class QDataStream

The QDataStream class provides serialization of binary data to a QIODevice . More

Inheritance diagram of PySide6.QtCore.QDataStream

Synopsis

Methods

Note

This documentation may contain snippets that were automatically translated from C++ to Python. We always welcome contributions to the snippet translation. If you see an issue with the translation, you can also let us know by creating a ticket on https:/bugreports.qt.io/projects/PYSIDE

Detailed Description

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

A data stream is a binary stream of encoded information which is 100% independent of the host computer’s operating system, CPU or byte order. For example, a data stream that is written by a PC under Windows can be read by a Sun SPARC running Solaris.

You can also use a data stream to read/write raw unencoded binary data . If you want a “parsing” input stream, see QTextStream .

The QDataStream class implements the serialization of C++’s basic data types, like char, short, int, char *, etc. Serialization of more complex data is accomplished by breaking up the data into primitive units.

A data stream cooperates closely with a QIODevice . A QIODevice represents an input/output medium one can read data from and write data to. The QFile class is an example of an I/O device.

Example (write binary data to a stream):

file = QFile("file.dat")
file.open(QIODevice.WriteOnly)
QDataStream out(file) # we will serialize the data into the file
out << QString("the answer is") # serialize a string
out << (qint32)42 # serialize an integer

Example (read binary data from a stream):

file = QFile("file.dat")
file.open(QIODevice.ReadOnly)
QDataStream in(file) # read the data serialized from the file
str = QString()
a = qint32()
in >> str >> a # extract "the answer is" and 42

Each item written to the stream is written in a predefined binary format that varies depending on the item’s type. Supported Qt types include QBrush, QColor, QDateTime , QFont, QPixmap, QString , QVariant and many others. For the complete list of all Qt types supporting data streaming see Serializing Qt Data Types .

For integers it is best to always cast to a Qt integer type for writing, and to read back into the same Qt integer type. This ensures that you get integers of the size you want and insulates you from compiler and platform differences.

Enumerations can be serialized through QDataStream without the need of manually defining streaming operators. Enum classes are serialized using the declared size.

The initial I/O device is usually set in the constructor, but can be changed with setDevice() . If you’ve reached the end of the data (or if there is no I/O device set) atEnd() will return true.

Serializing containers and strings

The serialization format is a length specifier first, then l bytes of data. The length specifier is one quint32 if the version is less than 6.7 or if the number of elements is less than 0xfffffffe (2^32 -2). Otherwise there is an extend value 0xfffffffe followed by one quint64 with the actual value. In addition for containers that support isNull(), it is encoded as a single quint32 with all bits set and no data.

To take one example, if the string size fits into 32 bits, a char * string is written as a 32-bit integer equal to the length of the string, including the ‘\0’ byte, followed by all the characters of the string, including the ‘\0’ byte. If the string size is greater, the value 0xffffffffe is written as a marker of an extended size, followed by 64 bits of the actual size. When reading a char * string, 4 bytes are read first. If the value is not equal to 0xffffffffe (the marker of extended size), then these 4 bytes are treated as the 32 bit size of the string. Otherwise, the next 8 bytes are read and treated as a 64 bit size of the string. Then, all the characters for the char * string, including the ‘\0’ terminator, are read.

Versioning

QDataStream ‘s binary format has evolved since Qt 1.0, and is likely to continue evolving to reflect changes done in Qt. When inputting or outputting complex types, it’s very important to make sure that the same version of the stream ( version() ) is used for reading and writing. If you need both forward and backward compatibility, you can hardcode the version number in the application:

stream.setVersion(QDataStream.Qt_4_0)

If you are producing a new binary data format, such as a file format for documents created by your application, you could use a QDataStream to write the data in a portable format. Typically, you would write a brief header containing a magic string and a version number to give yourself room for future expansion. For example:

file = QFile("file.xxx")
file.open(QIODevice.WriteOnly)
out = QDataStream(file)
# Write a header with a "magic number" and a version
out << (quint32)0xA0B0C0D0
out << (qint32)123
out.setVersion(QDataStream.Qt_4_0)
# Write the data
out << lots_of_interesting_data

Then read it in with:

file = QFile("file.xxx")
file.open(QIODevice.ReadOnly)
in = QDataStream(file)
# Read and check the header
magic = quint32()
in >> magic
if magic != 0xA0B0C0D0:
    return XXX_BAD_FILE_FORMAT
# Read the version
version = qint32()
in >> version
if version < 100:
    return XXX_BAD_FILE_TOO_OLD
if version > 123:
    return XXX_BAD_FILE_TOO_NEW
if version <= 110:
    in.setVersion(QDataStream.Qt_3_2)
else:
    in.setVersion(QDataStream.Qt_4_0)
# Read the data
in >> lots_of_interesting_data
if version >= 120:
    in >> data_new_in_XXX_version_1_2
in >> other_interesting_data

You can select which byte order to use when serializing data. The default setting is big-endian (MSB first). Changing it to little-endian breaks the portability (unless the reader also changes to little-endian). We recommend keeping this setting unless you have special requirements.

