QJsonDocument

The QJsonDocument class provides a way to read and write JSON documents. More…

Inheritance diagram of PySide2.QtCore.QJsonDocument

Synopsis

Functions

Static functions

Detailed Description

QJsonDocument is a class that wraps a complete JSON document and can read and write this document both from a UTF-8 encoded text based representation as well as Qt’s own binary format.

A JSON document can be converted from its text-based representation to a QJsonDocument using fromJson() . toJson() converts it back to text. The parser is very fast and efficient and converts the JSON to the binary representation used by Qt.

Validity of the parsed document can be queried with ! isNull()

A document can be queried as to whether it contains an array or an object using isArray() and isObject() . The array or object contained in the document can be retrieved using array() or object() and then read or manipulated.

A document can also be created from a stored binary representation using fromBinaryData() or fromRawData() .

See also

JSON Support in Qt JSON Save Game Example

class PySide2.QtCore.QJsonDocument

PySide2.QtCore.QJsonDocument(array)

PySide2.QtCore.QJsonDocument(other)

PySide2.QtCore.QJsonDocument(object)

param array:

PySide2.QtCore.QJsonArray

param other:

PySide2.QtCore.QJsonDocument

param object:

QJsonObject

Constructs an empty and invalid document.

PySide2.QtCore.QJsonDocument.DataValidation

This value is used to tell QJsonDocument whether to validate the binary data when converting to a QJsonDocument using fromBinaryData() or fromRawData() .

Constant

Description

QJsonDocument.Validate

Validate the data before using it. This is the default.

QJsonDocument.BypassValidation

Bypasses data validation. Only use if you received the data from a trusted place and know it’s valid, as using of invalid data can crash the application.
PySide2.QtCore.QJsonDocument.JsonFormat

This value defines the format of the JSON byte array produced when converting to a QJsonDocument using toJson() .

Constant

Description

QJsonDocument.Indented

Defines human readable output as follows:

{
    "Array": [
        true,
        999,
        "string"
    ],
    "Key": "Value",
    "null": null
}

QJsonDocument.Compact

Defines a compact output as follows:

{"Array":[true,999,"string"],"Key":"Value","null":null}
PySide2.QtCore.QJsonDocument.array()
Return type:

PySide2.QtCore.QJsonArray

Returns the QJsonArray contained in the document.

Returns an empty array if the document contains an object.

See also

isArray() object() setArray()

static PySide2.QtCore.QJsonDocument.fromBinaryData(data[, validation=Validate])
Parameters:
Return type:

PySide2.QtCore.QJsonDocument

Note

This function is deprecated.

Creates a QJsonDocument from data .

validation decides whether the data is checked for validity before being used. By default the data is validated. If the data is not valid, the method returns a null document.

Note

Deprecated in Qt 5.15. The binary JSON encoding is only retained for backwards compatibility. It is undocumented and restrictive in the maximum size of JSON documents that can be encoded. Qt JSON types can be converted to Qt CBOR types, which can in turn be serialized into the CBOR binary format and vice versa. The CBOR format is a well-defined and less restrictive binary representation for a superset of JSON.

See also

toBinaryData() fromRawData() isNull() DataValidation QCborValue

static PySide2.QtCore.QJsonDocument.fromJson(json[, error=None])
Parameters:
Return type:

PySide2.QtCore.QJsonDocument

Parses json as a UTF-8 encoded JSON document, and creates a QJsonDocument from it.

Returns a valid (non-null) QJsonDocument if the parsing succeeds. If it fails, the returned document will be null, and the optional error variable will contain further details about the error.

See also

toJson() QJsonParseError isNull()

static PySide2.QtCore.QJsonDocument.fromRawData(data, size[, validation=Validate])
Parameters:
Return type:

PySide2.QtCore.QJsonDocument

Note

This function is deprecated.

Creates a QJsonDocument that uses the first size bytes from data . It assumes data contains a binary encoded JSON document. The created document does not take ownership of data . The data is copied into a different data structure, and the original data can be deleted or modified afterwards.

data has to be aligned to a 4 byte boundary.

validation decides whether the data is checked for validity before being used. By default the data is validated. If the data is not valid, the method returns a null document.

Returns a QJsonDocument representing the data.

Note

Deprecated in Qt 5.15. The binary JSON encoding is only retained for backwards compatibility. It is undocumented and restrictive in the maximum size of JSON documents that can be encoded. Qt JSON types can be converted to Qt CBOR types, which can in turn be serialized into the CBOR binary format and vice versa. The CBOR format is a well-defined and less restrictive binary representation for a superset of JSON.

Note

Before Qt 5.15, the caller had to guarantee that data would not be deleted or modified as long as any QJsonDocument , QJsonObject or QJsonArray still referenced the data. From Qt 5.15 on, this is not necessary anymore.

