The QJsonValue class encapsulates a value in JSON. More...

#include <qjsonvalue.h>

Public Types
enum	Type { Null = 0x0 , Bool = 0x1 , Double = 0x2 , String = 0x3 , Array = 0x4 , Object = 0x5 , Undefined = 0x80 }

Public Member Functions
	QJsonValue (Type=Null)

	QJsonValue (bool b)

	QJsonValue (double n)

	QJsonValue (int n)

	QJsonValue (qint64 v)

	QJsonValue (const QString &s)

	QJsonValue (QLatin1String s)

QT_ASCII_CAST_WARN	QJsonValue (const char *s)

	QJsonValue (const QJsonArray &a)

	QJsonValue (QJsonArray &&a) noexcept

	QJsonValue (const QJsonObject &o)

	QJsonValue (QJsonObject &&o) noexcept

	~QJsonValue ()

	QJsonValue (const QJsonValue &other)

QJsonValue &	operator= (const QJsonValue &other)

	QJsonValue (QJsonValue &&other) noexcept

QJsonValue &	operator= (QJsonValue &&other) noexcept

void	swap (QJsonValue &other) noexcept

QVariant	toVariant () const

Type	type () const

bool	isNull () const

bool	isBool () const

bool	isDouble () const

bool	isString () const

bool	isArray () const

bool	isObject () const

bool	isUndefined () const

bool	toBool (bool defaultValue=false) const

int	toInt (int defaultValue=0) const

qint64	toInteger (qint64 defaultValue=0) const

double	toDouble (double defaultValue=0) const

QString	toString () const

QString	toString (const QString &defaultValue) const

QJsonArray	toArray () const

QJsonArray	toArray (const QJsonArray &defaultValue) const

QJsonObject	toObject () const

QJsonObject	toObject (const QJsonObject &defaultValue) const

const QJsonValue	operator[] (const QString &key) const

const QJsonValue	operator[] (QStringView key) const

const QJsonValue	operator[] (QLatin1String key) const

const QJsonValue	operator[] (qsizetype i) const

bool	operator== (const QJsonValue &other) const

bool	operator!= (const QJsonValue &other) const

Static Public Member Functions
static QJsonValue	fromVariant (const QVariant &variant)

Friends
class	QJsonPrivate::Value

class	QJsonArray

class	QJsonObject

class	QCborValue

Q_CORE_EXPORT QDebug	operator<< (QDebug, const QJsonValue &)

Q_CORE_EXPORT QDataStream &	operator<< (QDataStream &, const QJsonValue &)

Detailed Description

The QJsonValue class encapsulates a value in JSON.

\inmodule QtCore

\reentrant

Since: 5.0

A value in JSON can be one of 6 basic types:

JSON is a format to store structured data. It has 6 basic data types:

\list

A value can represent any of the above data types. In addition, QJsonValue has one special flag to represent undefined values. This can be queried with isUndefined().

The type of the value can be queried with type() or accessors like isBool(), isString(), and so on. Likewise, the value can be converted to the type stored in it using the toBool(), toString() and so on.

Values are strictly typed internally and contrary to QVariant will not attempt to do any implicit type conversions. This implies that converting to a type that is not stored in the value will return a default constructed return value.

Definition at line 59 of file qjsonvalue.h.

Member Enumeration Documentation

◆ Type

enum QJsonValue::Type

This enum describes the type of the JSON value.

\value Null A Null value \value Bool A boolean value. Use toBool() to convert to a bool. \value Double A number value. Use toDouble() to convert to a double, or toInteger() to convert to a qint64. \value String A string. Use toString() to convert to a QString. \value Array An array. Use toArray() to convert to a QJsonArray. \value Object An object. Use toObject() to convert to a QJsonObject. \value Undefined The value is undefined. This is usually returned as an error condition, when trying to read an out of bounds value in an array or a non existent key in an object.

Enumerator
Null
Bool
Double
String
Array
Object
Undefined

Definition at line 62 of file qjsonvalue.h.

Constructor & Destructor Documentation

◆ QJsonValue() [1/14]

QJsonValue::QJsonValue ( Type type = Null )

Creates a QJsonValue of type type.

The default is to create a Null value.

Definition at line 116 of file qjsonvalue.cpp.

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◆ QJsonValue() [2/14]

QJsonValue::QJsonValue ( bool b )

Creates a value of type Bool, with value b.

Definition at line 145 of file qjsonvalue.cpp.

◆ QJsonValue() [3/14]

QJsonValue::QJsonValue ( double v )

Creates a value of type Double, with value v.

Definition at line 164 of file qjsonvalue.cpp.

