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Internal/Contributor docs for the Qt SDK. Note: These are NOT official API docs; those are found at https://doc.qt.io/
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Public Types | Signals | Public Member Functions | Protected Member Functions | List of all members
QValidator Class Referenceabstract

The QValidator class provides validation of input text. More...

#include <qvalidator.h>

+ Inheritance diagram for QValidator:
+ Collaboration diagram for QValidator:

Public Types

enum  State { Invalid , Intermediate , Acceptable }
 This enum type defines the states in which a validated string can exist. More...
 

Signals

void changed ()
 This signal is emitted when any property that may affect the validity of a string has changed.
 
- Signals inherited from QObject
void destroyed (QObject *=nullptr)
 This signal is emitted immediately before the object obj is destroyed, after any instances of QPointer have been notified, and cannot be blocked.
 
void objectNameChanged (const QString &objectName, QPrivateSignal)
 This signal is emitted after the object's name has been changed.
 

Public Member Functions

 QValidator (QObject *parent=nullptr)
 Sets up the validator.
 
 ~QValidator ()
 Destroys the validator, freeing any storage and other resources used.
 
void setLocale (const QLocale &locale)
 Sets the locale that will be used for the validator.
 
QLocale locale () const
 Returns the locale for the validator.
 
virtual State validate (QString &, int &) const =0
 This virtual function returns \l Invalid if input is invalid according to this validator's rules, \l Intermediate if it is likely that a little more editing will make the input acceptable (e.g.
 
virtual void fixup (QString &) const
 This function attempts to change input to be valid according to this validator's rules.
 
- Public Member Functions inherited from QObject
Q_INVOKABLE QObject (QObject *parent=nullptr)
 Constructs an object with parent object parent.
 
virtual ~QObject ()
 Destroys the object, deleting all its child objects.
 
virtual bool event (QEvent *event)
 This virtual function receives events to an object and should return true if the event e was recognized and processed.
 
virtual bool eventFilter (QObject *watched, QEvent *event)
 Filters events if this object has been installed as an event filter for the watched object.
 
QString objectName () const
 
Q_WEAK_OVERLOAD void setObjectName (const QString &name)
 Sets the object's name to name.
 
void setObjectName (QAnyStringView name)
 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
 
QBindable< QString > bindableObjectName ()
 
bool isWidgetType () const
 Returns true if the object is a widget; otherwise returns false.
 
bool isWindowType () const
 Returns true if the object is a window; otherwise returns false.
 
bool isQuickItemType () const
 Returns true if the object is a QQuickItem; otherwise returns false.
 
bool signalsBlocked () const noexcept
 Returns true if signals are blocked; otherwise returns false.
 
bool blockSignals (bool b) noexcept
 If block is true, signals emitted by this object are blocked (i.e., emitting a signal will not invoke anything connected to it).
 
QThread * thread () const
 Returns the thread in which the object lives.
 
bool moveToThread (QThread *thread QT6_DECL_NEW_OVERLOAD_TAIL)
 Changes the thread affinity for this object and its children and returns true on success.
 
int startTimer (int interval, Qt::TimerType timerType=Qt::CoarseTimer)
 This is an overloaded function that will start a timer of type timerType and a timeout of interval milliseconds.
 
int startTimer (std::chrono::nanoseconds time, Qt::TimerType timerType=Qt::CoarseTimer)
 
void killTimer (int id)
 Kills the timer with timer identifier, id.
 
void killTimer (Qt::TimerId id)
 
template<typename T >
T findChild (QAnyStringView aName, Qt::FindChildOptions options=Qt::FindChildrenRecursively) const
 Returns the child of this object that can be cast into type T and that is called name, or \nullptr if there is no such object.
 
template<typename T >
QList< T > findChildren (QAnyStringView aName, Qt::FindChildOptions options=Qt::FindChildrenRecursively) const
 Returns all children of this object with the given name that can be cast to type T, or an empty list if there are no such objects.
 
template<typename T >
T findChild (Qt::FindChildOptions options=Qt::FindChildrenRecursively) const
 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
 
template<typename T >
QList< T > findChildren (Qt::FindChildOptions options=Qt::FindChildrenRecursively) const
 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
 
const QObjectList & children () const
 Returns a list of child objects.
 
void setParent (QObject *parent)
 Makes the object a child of parent.
 
void installEventFilter (QObject *filterObj)
 Installs an event filter filterObj on this object.
 
void removeEventFilter (QObject *obj)
 Removes an event filter object obj from this object.
 