See also

rawData() fromBinaryData() isNull() DataValidation QCborValue

static PySide2.QtCore.QJsonDocument.fromVariant(variant)
Parameters:

variant – object

Return type:

PySide2.QtCore.QJsonDocument

Creates a QJsonDocument from the QVariant variant .

If the variant contains any other type than a QVariantMap , QVariantHash , QVariantList or QStringList , the returned document is invalid.

See also

toVariant()

PySide2.QtCore.QJsonDocument.isArray()
Return type:

bool

Returns true if the document contains an array.

See also

array() isObject()

PySide2.QtCore.QJsonDocument.isEmpty()
Return type:

bool

Returns true if the document doesn’t contain any data.

PySide2.QtCore.QJsonDocument.isNull()
Return type:

bool

returns true if this document is null.

Null documents are documents created through the default constructor.

Documents created from UTF-8 encoded text or the binary format are validated during parsing. If validation fails, the returned document will also be null.

PySide2.QtCore.QJsonDocument.isObject()
Return type:

bool

Returns true if the document contains an object.

See also

object() isArray()

PySide2.QtCore.QJsonDocument.object()
Return type:

QJsonObject

Returns the QJsonObject contained in the document.

Returns an empty object if the document contains an array.

See also

isObject() array() setObject()

PySide2.QtCore.QJsonDocument.__ne__(other)
Parameters:

other – PySide2.QtCore.QJsonDocument

Return type:

bool

returns true if other is not equal to this document

PySide2.QtCore.QJsonDocument.__eq__(other)
Parameters:

other – PySide2.QtCore.QJsonDocument

Return type:

bool

Returns true if the other document is equal to this document.

PySide2.QtCore.QJsonDocument.operator[](key)
Parameters:

key – str

Return type:

PySide2.QtCore.QJsonValue

PySide2.QtCore.QJsonDocument.operator[](i)
Parameters:

i – int

Return type:

PySide2.QtCore.QJsonValue

Returns a QJsonValue representing the value for index i .

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

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

See also

QJsonValue isUndefined() QJsonArray

PySide2.QtCore.QJsonDocument.rawData(size)
Parameters:

size – int

Return type:

str

Note

This function is deprecated.

Returns the raw binary representation of the data size will contain the size of the returned data.

This method is useful to e.g. stream the JSON document in its binary form to a file.

Note

Deprecated in Qt 5.15. The binary JSON encoding is only retained for backwards compatibility. It is undocumented and restrictive in the maximum size of JSON documents that can be encoded. Qt JSON types can be converted to Qt CBOR types, which can in turn be serialized into the CBOR binary format and vice versa. The CBOR format is a well-defined and less restrictive binary representation for a superset of JSON.

See also

QCborValue

PySide2.QtCore.QJsonDocument.setArray(array)
Parameters:

array – PySide2.QtCore.QJsonArray

Sets array as the main object of this document.

See also

setObject() array()

PySide2.QtCore.QJsonDocument.setObject(object)
Parameters:

object – QJsonObject

Sets object as the main object of this document.

See also

setArray() object()

PySide2.QtCore.QJsonDocument.swap(other)
Parameters:

other – PySide2.QtCore.QJsonDocument

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

PySide2.QtCore.QJsonDocument.toBinaryData()
Return type:

PySide2.QtCore.QByteArray

Note

This function is deprecated.

Returns a binary representation of the document.

The binary representation is also the native format used internally in Qt, and is very efficient and fast to convert to and from.

The binary format can be stored on disk and interchanged with other applications or computers. fromBinaryData() can be used to convert it back into a JSON document.

Note

Deprecated in Qt 5.15. The binary JSON encoding is only retained for backwards compatibility. It is undocumented and restrictive in the maximum size of JSON documents that can be encoded. Qt JSON types can be converted to Qt CBOR types, which can in turn be serialized into the CBOR binary format and vice versa. The CBOR format is a well-defined and less restrictive binary representation for a superset of JSON.

See also

fromBinaryData() QCborValue

PySide2.QtCore.QJsonDocument.toJson()
Return type:

PySide2.QtCore.QByteArray

Converts the QJsonDocument to an indented, UTF-8 encoded JSON document.

See also

fromJson()

PySide2.QtCore.QJsonDocument.toJson(format)
Parameters:

format – JsonFormat

Return type:

PySide2.QtCore.QByteArray

Converts the QJsonDocument to a UTF-8 encoded JSON document in the provided format .

See also

fromJson() JsonFormat

PySide2.QtCore.QJsonDocument.toVariant()
Return type:

object

Returns a QVariant representing the Json document.

The returned variant will be a QVariantList if the document is a QJsonArray and a QVariantMap if the document is a QJsonObject .

See also

fromVariant() toVariant()