◆ QJsonValue() [4/14]

QJsonValue::QJsonValue ( int v )

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. Creates a value of type Double, with value v.

Definition at line 173 of file qjsonvalue.cpp.

◆ QJsonValue() [5/14]

QJsonValue::QJsonValue ( qint64 v )

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. Creates a value of type Double, with value v. NOTE: the integer limits for IEEE 754 double precision data is 2^53 (-9007199254740992 to +9007199254740992). If you pass in values outside this range expect a loss of precision to occur.

Definition at line 184 of file qjsonvalue.cpp.

◆ QJsonValue() [6/14]

QJsonValue::QJsonValue ( const QString & s )

Creates a value of type String, with value s.

Definition at line 192 of file qjsonvalue.cpp.

◆ QJsonValue() [7/14]

QJsonValue::QJsonValue ( QLatin1String s )

Creates a value of type String, with value s.

Definition at line 212 of file qjsonvalue.cpp.

◆ QJsonValue() [8/14]

QJsonValue::QJsonValue ( const char * s )

inline

Creates a value of type String with value s, assuming UTF-8 encoding of the input.

You can disable this constructor by defining QT_NO_CAST_FROM_ASCII when you compile your applications.

Since: 5.3

Definition at line 80 of file qjsonvalue.h.

◆ QJsonValue() [9/14]

QJsonValue::QJsonValue ( const QJsonArray & a )

Creates a value of type Array, with value a.

Definition at line 220 of file qjsonvalue.cpp.

◆ QJsonValue() [10/14]

QJsonValue::QJsonValue ( QJsonArray && a )

noexcept

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Since: 6.3

Definition at line 229 of file qjsonvalue.cpp.

◆ QJsonValue() [11/14]

QJsonValue::QJsonValue ( const QJsonObject & o )

Creates a value of type Object, with value o.

Definition at line 237 of file qjsonvalue.cpp.

◆ QJsonValue() [12/14]

QJsonValue::QJsonValue ( QJsonObject && o )

noexcept

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Since: 6.3

Definition at line 246 of file qjsonvalue.cpp.

◆ ~QJsonValue()

QJsonValue::~QJsonValue ( )

default

Destroys the value.

◆ QJsonValue() [13/14]

QJsonValue::QJsonValue ( const QJsonValue & other )

Creates a copy of other.

Definition at line 260 of file qjsonvalue.cpp.

◆ QJsonValue() [14/14]

QJsonValue::QJsonValue ( QJsonValue && other )

noexcept

Since: 5.10

Move-constructs a QJsonValue from other.

Definition at line 275 of file qjsonvalue.cpp.

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Member Function Documentation

◆ fromVariant()

QJsonValue QJsonValue::fromVariant ( const QVariant & variant )

static

Converts variant to a QJsonValue and returns it.

The conversion will convert QVariant types as follows:

\table \header

Source type
Destination type \row
\list
QMetaType::Nullptr \endlist
QJsonValue::Null \row
\list
QMetaType::Bool \endlist
QJsonValue::Bool \row
\list
QMetaType::Int
QMetaType::UInt
QMetaType::LongLong
QMetaType::ULongLong
QMetaType::Float
QMetaType::Double \endlist
QJsonValue::Double \row
\list
QMetaType::QString \endlist
QJsonValue::String \row
\list
QMetaType::QStringList
QMetaType::QVariantList \endlist
QJsonValue::Array \row
\list
QMetaType::QVariantMap
QMetaType::QVariantHash \endlist
QJsonValue::Object

\row

\list
QMetaType::QUrl \endlist
QJsonValue::String. The conversion will use QUrl::toString() with flag QUrl::FullyEncoded, so as to ensure maximum compatibility in parsing the URL \row
\list
QMetaType::QUuid \endlist
QJsonValue::String. Since Qt 5.11, the resulting string will not include braces \row
\list
QMetaType::QCborValue \endlist
Whichever type QCborValue::toJsonValue() returns. \row
\list
QMetaType::QCborArray \endlist
QJsonValue::Array. See QCborValue::toJsonValue() for conversion restrictions. \row
\list
QMetaType::QCborMap \endlist
QJsonValue::Map. See QCborValue::toJsonValue() for conversion restrictions and the "stringification" of map keys. \endtable

Definition at line 482 of file qjsonvalue.cpp.

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◆ isArray()

bool QJsonValue::isArray ( ) const

inline

Returns true if the value contains an array.

See also: toArray()

Definition at line 111 of file qjsonvalue.h.

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◆ isBool()

bool QJsonValue::isBool ( ) const

inline

Returns true if the value contains a boolean.

See also: toBool()

Definition at line 108 of file qjsonvalue.h.

◆ isDouble()

bool QJsonValue::isDouble ( ) const

inline

Returns true if the value contains a double.

See also: toDouble()

Definition at line 109 of file qjsonvalue.h.

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◆ isNull()

bool QJsonValue::isNull ( ) const

inline

Returns true if the value is null.

Definition at line 107 of file qjsonvalue.h.

◆ isObject()

bool QJsonValue::isObject ( ) const

inline

Returns true if the value contains an object.

See also: toObject()

Definition at line 112 of file qjsonvalue.h.

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◆ isString()

bool QJsonValue::isString ( ) const

inline

Returns true if the value contains a string.

See also: toString()

Definition at line 110 of file qjsonvalue.h.

◆ isUndefined()

bool QJsonValue::isUndefined ( ) const

inline

Returns true if the value is undefined. This can happen in certain error cases as e.g. accessing a non existing key in a QJsonObject.

Definition at line 113 of file qjsonvalue.h.

◆ operator!=()

bool QJsonValue::operator!= ( const QJsonValue & other ) const

Returns true if the value is not equal to other.

Definition at line 888 of file qjsonvalue.cpp.

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◆ operator=() [1/2]

QJsonValue & QJsonValue::operator= ( const QJsonValue & other )

Assigns the value stored in other to this object.

Definition at line 268 of file qjsonvalue.cpp.

◆ operator=() [2/2]

QJsonValue & QJsonValue::operator= ( QJsonValue && other )

inlinenoexcept

Since: 5.10

Move-assigns other to this value.

Definition at line 95 of file qjsonvalue.h.

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◆ operator==()

bool QJsonValue::operator== ( const QJsonValue & other ) const

Returns true if the value is equal to other.

Definition at line 852 of file qjsonvalue.cpp.

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◆ operator[]() [1/4]

const QJsonValue QJsonValue::operator[] ( const QString & key ) const

Returns a QJsonValue representing the value for the key key.

Equivalent to calling toObject().value(key).

The returned QJsonValue is QJsonValue::Undefined if the key does not exist, or if isObject() is false.

Since: 5.10

See also: QJsonValue, QJsonValue::isUndefined(), QJsonObject

Definition at line 799 of file qjsonvalue.cpp.

◆ operator[]() [2/4]

const QJsonValue QJsonValue::operator[] ( QLatin1String key ) const

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Since: 5.10

Definition at line 821 of file qjsonvalue.cpp.

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◆ operator[]() [3/4]

const QJsonValue QJsonValue::operator[] ( qsizetype i ) const

Returns a QJsonValue representing the value for index i.

Equivalent to calling toArray().at(i).

The returned QJsonValue is QJsonValue::Undefined, if i is out of bounds, or if isArray() is false.

Since: 5.10

See also: QJsonValue, QJsonValue::isUndefined(), QJsonArray

Definition at line 841 of file qjsonvalue.cpp.

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◆ operator[]() [4/4]

const QJsonValue QJsonValue::operator[] ( QStringView key ) const

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Since: 5.14

Definition at line 809 of file qjsonvalue.cpp.

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◆ swap()

void QJsonValue::swap ( QJsonValue & other )

noexcept

Since: 5.10

Swaps the value other with this. This operation is very fast and never fails.

Definition at line 281 of file qjsonvalue.cpp.

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◆ toArray() [1/2]

QJsonArray QJsonValue::toArray ( ) const

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Converts the value to an array and returns it.

If type() is not Array, a \l{QJsonArray::}{QJsonArray()} will be returned.

Definition at line 754 of file qjsonvalue.cpp.

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◆ toArray() [2/2]

QJsonArray QJsonValue::toArray ( const QJsonArray & defaultValue ) const

Converts the value to an array and returns it.

If type() is not Array, the defaultValue will be returned.

Definition at line 737 of file qjsonvalue.cpp.

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◆ toBool()

bool QJsonValue::toBool ( bool defaultValue = false ) const

Converts the value to a bool and returns it.

If type() is not bool, the defaultValue will be returned.

Definition at line 636 of file qjsonvalue.cpp.

◆ toDouble()

double QJsonValue::toDouble ( double defaultValue = 0 ) const

Converts the value to a double and returns it.

If type() is not Double, the defaultValue will be returned.

Definition at line 705 of file qjsonvalue.cpp.

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◆ toInt()

int QJsonValue::toInt ( int defaultValue = 0 ) const

Since: 5.2 Converts the value to an int and returns it.

If type() is not Double or the value is not a whole number, the defaultValue will be returned.

Definition at line 655 of file qjsonvalue.cpp.

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◆ toInteger()

qint64 QJsonValue::toInteger ( qint64 defaultValue = 0 ) const

Since: 6.0 Converts the value to an integer and returns it.

If type() is not Double or the value is not a whole number representable as qint64, the defaultValue will be returned.

Definition at line 683 of file qjsonvalue.cpp.

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◆ toObject() [1/2]

QJsonObject QJsonValue::toObject ( ) const

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Converts the value to an object and returns it.

If type() is not Object, the \l {QJsonObject::}{QJsonObject()} will be returned.

Definition at line 781 of file qjsonvalue.cpp.

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◆ toObject() [2/2]

QJsonObject QJsonValue::toObject ( const QJsonObject & defaultValue ) const

Converts the value to an object and returns it.

If type() is not Object, the defaultValue will be returned.

Definition at line 764 of file qjsonvalue.cpp.

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◆ toString() [1/2]

QString QJsonValue::toString ( ) const

Converts the value to a QString and returns it.

If type() is not String, a null QString will be returned.

See also: QString::isNull()

Definition at line 727 of file qjsonvalue.cpp.

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◆ toString() [2/2]

QString QJsonValue::toString ( const QString & defaultValue ) const

Converts the value to a QString and returns it.

If type() is not String, the defaultValue will be returned.

Definition at line 715 of file qjsonvalue.cpp.

◆ toVariant()

QVariant QJsonValue::toVariant ( ) const

Converts the value to a \l {QVariant::}{QVariant()}.

The QJsonValue types will be converted as follows:

\value Null QMetaType::Nullptr \value Bool QMetaType::Bool \value Double QMetaType::Double or QMetaType::LongLong \value String QString \value Array QVariantList \value Object QVariantMap \value Undefined \l {QVariant::}{QVariant()}

See also: fromVariant()

Definition at line 560 of file qjsonvalue.cpp.

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◆ type()

QJsonValue::Type QJsonValue::type ( ) const

Returns the type of the value.

See also: QJsonValue::Type

Definition at line 608 of file qjsonvalue.cpp.

Friends And Related Function Documentation

◆ operator<< [1/2]

Q_CORE_EXPORT QDataStream& operator<<	(	QDataStream &	,
		const QJsonValue &
	)

friend

Definition at line 1023 of file qjsonvalue.cpp.

◆ operator<< [2/2]

Q_CORE_EXPORT QDebug operator<<	(	QDebug	,
		const QJsonValue &
	)

friend

Definition at line 982 of file qjsonvalue.cpp.

◆ QCborValue

friend class QCborValue

friend

Definition at line 142 of file qjsonvalue.h.

◆ QJsonArray

friend class QJsonArray

friend

Definition at line 140 of file qjsonvalue.h.

◆ QJsonObject

friend class QJsonObject

friend

Definition at line 141 of file qjsonvalue.h.

◆ QJsonPrivate::Value

friend class QJsonPrivate::Value

friend

Definition at line 139 of file qjsonvalue.h.

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

src/corelib/serialization/qjsonvalue.h
src/corelib/serialization/qjsonvalue.cpp

Public Types

Public Member Functions

Static Public Member Functions

Friends

Detailed Description

Member Enumeration Documentation

◆ Type

Constructor & Destructor Documentation

◆ QJsonValue() [1/14]

◆ QJsonValue() [2/14]

◆ QJsonValue() [3/14]

◆ QJsonValue() [4/14]

◆ QJsonValue() [5/14]

◆ QJsonValue() [6/14]

◆ QJsonValue() [7/14]

◆ QJsonValue() [8/14]

◆ QJsonValue() [9/14]

◆ QJsonValue() [10/14]

◆ QJsonValue() [11/14]

◆ QJsonValue() [12/14]

◆ ~QJsonValue()

◆ QJsonValue() [13/14]

◆ QJsonValue() [14/14]

Member Function Documentation

◆ fromVariant()

◆ isArray()

◆ isBool()

◆ isDouble()

◆ isNull()

◆ isObject()

◆ isString()

◆ isUndefined()

◆ operator!=()

◆ operator=() [1/2]

◆ operator=() [2/2]

◆ operator==()

◆ operator[]() [1/4]

◆ operator[]() [2/4]

◆ operator[]() [3/4]

◆ operator[]() [4/4]

◆ swap()

◆ toArray() [1/2]

◆ toArray() [2/2]

◆ toBool()

◆ toDouble()

◆ toInt()

◆ toInteger()

◆ toObject() [1/2]

◆ toObject() [2/2]

◆ toString() [1/2]

◆ toString() [2/2]

◆ toVariant()

◆ type()

Friends And Related Function Documentation

◆ operator<< [1/2]

◆ operator<< [2/2]

◆ QCborValue

◆ QJsonArray

◆ QJsonObject

◆ QJsonPrivate::Value