(buttons)
Parameters

buttonsStandardButtons

PySide2.QtWidgets.QMessageBox.setText(text)
Parameters

text – unicode

See also

text()

PySide2.QtWidgets.QMessageBox.setTextFormat(format)
Parameters

formatTextFormat

See also

textFormat()

PySide2.QtWidgets.QMessageBox.setTextInteractionFlags(flags)
Parameters

flagsTextInteractionFlags

PySide2.QtWidgets.QMessageBox.standardButton(button)
Parameters

buttonQAbstractButton

Return type

StandardButton

Returns the standard button enum value corresponding to the given button , or NoButton if the given button isn’t a standard button.

PySide2.QtWidgets.QMessageBox.standardButtons()
Return type

StandardButtons

static PySide2.QtWidgets.QMessageBox.standardIcon(icon)
Parameters

iconIcon

Return type

QPixmap

Returns the pixmap used for a standard icon. This allows the pixmaps to be used in more complex message boxes. icon specifies the required icon, e.g. Question , Information , Warning or Critical .

Call standardIcon() with SP_MessageBoxInformation etc. instead.

PySide2.QtWidgets.QMessageBox.text()
Return type

unicode

See also

setText()

PySide2.QtWidgets.QMessageBox.textFormat()
Return type

TextFormat

See also

setTextFormat()

PySide2.QtWidgets.QMessageBox.textInteractionFlags()
Return type

TextInteractionFlags

static PySide2.QtWidgets.QMessageBox.warning(parent, title, text[, buttons=QMessageBox.Ok[, defaultButton=NoButton]])
Parameters
  • parentQWidget

  • title – unicode

  • text – unicode

  • buttonsStandardButtons

  • defaultButtonStandardButton

Return type

StandardButton

static PySide2.QtWidgets.QMessageBox.warning(parent, title, text, button0, button1)
Parameters
Return type

int