QMetaObject::Connection connect (const QObject *sender, const char *signal, const char *member, Qt::ConnectionType type=Qt::AutoConnection) const
 
bool disconnect (const char *signal=nullptr, const QObject *receiver=nullptr, const char *member=nullptr) const
 
bool disconnect (const QObject *receiver, const char *member=nullptr) const
 
void dumpObjectTree () const
 Dumps a tree of children to the debug output.
 
void dumpObjectInfo () const
 Dumps information about signal connections, etc.
 
bool setProperty (const char *name, const QVariant &value)
 Sets the value of the object's name property to value.
 
bool setProperty (const char *name, QVariant &&value)
 
QVariant property (const char *name) const
 Returns the value of the object's name property.
 
QList< QByteArray > dynamicPropertyNames () const
 
QBindingStorage * bindingStorage ()
 
const QBindingStorage * bindingStorage () const
 
QObject * parent () const
 Returns a pointer to the parent object.
 
bool inherits (const char *classname) const
 Returns true if this object is an instance of a class that inherits className or a QObject subclass that inherits className; otherwise returns false.
 

Protected Member Functions

 QValidator (QObjectPrivate &d, QObject *parent)
 
 QValidator (QValidatorPrivate &d, QObject *parent)
 
- Protected Member Functions inherited from QObject
QObject * sender () const
 Returns a pointer to the object that sent the signal, if called in a slot activated by a signal; otherwise it returns \nullptr.
 
int senderSignalIndex () const
 
int receivers (const char *signal) const
 Returns the number of receivers connected to the signal.
 
bool isSignalConnected (const QMetaMethod &signal) const
 
virtual void timerEvent (QTimerEvent *event)
 This event handler can be reimplemented in a subclass to receive timer events for the object.
 
virtual void childEvent (QChildEvent *event)
 This event handler can be reimplemented in a subclass to receive child events.
 
virtual void customEvent (QEvent *event)
 This event handler can be reimplemented in a subclass to receive custom events.
 
virtual void connectNotify (const QMetaMethod &signal)
 
virtual void disconnectNotify (const QMetaMethod &signal)
 
 QObject (QObjectPrivate &dd, QObject *parent=nullptr)
 

Additional Inherited Members

- Public Slots inherited from QObject
void deleteLater ()
 \threadsafe
 
- Static Public Member Functions inherited from QObject
static QMetaObject::Connection connect (const QObject *sender, const char *signal, const QObject *receiver, const char *member, Qt::ConnectionType=Qt::AutoConnection)
 \threadsafe
 
static QMetaObject::Connection connect (const QObject *sender, const QMetaMethod &signal, const QObject *receiver, const QMetaMethod &method, Qt::ConnectionType type=Qt::AutoConnection)
 
template<typename Func1 , typename Func2 >
static QMetaObject::Connection connect (const typename QtPrivate::FunctionPointer< Func1 >::Object *sender, Func1 signal, const typename QtPrivate::ContextTypeForFunctor< Func2 >::ContextType *context, Func2 &&slot, Qt::ConnectionType type=Qt::AutoConnection)
 
template<typename Func1 , typename Func2 >
static QMetaObject::Connection connect (const typename QtPrivate::FunctionPointer< Func1 >::Object *sender, Func1 signal, Func2 &&slot)
 
static bool disconnect (const QObject *sender, const char *signal, const QObject *receiver, const char *member)
 \threadsafe
 
static bool disconnect (const QObject *sender, const QMetaMethod &signal, const QObject *receiver, const QMetaMethod &member)
 
static bool disconnect (const QMetaObject::Connection &)
 Disconnect a connection.
 
template<typename Func1 , typename Func2 >
static bool disconnect (const typename QtPrivate::FunctionPointer< Func1 >::Object *sender, Func1 signal, const typename QtPrivate::FunctionPointer< Func2 >::Object *receiver, Func2 slot)
 
template<typename Func1 >
static bool disconnect (const typename QtPrivate::FunctionPointer< Func1 >::Object *sender, Func1 signal, const QObject *receiver, void **zero)
 
- Protected Attributes inherited from QObject
QScopedPointer< QObjectData > d_ptr
 
- Properties inherited from QObject
QString objectName
 the name of this object
 
- Related Symbols inherited from QObject
 Returns the given object cast to type T if the object is of type T (or of a subclass); otherwise returns \nullptr.
 
 
 
 \macro Q_CLASSINFO(Name, Value)
 

Detailed Description

The QValidator class provides validation of input text.

\inmodule QtGui

The class itself is abstract. Two subclasses, \l QIntValidator and \l QDoubleValidator, provide basic numeric-range checking, and \l QRegularExpressionValidator provides general checking using a custom regular expression.

If the built-in validators aren't sufficient, you can subclass QValidator. The class has two virtual functions: validate() and fixup().

\l validate() must be implemented by every subclass. It returns \l Invalid, \l Intermediate or \l Acceptable depending on whether its argument is valid (for the subclass's definition of valid).

These three states require some explanation. An \l Invalid string is clearly invalid. \l Intermediate is less obvious: the concept of validity is difficult to apply when the string is incomplete (still being edited). QValidator defines \l Intermediate as the property of a string that is neither clearly invalid nor acceptable as a final result. \l Acceptable means that the string is acceptable as a final result. One might say that any string that is a plausible intermediate state during entry of an \l Acceptable string is \l Intermediate.