Reading and Writing Raw Binary Data

You may wish to read/write your own raw binary data to/from the data stream directly. Data may be read from the stream into a preallocated char * using readRawData() . Similarly data can be written to the stream using writeRawData() . Note that any encoding/decoding of the data must be done by you.

A similar pair of functions is readBytes() and writeBytes() . These differ from their raw counterparts as follows: readBytes() reads a quint32 which is taken to be the length of the data to be read, then that number of bytes is read into the preallocated char *; writeBytes() writes a quint32 containing the length of the data, followed by the data. Note that any encoding/decoding of the data (apart from the length quint32) must be done by you.

Reading and Writing Qt Collection Classes

The Qt container classes can also be serialized to a QDataStream . These include QList , QSet , QHash , and QMap . The stream operators are declared as non-members of the classes.

Reading and Writing Other Qt Classes

In addition to the overloaded stream operators documented here, any Qt classes that you might want to serialize to a QDataStream will have appropriate stream operators declared as non-member of the class:

operator<< = QDataStream(QDataStream , QXxx )
operator>> = QDataStream(QDataStream , QXxx )

For example, here are the stream operators declared as non-members of the QImage class:

operator<< = QDataStream(QDataStream stream, QImage image)
operator>> = QDataStream(QDataStream stream, QImage image)

To see if your favorite Qt class has similar stream operators defined, check the Related Non-Members section of the class’s documentation page.

Using Read Transactions

When a data stream operates on an asynchronous device, the chunks of data can arrive at arbitrary points in time. The QDataStream class implements a transaction mechanism that provides the ability to read the data atomically with a series of stream operators. As an example, you can handle incomplete reads from a socket by using a transaction in a slot connected to the readyRead() signal:

in.startTransaction()
str = QString()
a = qint32()
in >> str >> a # try to read packet atomically
if not in.commitTransaction():
    return # wait for more data

If no full packet is received, this code restores the stream to the initial position, after which you need to wait for more data to arrive.

Corruption and Security

QDataStream is not resilient against corrupted data inputs and should therefore not be used for security-sensitive situations, even when using transactions. Transactions will help determine if a valid input can currently be decoded with the data currently available on an asynchronous device, but will assume that the data that is available is correctly formed.

Additionally, many QDataStream demarshalling operators will allocate memory based on information found in the stream. Those operators perform no verification on whether the requested amount of memory is reasonable or if it is compatible with the amount of data available in the stream (example: demarshalling a QByteArray or QString may see the request for allocation of several gigabytes of data).

QDataStream should not be used on content whose provenance cannot be trusted. Applications should be designed to attempt to decode only streams whose provenance is at least as trustworthy as that of the application itself or its plugins.

See also

QTextStream QVariant

class Version

(inherits enum.IntEnum) This enum provides symbolic synonyms for the data serialization format version numbers.

Constant

Description

QDataStream.Qt_1_0

Version 1 (Qt 1.x)

QDataStream.Qt_2_0

Version 2 (Qt 2.0)

QDataStream.Qt_2_1

Version 3 (Qt 2.1, 2.2, 2.3)

QDataStream.Qt_3_0

Version 4 (Qt 3.0)

QDataStream.Qt_3_1

Version 5 (Qt 3.1, 3.2)

QDataStream.Qt_3_3

Version 6 (Qt 3.3)

QDataStream.Qt_4_0

Version 7 (Qt 4.0, Qt 4.1)

QDataStream.Qt_4_1

Version 7 (Qt 4.0, Qt 4.1)

QDataStream.Qt_4_2

Version 8 (Qt 4.2)

QDataStream.Qt_4_3

Version 9 (Qt 4.3)

QDataStream.Qt_4_4

Version 10 (Qt 4.4)

QDataStream.Qt_4_5

Version 11 (Qt 4.5)

QDataStream.Qt_4_6

Version 12 (Qt 4.6, Qt 4.7, Qt 4.8)

QDataStream.Qt_4_7

Same as Qt_4_6.

QDataStream.Qt_4_8

Same as Qt_4_6.

QDataStream.Qt_4_9

Same as Qt_4_6.

QDataStream.Qt_5_0

Version 13 (Qt 5.0)

QDataStream.Qt_5_1

Version 14 (Qt 5.1)

QDataStream.Qt_5_2

Version 15 (Qt 5.2)

QDataStream.Qt_5_3

Same as Qt_5_2

QDataStream.Qt_5_4

Version 16 (Qt 5.4)

QDataStream.Qt_5_5

Same as Qt_5_4

QDataStream.Qt_5_6

Version 17 (Qt 5.6)

QDataStream.Qt_5_7

Same as Qt_5_6

QDataStream.Qt_5_8

Same as Qt_5_6

QDataStream.Qt_5_9

Same as Qt_5_6

QDataStream.Qt_5_10

Same as Qt_5_6

QDataStream.Qt_5_11

Same as Qt_5_6

QDataStream.Qt_5_12

Version 18 (Qt 5.12)

QDataStream.Qt_5_13

Version 19 (Qt 5.13)

QDataStream.Qt_5_14

Same as Qt_5_13

QDataStream.Qt_5_15

Same as Qt_5_13

QDataStream.Qt_6_0

Version 20 (Qt 6.0)

QDataStream.Qt_6_1

Same as Qt_6_0

QDataStream.Qt_6_2

Same as Qt_6_0

QDataStream.Qt_6_3

Same as Qt_6_0

QDataStream.Qt_6_4

Same as Qt_6_0

QDataStream.Qt_6_5

Same as Qt_6_0

QDataStream.Qt_6_6

Version 21 (Qt 6.6)

QDataStream.Qt_6_7

Version 22 (Qt 6.7)

QDataStream.Qt_6_8

Same as Qt_6_7

class ByteOrder

The byte order used for reading/writing the data.

Constant

Description

QDataStream.BigEndian

Most significant byte first (the default)

QDataStream.LittleEndian

Least significant byte first

class Status

This enum describes the current status of the data stream.

Constant

Description

QDataStream.Ok

The data stream is operating normally.

QDataStream.ReadPastEnd

The data stream has read past the end of the data in the underlying device.

QDataStream.ReadCorruptData

The data stream has read corrupt data.

QDataStream.WriteFailed

The data stream cannot write to the underlying device.

QDataStream.SizeLimitExceeded

The data stream cannot read or write the data because its size is larger than supported by the current platform. This can happen, for example, when trying to read more that 2 GiB of data on a 32-bit platform.

class FloatingPointPrecision

The precision of floating point numbers used for reading/writing the data. This will only have an effect if the version of the data stream is Qt_4_6 or higher.

Warning

The floating point precision must be set to the same value on the object that writes and the object that reads the data stream.

Constant

Description

QDataStream.SinglePrecision

All floating point numbers in the data stream have 32-bit precision.

QDataStream.DoublePrecision

All floating point numbers in the data stream have 64-bit precision.

Added in version 4.6.

__init__()

Constructs a data stream that has no I/O device.

See also

setDevice()

__init__(arg__1)
Parameters:

arg__1QIODevice

Constructs a data stream that uses the I/O device d.

__init__(arg__1)
Parameters:

arg__1QByteArray

Constructs a read-only data stream that operates on byte array a. Use QDataStream ( QByteArray *, int) if you want to write to a byte array.

Since QByteArray is not a QIODevice subclass, internally a QBuffer is created to wrap the byte array.

__init__(arg__1, flags)
Parameters:

Constructs a data stream that operates on a byte array, a. The mode describes how the device is to be used.

Alternatively, you can use QDataStream (const QByteArray &) if you just want to read from a byte array.

Since QByteArray is not a QIODevice subclass, internally a QBuffer is created to wrap the byte array.

abortTransaction()

Aborts a read transaction.

This function is commonly used to discard the transaction after higher-level protocol errors or loss of stream synchronization.

If called on an inner transaction, aborting is delegated to the outermost transaction, and subsequently started inner transactions are forced to fail.

For the outermost transaction, discards the restoration point and any internally duplicated data of the stream. Will not affect the current read position of the stream.

Sets the status of the data stream to

atEnd()
Return type:

bool

Returns true if the I/O device has reached the end position (end of the stream or file) or if there is no I/O device set; otherwise returns false.

See also

atEnd()

byteOrder()
Return type:

ByteOrder

Returns the current byte order setting – either BigEndian or LittleEndian .

See also

setByteOrder()

commitTransaction()
Return type:

bool

Completes a read transaction. Returns true if no read errors have occurred during the transaction; otherwise returns false.

If called on an inner transaction, committing will be postponed until the outermost commitTransaction(), rollbackTransaction() , or abortTransaction() call occurs.

Otherwise, if the stream status indicates reading past the end of the data, this function restores the stream data to the point of the startTransaction() call. When this situation occurs, you need to wait for more data to arrive, after which you start a new transaction. If the data stream has read corrupt data or any of the inner transactions was aborted, this function aborts the transaction.

device()
Return type:

QIODevice

Returns the I/O device currently set, or None if no device is currently set.

See also

setDevice()

floatingPointPrecision()
Return type:

FloatingPointPrecision

Returns the floating point precision of the data stream.

isDeviceTransactionStarted()
Return type:

bool

__lshift__(st)
Parameters:

stQCborSimpleType

Return type:

QDataStream

__lshift__(arg__2)
Parameters:

arg__2QChar

Return type:

QDataStream

__lshift__(arg__2)
Parameters:

arg__2QDate

Return type:

QDataStream

__lshift__(attr)
Parameters:

attrAttribute

Return type:

QDataStream

__lshift__(combination)
Parameters:

combinationQKeyCombination

Return type:

QDataStream

__lshift__(arg__2)
Parameters:

arg__2QTime

Return type:

QDataStream

__lshift__(arg__2)
Parameters:

arg__2QVector2D

Return type:

QDataStream

__lshift__(arg__2)
Parameters:

arg__2QVector3D

Return type:

QDataStream

__lshift__(arg__2)
Parameters:

arg__2QVector4D

Return type:

QDataStream

__lshift__(i)
Parameters:

i – int

Return type:

QDataStream

__lshift__(arg__2)
Parameters:

arg__2QBitArray

Return type:

QDataStream

__lshift__(uuid)
Parameters:

uuidQBluetoothUuid

Return type:

QDataStream

__lshift__(arg__2)
Parameters:

arg__2QBrush

Return type:

QDataStream

__lshift__(arg__2)
Parameters:

arg__2QByteArray

Return type:

QDataStream

__lshift__(arg__2)
Parameters:

arg__2QCanBusFrame

Return type:

QDataStream

__lshift__(arg__2)
Parameters:

arg__2QCborArray

Return type:

QDataStream

__lshift__(arg__2)
Parameters:

arg__2QCborMap

Return type:

QDataStream

__lshift__(arg__2)
Parameters:

arg__2QCborValue

Return type:

QDataStream

__lshift__(arg__2)
Parameters:

arg__2QColor

Return type:

QDataStream

__lshift__(arg__2)
Parameters:

arg__2QColorSpace

Return type:

QDataStream

__lshift__(cursor)
Parameters:

cursorQCursor

Return type:

QDataStream

__lshift__(arg__2)
Parameters:

arg__2QDateTime

Return type:

QDataStream

__lshift__(arg__2)
Parameters:

arg__2QEasingCurve

Return type:

QDataStream

__lshift__(arg__2)
Parameters:

arg__2QFont

Return type:

QDataStream

__lshift__(monitor)
Parameters:

monitorQGeoAreaMonitorInfo

Return type:

QDataStream

__lshift__(circle)
Parameters:

circleQGeoCircle

Return type:

QDataStream

__lshift__(coordinate)
Parameters:

coordinateQGeoCoordinate

Return type:

QDataStream

__lshift__(path)
Parameters:

pathQGeoPath

Return type:

QDataStream

__lshift__(polygon)
Parameters:

polygonQGeoPolygon

Return type:

QDataStream

__lshift__(info)
Parameters:

infoQGeoPositionInfo

Return type:

QDataStream

__lshift__(rectangle)
Parameters:

rectangleQGeoRectangle

Return type:

QDataStream

__lshift__(info)
Parameters:

infoQGeoSatelliteInfo

Return type:

QDataStream

__lshift__(shape)
Parameters:

shapeQGeoShape

Return type:

QDataStream

__lshift__(arg__2)
Parameters:

arg__2QHostAddress

Return type:

QDataStream

__lshift__(arg__2)
Parameters:

arg__2QIcon

Return type:

QDataStream

__lshift__(arg__2)
Parameters:

arg__2QImage

Return type:

QDataStream

__lshift__(arg__2)
Parameters:

arg__2QJSValue

Return type:

QDataStream

__lshift__(arg__2)
Parameters:

arg__2QJsonArray

Return type:

QDataStream

__lshift__(arg__2)
Parameters:

arg__2QJsonDocument

Return type:

QDataStream

__lshift__(arg__2)
Parameters:

arg__2QJsonObject

Return type:

QDataStream

__lshift__(arg__2)
Parameters:

arg__2QJsonValue

Return type:

QDataStream

__lshift__(ks)
Parameters:

ksQKeySequence

Return type:

QDataStream

__lshift__(arg__2)
Parameters:

arg__2QLine

Return type:

QDataStream

__lshift__(arg__2)
Parameters:

arg__2QLineF

Return type:

QDataStream

__lshift__(item)
Parameters:

itemQListWidgetItem

Return type:

QDataStream

__lshift__(arg__2)
Parameters:

arg__2QLocale

Return type:

QDataStream

__lshift__(arg__2)
Parameters:

arg__2QMargins

Return type:

QDataStream

__lshift__(arg__2)
Parameters:

arg__2QMarginsF

Return type:

QDataStream

__lshift__(arg__2)
Parameters:

arg__2QMatrix4x4

Return type:

QDataStream

__lshift__(pdu)
Parameters:

pduQModbusPdu

Return type:

QDataStream

__lshift__(pdu)
Parameters:

pduQModbusRequest

Return type:

QDataStream

__lshift__(pdu)
Parameters:

pduQModbusResponse

Return type:

QDataStream

__lshift__(arg__2)
Parameters:

arg__2QMqttTopicFilter

Return type:

QDataStream

__lshift__(arg__2)
Parameters:

arg__2QMqttTopicName

Return type:

QDataStream

__lshift__(arg__2)
Parameters:

arg__2QNetworkCacheMetaData

Return type:

QDataStream

__lshift__(arg__2)
Parameters:

arg__2QPageRanges

Return type:

QDataStream

__lshift__(arg__2)
Parameters:

arg__2QPainterPath

Return type:

QDataStream

__lshift__(p)
Parameters:

pQPalette

Return type:

QDataStream

__lshift__(arg__2)
Parameters:

arg__2QPen

Return type:

QDataStream

__lshift__(arg__2)
Parameters:

arg__2QPicture

Return type:

QDataStream

__lshift__(arg__2)
Parameters:

arg__2QPixmap

Return type:

QDataStream

__lshift__(arg__2)
Parameters:

arg__2QPoint

Return type:

QDataStream

__lshift__(arg__2)
Parameters:

arg__2QPointF

Return type:

QDataStream

__lshift__(polygon)
Parameters:

polygonQPolygon

Return type:

QDataStream

__lshift__(array)
Parameters:

arrayQPolygonF

Return type:

QDataStream

__lshift__(arg__2)
Parameters:

arg__2QQuaternion

Return type:

QDataStream

__lshift__(arg__2)
Parameters:

arg__2QRect

Return type:

QDataStream

__lshift__(arg__2)
Parameters:

arg__2QRectF

Return type:

QDataStream

__lshift__(arg__2)
Parameters:

arg__2QRegion

Return type:

QDataStream

__lshift__(re)
Parameters:

reQRegularExpression

Return type:

QDataStream

__lshift__(info)
Parameters:

infoQRemoteObjectSourceLocationInfo

Return type:

QDataStream

__lshift__(arg__2)
Parameters:

arg__2QSize

Return type:

QDataStream

__lshift__(arg__2)
Parameters:

arg__2QSizeF

Return type:

QDataStream

__lshift__(arg__2)
Parameters:

arg__2QSizePolicy

Return type:

QDataStream

__lshift__(item)
Parameters:

itemQStandardItem

Return type:

QDataStream

__lshift__(arg__1)
Parameters:

arg__1 – str

__lshift__(arg__2)
Parameters:

arg__2 – str

Return type:

QDataStream

__lshift__(item)
Parameters:

itemQTableWidgetItem

Return type:

QDataStream

__lshift__(tz)
Parameters:

tzQTimeZone

Return type:

QDataStream

__lshift__(arg__2)
Parameters:

arg__2QTransform

Return type:

QDataStream

__lshift__(item)
Parameters:

itemQTreeWidgetItem

Return type:

QDataStream

__lshift__(arg__2)
Parameters:

arg__2QUrl

Return type:

QDataStream

__lshift__(arg__2)
Parameters:

arg__2QUuid

Return type:

QDataStream

__lshift__(p)
Parameters:

p – object

Return type:

QDataStream

__lshift__(version)
Parameters:

versionQVersionNumber

Return type:

QDataStream

__lshift__(voice)
Parameters:

voiceQVoice

Return type:

QDataStream

__lshift__(history)
Parameters:

historyQWebEngineHistory

Return type:

QDataStream

__rshift__(arg__2)
Parameters:

arg__2QBitArray

Return type:

QDataStream

__rshift__(uuid)
Parameters:

uuidQBluetoothUuid

Return type:

QDataStream

__rshift__(arg__2)
Parameters:

arg__2QBrush

Return type:

QDataStream

__rshift__(arg__2)
Parameters:

arg__2QByteArray

Return type:

QDataStream

__rshift__(arg__2)
Parameters:

arg__2QCanBusFrame

Return type:

QDataStream

__rshift__(arg__2)
Parameters:

arg__2QCborArray

Return type:

QDataStream

__rshift__(arg__2)
Parameters:

arg__2QCborMap

Return type:

QDataStream

__rshift__(st)
Parameters:

stQCborSimpleType

Return type:

QDataStream

__rshift__(arg__2)
Parameters:

arg__2QCborValue

Return type:

QDataStream

__rshift__(arg__2)
Parameters:

arg__2QChar

Return type:

QDataStream

__rshift__(arg__2)
Parameters:

arg__2QColor

Return type:

QDataStream

__rshift__(arg__2)
Parameters:

arg__2QColorSpace

Return type:

QDataStream

__rshift__(cursor)
Parameters:

cursorQCursor

Return type:

QDataStream

__rshift__(arg__2)
Parameters:

arg__2QDate

Return type:

QDataStream

__rshift__(arg__2)
Parameters:

arg__2QDateTime

Return type:

QDataStream

__rshift__(arg__2)
Parameters:

arg__2QEasingCurve

Return type:

QDataStream

__rshift__(arg__2)
Parameters:

arg__2QFont

Return type:

QDataStream

__rshift__(monitor)
Parameters:

monitorQGeoAreaMonitorInfo

Return type:

QDataStream

__rshift__(circle)
Parameters:

circleQGeoCircle

Return type:

QDataStream

__rshift__(coordinate)
Parameters:

coordinateQGeoCoordinate

Return type:

QDataStream

__rshift__(path)
Parameters:

pathQGeoPath

Return type:

QDataStream

__rshift__(polygon)
Parameters:

polygonQGeoPolygon

Return type:

QDataStream

__rshift__(info)
Parameters:

infoQGeoPositionInfo

Return type:

QDataStream

__rshift__(attr)
Parameters:

attrAttribute

Return type:

QDataStream

__rshift__(rectangle)
Parameters:

rectangleQGeoRectangle

Return type:

QDataStream

__rshift__(info)
Parameters:

infoQGeoSatelliteInfo

Return type:

QDataStream

__rshift__(shape)
Parameters:

shapeQGeoShape

Return type:

QDataStream

__rshift__(arg__2)
Parameters:

arg__2QHostAddress

Return type:

QDataStream

__rshift__(arg__2)
Parameters:

arg__2QIcon

Return type:

QDataStream

__rshift__(arg__2)
Parameters:

arg__2QImage

Return type:

QDataStream

__rshift__(arg__2)
Parameters:

arg__2QJSValue

Return type:

QDataStream

__rshift__(arg__2)
Parameters:

arg__2QJsonArray

Return type:

QDataStream

__rshift__(arg__2)
Parameters:

arg__2QJsonDocument

Return type:

QDataStream

__rshift__(arg__2)
Parameters:

arg__2QJsonObject

Return type:

QDataStream

__rshift__(arg__2)
Parameters:

arg__2QJsonValue

Return type:

QDataStream

__rshift__(combination)
Parameters:

combinationQKeyCombination

Return type:

QDataStream

__rshift__(ks)
Parameters:

ksQKeySequence

Return type:

QDataStream

__rshift__(arg__2)
Parameters:

arg__2QLine

Return type:

QDataStream

__rshift__(arg__2)
Parameters:

arg__2QLineF

Return type:

QDataStream

__rshift__(item)
Parameters:

itemQListWidgetItem

Return type:

QDataStream

__rshift__(arg__2)
Parameters:

arg__2QLocale

Return type:

QDataStream

__rshift__(arg__2)
Parameters:

arg__2QMargins

Return type:

QDataStream

__rshift__(arg__2)
Parameters:

arg__2QMarginsF

Return type:

QDataStream

__rshift__(arg__2)
Parameters:

arg__2QMatrix4x4

Return type:

QDataStream

__rshift__(code)
Parameters:

codeFunctionCode

Return type:

QDataStream

__rshift__(pdu)
Parameters:

pduQModbusRequest

Return type:

QDataStream

__rshift__(pdu)
Parameters:

pduQModbusResponse

Return type:

QDataStream

__rshift__(arg__2)
Parameters:

arg__2QMqttTopicFilter

Return type:

QDataStream

__rshift__(arg__2)
Parameters:

arg__2QMqttTopicName

Return type:

QDataStream

__rshift__(arg__2)
Parameters:

arg__2QNetworkCacheMetaData

Return type:

QDataStream

__rshift__(arg__2)
Parameters:

arg__2QPageRanges

Return type:

QDataStream

__rshift__(arg__2)
Parameters:

arg__2QPainterPath

Return type:

QDataStream

__rshift__(p)
Parameters:

pQPalette

Return type:

QDataStream

__rshift__(arg__2)
Parameters:

arg__2QPen

Return type:

QDataStream

__rshift__(arg__2)
Parameters:

arg__2QPicture

Return type:

QDataStream

__rshift__(arg__2)
Parameters:

arg__2QPixmap

Return type:

QDataStream

__rshift__(arg__2)
Parameters:

arg__2QPoint

Return type:

QDataStream

__rshift__(arg__2)
Parameters:

arg__2QPointF

Return type:

QDataStream

__rshift__(polygon)
Parameters:

polygonQPolygon

Return type:

QDataStream

__rshift__(array)
Parameters:

arrayQPolygonF

Return type:

QDataStream

__rshift__(arg__2)
Parameters:

arg__2QQuaternion

Return type:

QDataStream

__rshift__(arg__2)
Parameters:

arg__2QRect

Return type:

QDataStream

__rshift__(arg__2)
Parameters:

arg__2QRectF

Return type:

QDataStream

__rshift__(arg__2)
Parameters:

arg__2QRegion

Return type:

QDataStream

__rshift__(re)
Parameters:

reQRegularExpression

Return type:

QDataStream

__rshift__(info)
Parameters:

infoQRemoteObjectSourceLocationInfo

Return type:

QDataStream

__rshift__(arg__2)
Parameters:

arg__2QSize

Return type:

QDataStream

__rshift__(arg__2)
Parameters:

arg__2QSizeF

Return type:

QDataStream

__rshift__(arg__2)
Parameters:

arg__2QSizePolicy

Return type:

QDataStream

__rshift__(item)
Parameters:

itemQStandardItem

Return type:

QDataStream

__rshift__(arg__2)
Parameters:

arg__2 – str

Return type:

QDataStream

__rshift__(item)
Parameters:

itemQTableWidgetItem

Return type:

QDataStream

__rshift__(arg__2)
Parameters:

arg__2QTime

Return type:

QDataStream

__rshift__(tz)
Parameters:

tzQTimeZone

Return type:

QDataStream

__rshift__(arg__2)
Parameters:

arg__2QTransform

Return type:

QDataStream

__rshift__(item)
Parameters:

itemQTreeWidgetItem

Return type:

QDataStream

__rshift__(arg__2)
Parameters:

arg__2QUrl

Return type:

QDataStream

__rshift__(arg__2)
Parameters:

arg__2QUuid

Return type:

QDataStream

__rshift__(p)
Parameters:

p – object

Return type:

QDataStream

__rshift__(arg__2)
Parameters:

arg__2QVector2D

Return type:

QDataStream

__rshift__(arg__2)
Parameters:

arg__2QVector3D

Return type:

QDataStream

__rshift__(arg__2)
Parameters:

arg__2QVector4D

Return type:

QDataStream

__rshift__(version)
Parameters:

versionQVersionNumber

Return type:

QDataStream

__rshift__(voice)
Parameters:

voiceQVoice

Return type:

QDataStream

__rshift__(history)
Parameters:

historyQWebEngineHistory

Return type:

QDataStream

__rshift__(i)
Parameters:

i – bool

Return type:

QDataStream

Reads a boolean value from the stream into i. Returns a reference to the stream.

__rshift__(i)
Parameters:

ichar

Return type:

QDataStream

readBool()
Return type:

bool

readBytes(len)
Parameters:

lenqint64

Return type:

PyTuple

Reads the buffer s from the stream and returns a reference to the stream.

The buffer s is allocated using new []. Destroy it with the delete [] operator.

The l parameter is set to the length of the buffer. If the string read is empty, l is set to 0 and s is set to None.

The serialization format is a length specifier first, then l bytes of data. The length specifier is one quint32 if the version is less than 6.7 or if the number of elements is less than 0xfffffffe (2^32 -2), otherwise there is an extend value 0xfffffffe followed by one quint64 with the actual value. In addition for containers that support isNull(), it is encoded as a single quint32 with all bits set and no data.

readDouble()
Return type:

float

readFloat()
Return type:

float

readInt16()
Return type:

int

readInt32()
Return type:

int

readInt64()
Return type:

int

readInt8()
Return type:

int

readQChar()
Return type:

QChar

readQString()
Return type:

str

readQStringList()
Return type:

list of strings

readQVariant()
Return type:

object

readRawData(len)
Parameters:

len – int

Return type:

int

Reads at most len bytes from the stream into s and returns the number of bytes read. If an error occurs, this function returns -1.

The buffer s must be preallocated. The data is not decoded.

readString()
Return type:

str

readUInt16()
Return type:

int

readUInt32()
Return type:

int

readUInt64()
Return type:

int

readUInt8()
Return type:

int

resetStatus()

Resets the status of the data stream.

rollbackTransaction()

Reverts a read transaction.

This function is commonly used to rollback the transaction when an incomplete read was detected prior to committing the transaction.

If called on an inner transaction, reverting is delegated to the outermost transaction, and subsequently started inner transactions are forced to fail.

For the outermost transaction, restores the stream data to the point of the startTransaction() call. If the data stream has read corrupt data or any of the inner transactions was aborted, this function aborts the transaction.

If the preceding stream operations were successful, sets the status of the data stream to

setByteOrder(arg__1)
Parameters:

arg__1ByteOrder

Sets the serialization byte order to bo.

The bo parameter can be BigEndian or LittleEndian .

The default setting is big-endian. We recommend leaving this setting unless you have special requirements.

See also

byteOrder()

setDevice(arg__1)
Parameters:

arg__1QIODevice

void QDataStream::setDevice( QIODevice *d)

Sets the I/O device to d, which can be None to unset to current I/O device.

See also

device()

setFloatingPointPrecision(precision)
Parameters:

precisionFloatingPointPrecision

Sets the floating point precision of the data stream to precision. If the floating point precision is DoublePrecision and the version of the data stream is Qt_4_6 or higher, all floating point numbers will be written and read with 64-bit precision. If the floating point precision is SinglePrecision and the version is Qt_4_6 or higher, all floating point numbers will be written and read with 32-bit precision.

For versions prior to Qt_4_6 , the precision of floating point numbers in the data stream depends on the stream operator called.

The default is DoublePrecision .

Note that this property does not affect the serialization or deserialization of qfloat16 instances.

Warning

This property must be set to the same value on the object that writes and the object that reads the data stream.

setStatus(status)
Parameters:

statusStatus

Sets the status of the data stream to the status given.

Subsequent calls to setStatus() are ignored until resetStatus() is called.

setVersion(arg__1)
Parameters:

arg__1 – int

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

Sets the version number of the data serialization format to v, a value of the Version enum.

You don’t have to set a version if you are using the current version of Qt, but for your own custom binary formats we recommend that you do; see Versioning in the Detailed Description.

To accommodate new functionality, the datastream serialization format of some Qt classes has changed in some versions of Qt. If you want to read data that was created by an earlier version of Qt, or write data that can be read by a program that was compiled with an earlier version of Qt, use this function to modify the serialization format used by QDataStream .

The Version enum provides symbolic constants for the different versions of Qt. For example:

out = QDataStream(file)
out.setVersion(QDataStream.Qt_4_0)

See also

version() Version

skipRawData(len)
Parameters:

len – int

Return type:

int

Skips len bytes from the device. Returns the number of bytes actually skipped, or -1 on error.

This is equivalent to calling readRawData() on a buffer of length len and ignoring the buffer.

See also

seek()

startTransaction()

Starts a new read transaction on the stream.

Defines a restorable point within the sequence of read operations. For sequential devices, read data will be duplicated internally to allow recovery in case of incomplete reads. For random-access devices, this function saves the current position of the stream. Call commitTransaction() , rollbackTransaction() , or abortTransaction() to finish the current transaction.

Once a transaction is started, subsequent calls to this function will make the transaction recursive. Inner transactions act as agents of the outermost transaction (i.e., report the status of read operations to the outermost transaction, which can restore the position of the stream).

Note

Restoring to the point of the nested startTransaction() call is not supported.

When an error occurs during a transaction (including an inner transaction failing), reading from the data stream is suspended (all subsequent read operations return empty/zero values) and subsequent inner transactions are forced to fail. Starting a new outermost transaction recovers from this state. This behavior makes it unnecessary to error-check every read operation separately.

status()
Return type:

Status

Returns the status of the data stream.

version()
Return type:

int

Returns the version number of the data serialization format.

writeBool(arg__1)
Parameters:

arg__1 – bool

writeBytes(arg__1)
Parameters:

arg__1 – str

Return type:

QDataStream

Writes the length specifier len and the buffer s to the stream and returns a reference to the stream.

The len is serialized as a quint32 and an optional quint64, followed by len bytes from s. Note that the data is not encoded.

writeDouble(arg__1)
Parameters:

arg__1 – float

writeFloat(arg__1)
Parameters:

arg__1 – float

writeInt16(arg__1)
Parameters:

arg__1 – int

writeInt32(arg__1)
Parameters:

arg__1 – int

writeInt64(arg__1)
Parameters:

arg__1 – int

writeInt8(arg__1)
Parameters:

arg__1 – int

writeQChar(arg__1)
Parameters:

arg__1QChar

writeQString(arg__1)
Parameters:

arg__1 – str

writeQStringList(arg__1)
Parameters:

arg__1 – list of strings

writeQVariant(arg__1)
Parameters:

arg__1 – object

writeRawData(arg__1)
Parameters:

arg__1PyBuffer

writeRawData(arg__1)
Parameters:

arg__1 – str

Return type:

int

Writes len bytes from s to the stream. Returns the number of bytes actually written, or -1 on error. The data is not encoded.

writeString(arg__1)
Parameters:

arg__1 – str

writeUInt16(arg__1)
Parameters:

arg__1 – int

writeUInt32(arg__1)
Parameters:

arg__1 – int

writeUInt64(arg__1)
Parameters:

arg__1 – int

writeUInt8(arg__1)
Parameters:

arg__1 – int