Here are some examples:

\list

  • For a line edit that accepts integers from 10 to 1000 inclusive, 42 and 123 are \l Acceptable, the empty string, 5, or 1234 are \l Intermediate, and "asdf" and 10114 is \l Invalid.
  • For an editable combobox that accepts URLs, any well-formed URL is \l Acceptable, "http://example.com/," is \l Intermediate (it might be a cut and paste action that accidentally took in a comma at the end), the empty string is \l Intermediate (the user might select and delete all of the text in preparation for entering a new URL) and "http:///./" is \l Invalid.
  • For a spin box that accepts lengths, "11cm" and "1in" are \l Acceptable, "11" and the empty string are \l Intermediate, and "http://example.com" and "hour" are \l Invalid.

\endlist

\l fixup() is provided for validators that can repair some user errors. The default implementation does nothing. QLineEdit, for example, will call fixup() if the user presses Enter (or Return) and the content is not currently valid. This allows the fixup() function the opportunity of performing some magic to make an \l Invalid string \l Acceptable.

A validator has a locale, set with setLocale(). It is typically used to parse localized data. For example, QIntValidator and QDoubleValidator use it to parse localized representations of integers and doubles.

QValidator is typically used with QLineEdit, QSpinBox and QComboBox.

See also
QIntValidator, QDoubleValidator, QRegularExpressionValidator, {Line Edits Example}

Definition at line 23 of file qvalidator.h.

Member Enumeration Documentation

◆ State

enum QValidator::State

This enum type defines the states in which a validated string can exist.

\value Invalid The string is clearly invalid. \value Intermediate The string is a plausible intermediate value. \value Acceptable The string is acceptable as a final result; i.e. it is valid.

Enumerator
Invalid 
Intermediate 
Acceptable 

Definition at line 30 of file qvalidator.h.

Constructor & Destructor Documentation

◆ QValidator() [1/3]

QValidator::QValidator ( QObject * parent = nullptr)
explicit

Sets up the validator.

The parent parameter is passed on to the QObject constructor.

Definition at line 175 of file qvalidator.cpp.

◆ ~QValidator()

QValidator::~QValidator ( )

Destroys the validator, freeing any storage and other resources used.

Definition at line 185 of file qvalidator.cpp.

◆ QValidator() [2/3]

QValidator::QValidator ( QObjectPrivate & d,
QObject * parent )
protected

Definition at line 495 of file qvalidator.cpp.

◆ QValidator() [3/3]

QValidator::QValidator ( QValidatorPrivate & d,
QObject * parent )
protected

Definition at line 503 of file qvalidator.cpp.

Member Function Documentation

◆ changed

void QValidator::changed ( )
signal

This signal is emitted when any property that may affect the validity of a string has changed.

◆ fixup()

void QValidator::fixup ( QString & input) const
virtual

This function attempts to change input to be valid according to this validator's rules.

It need not result in a valid string: callers of this function must re-test afterwards; the default does nothing.

Reimplementations of this function can change input even if they do not produce a valid string. For example, an ISBN validator might want to delete every character except digits and "-", even if the result is still not a valid ISBN; a surname validator might want to remove whitespace from the start and end of the string, even if the resulting string is not in the list of accepted surnames.

Reimplemented in QDoubleValidator, QIntValidator, and QSpinBoxValidator.

Definition at line 250 of file qvalidator.cpp.

◆ locale()

QLocale QValidator::locale ( ) const

Returns the locale for the validator.

The locale is by default initialized to the same as QLocale().

See also
setLocale()
QLocale::QLocale()

Definition at line 195 of file qvalidator.cpp.

◆ setLocale()

void QValidator::setLocale ( const QLocale & locale)

Sets the locale that will be used for the validator.

Unless setLocale has been called, the validator will use the default locale set with QLocale::setDefault(). If a default locale has not been set, it is the operating system's locale.

See also
locale(), QLocale::setDefault()

Definition at line 209 of file qvalidator.cpp.

◆ validate()

virtual State QValidator::validate ( QString & input,
int & pos ) const
pure virtual

This virtual function returns \l Invalid if input is invalid according to this validator's rules, \l Intermediate if it is likely that a little more editing will make the input acceptable (e.g.

the user types "4" into a widget which accepts integers between 10 and 99), and \l Acceptable if the input is valid.

The function can change both input and pos (the cursor position) if required.

Implemented in qdesigner_internal::BlankSuppressingValidator, qdesigner_internal::BlankSuppressingValidator, qdesigner_internal::QLongLongValidator, qdesigner_internal::QULongLongValidator, QDoubleValidator, QIntValidator, and QSpinBoxValidator.

The documentation for this class was generated from the following files: