PyQt5 Json解析、创建

何其不顾四月天

发布于 2023-03-10 13:18:59

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发布于 2023-03-10 13:18:59

文章被收录于专栏：Qt&PyQt 四月天的专栏

PyQt5 Json解析、创建

简介

最近做了几个小程序，用到了QJson 相关的一些代码，想着在python下测试一下，折腾一番还是整理出来了。

从C++ 接口知道，QJson 相关接口在QtCore下边。

分别有：

Class name	Description
QJsonDocument	Way to read and write JSON documents
QJsonParseError	Used to report errors during JSON parsing
QJsonObject	Encapsulates a JSON object
QJsonValue	Encapsulates a value in JSON
QJsonArray	Encapsulates a JSON array

PyQt5 支持的json接口如下：

链接：https://www.riverbankcomputing.com/static/Docs/PyQt5/api/qtcore/qtcore-module.html

支持的json 接口如下：

Class name	Description
QJsonDocument	Way to read and write JSON documents
QJsonParseError	Used to report errors during JSON parsing
QJsonValue	Encapsulates a value in JSON

从官方文档来看没有对外暴露的QJsonObject,QJsonValue 接口。但是注意：在QMetaType中，可以看到对外提供的接口包含有QJsonObject 这个方法。

   #QtCore.pyi
class QMetaType(sip.simplewrapper):
    QJsonValue = ... # type: 'QMetaType.Type'
    QJsonObject = ... # type: 'QMetaType.Type'
    QJsonArray = ... # type: 'QMetaType.Type'
    QJsonDocument = ... # type: 'QMetaType.Type'

从QMetaType 类来看，PyQt5 支持QJsonObject,QJsonArray这两个属性。下面就是怎么提取到这两个属性了。

Json解析

思路

同C++一样，解析Json。

1.获取Json数据块，读取文件是QFile打开文件，读取文件数据 jsondata 2.通过QJsonDocument 将json数据序列化转化为 QJsonObject对象 3.对QJsonObject进行处理

源码

1.打开文件

file = QFile("config.json")
file.open(QFile.ReadOnly | QFile.Text)
if file.isOpen() == 1:
    data = file.readAll()

2.进行序列化

def jsonparse(data):
    error = QJsonParseError()
    json = QJsonDocument.fromJson(data,error)  # 通过fromjson 获取 QJsonDocument对象
    return json.object() #将Json数据转为 QJsonObject

3.解析JSON

if file.isOpen() == 1:
    data = file.readAll()
    print(data)
    j = jsonparse(data)
    name = j["name"].toString()
    jarrt = j["attri"].toArray()
    jtype = j["type"].toString()
    print(name,jtype)
    for i in jarrt: #数组解析如下
        items = i.toObject()
        print(items["time"].toString())
#json.contains("name") 判断该属性是否存在

4.处理结果

config.json #文件内容如下

{
    "name":"wq",
    "attri":[
        {"time":"11:00"},
        {"time":"12:00"}
    ],
    "type":"person"
}

处理结果：

python3 json.py 
b'{\n    "name":"wq",\n    "attri":[\n        {"time":"11:00"},\n        {"time":"12:00"}\n    ],\n    "type":"person"\n}'
wq person
11:00
12:00

5.contains 测试

代码修改如下：

    j = jsonparse(data)
    if j.__contains__("names") == 1:
        name = j["name"].toString()
        print(name)
    jarrt = j["attri"].toArray()

输出结果如下：

b'{\n    "name":"wq",\n    "attri":[\n        {"time":"11:00"},\n        {"time":"12:00"}\n    ],\n    "type":"person"\n}'
person
11:00
12:00

将代码修改如下：

    if j.__contains__("name") == 1:
        name = j["name"].toString()
        print(name)
    jarrt = j["attri"].toArray()

执行结果如下：

python3 json.py 
b'{\n    "name":"wq",\n    "attri":[\n        {"time":"11:00"},\n        {"time":"12:00"}\n    ],\n    "type":"person"\n}'
wq
person
11:00
12:00

JSON 创建

回答上诉的一些疑点，没有QJsonObjec对外接口怎么创建Json文件。

通过 QJsonDocument 创建 QJsonObect对象，通过 **.object()**获取QJsonObject对象。

源码

def jsonCreate():
    data = QByteArray()
    json = QJsonDocument.fromJson(data).object() #创建空的QJsonObject对象
    json["name"]="wq"
    json["value"]=5
    jsonarry = QJsonDocument.fromJson(data).array() # 创建空的QJsonArray对象。
    for i in range(0,5):
        jsontems = QJsonDocument.fromJson(data).object()
        jsontems["type"]="win"
        jsontems["value"]=i
        jsonarry.append(jsontems)
    json["items"]=jsonarry
    return json

json = jsonCreate()
outputjson = QJsonDocument(json).toJson(QJsonDocument.Compact)
print(outputjson)

执行结果

b'{"items":[{"type":"win","value":0},{"type":"win","value":1},{"type":"win","value":2},{"type":"win","value":3},{"type":"win","value":4}],"name":"wq","value":5}'

JsonFormat

在Qt中Json对象格式分为两种。缩进型和紧凑型。

QJsonDocument::Indented #缩进型
QJsonDocument::Compact #紧凑型

其中 toJson默认缩进型。即：

outputjson = QJsonDocument(json).toJson()
print(outputjson)

执行结果

b'{\n    "items": [\n        {\n            "type": "win",\n            "value": 0\n        },\n        {\n            "type": "win",\n            "value": 1\n        },\n        {\n            "type": "win",\n            "value": 2\n        },\n        {\n            "type": "win",\n            "value": 3\n        },\n        {\n            "type": "win",\n            "value": 4\n        }\n    ],\n    "name": "wq",\n    "value": 5\n}\n'

或者

outputjson = QJsonDocument(json).toJson(QJsonDocument.Indented)
print(outputjson)

执行结果为:

b'{\n    "items": [\n        {\n            "type": "win",\n            "value": 0\n        },\n        {\n            "type": "win",\n            "value": 1\n        },\n        {\n            "type": "win",\n            "value": 2\n        },\n        {\n            "type": "win",\n            "value": 3\n        },\n        {\n            "type": "win",\n            "value": 4\n        }\n    ],\n    "name": "wq",\n    "value": 5\n}\n'

紧凑型

outputjson = QJsonDocument(json).toJson(QJsonDocument.Compact)
print(outputjson)

执行结果：

b'{"items":[{"type":"win","value":0},{"type":"win","value":1},{"type":"win","value":2},{"type":"win","value":3},{"type":"win","value":4}],"name":"wq","value":5}'

QJsonDocument接口如下

class QJsonDocument(sip.simplewrapper):

    class JsonFormat(int): ...
    Indented = ... # type: 'QJsonDocument.JsonFormat'
    Compact = ... # type: 'QJsonDocument.JsonFormat'

    class DataValidation(int): ...
    Validate = ... # type: 'QJsonDocument.DataValidation'
    BypassValidation = ... # type: 'QJsonDocument.DataValidation'

    @typing.overload
    def __init__(self) -> None: ...
    @typing.overload
    def __init__(self, object: typing.Dict[str, typing.Union['QJsonValue', 'QJsonValue.Type', typing.Iterable['QJsonValue'], bool, int, float, None, str]]) -> None: ...
    @typing.overload
    def __init__(self, array: typing.Iterable['QJsonValue']) -> None: ...
    @typing.overload
    def __init__(self, other: 'QJsonDocument') -> None: ...

    @typing.overload
    def __getitem__(self, key: str) -> 'QJsonValue': ...
    @typing.overload
    def __getitem__(self, i: int) -> 'QJsonValue': ...
    def swap(self, other: 'QJsonDocument') -> None: ...
    def isNull(self) -> bool: ...
    def setArray(self, array: typing.Iterable['QJsonValue']) -> None: ...
    def setObject(self, object: typing.Dict[str, typing.Union['QJsonValue', 'QJsonValue.Type', typing.Iterable['QJsonValue'], bool, int, float, None, str]]) -> None: ...
    def array(self) -> typing.List['QJsonValue']: ...
    def object(self) -> typing.Dict[str, typing.Union['QJsonValue', 'QJsonValue.Type', typing.Iterable['QJsonValue'], bool, int, float, None, str]]: ...
    def isObject(self) -> bool: ...
    def isArray(self) -> bool: ...
    def isEmpty(self) -> bool: ...
    @typing.overload
    def toJson(self) -> QByteArray: ...
    @typing.overload
    def toJson(self, format: 'QJsonDocument.JsonFormat') -> QByteArray: ...
    @staticmethod
    def fromJson(json: typing.Union[QByteArray, bytes, bytearray], error: typing.Optional[QJsonParseError] = ...) -> 'QJsonDocument': ...
    def toVariant(self) -> typing.Any: ...
    @staticmethod
    def fromVariant(variant: typing.Any) -> 'QJsonDocument': ...
    def toBinaryData(self) -> QByteArray: ...
    @staticmethod
    def fromBinaryData(data: typing.Union[QByteArray, bytes, bytearray], validation: 'QJsonDocument.DataValidation' = ...) -> 'QJsonDocument': ...
    def rawData(self) -> typing.Tuple[str, int]: ...
    @staticmethod
    def fromRawData(data: str, size: int, validation: 'QJsonDocument.DataValidation' = ...) -> 'QJsonDocument': ...

QJsonValue接口如下

class QJsonValue(sip.simplewrapper):

    class Type(int): ...
    Null = ... # type: 'QJsonValue.Type'
    Bool = ... # type: 'QJsonValue.Type'
    Double = ... # type: 'QJsonValue.Type'
    String = ... # type: 'QJsonValue.Type'
    Array = ... # type: 'QJsonValue.Type'
    Object = ... # type: 'QJsonValue.Type'
    Undefined = ... # type: 'QJsonValue.Type'

    @typing.overload
    def __init__(self, type: 'QJsonValue.Type' = ...) -> None: ...
    @typing.overload
    def __init__(self, other: typing.Union['QJsonValue', 'QJsonValue.Type', typing.Iterable['QJsonValue'], bool, int, float, None, str]) -> None: ...

    def __hash__(self) -> int: ...
    @typing.overload
    def __getitem__(self, key: str) -> 'QJsonValue': ...
    @typing.overload
    def __getitem__(self, i: int) -> 'QJsonValue': ...
    def swap(self, other: 'QJsonValue') -> None: ...
    @typing.overload
    def toString(self) -> str: ...
    @typing.overload
    def toString(self, defaultValue: str) -> str: ...
    @typing.overload
    def toObject(self) -> typing.Dict[str, typing.Union['QJsonValue', 'QJsonValue.Type', typing.Iterable['QJsonValue'], bool, int, float, None, str]]: ...
    @typing.overload
    def toObject(self, defaultValue: typing.Dict[str, typing.Union['QJsonValue', 'QJsonValue.Type', typing.Iterable['QJsonValue'], bool, int, float, None, str]]) -> typing.Dict[str, typing.Union['QJsonValue', 'QJsonValue.Type', typing.Iterable['QJsonValue'], bool, int, float, None, str]]: ...
    @typing.overload
    def toArray(self) -> typing.List['QJsonValue']: ...
    @typing.overload
    def toArray(self, defaultValue: typing.Iterable['QJsonValue']) -> typing.List['QJsonValue']: ...
    def toDouble(self, defaultValue: float = ...) -> float: ...
    def toInt(self, defaultValue: int = ...) -> int: ...
    def toBool(self, defaultValue: bool = ...) -> bool: ...
    def isUndefined(self) -> bool: ...
    def isObject(self) -> bool: ...
    def isArray(self) -> bool: ...
    def isString(self) -> bool: ...
    def isDouble(self) -> bool: ...
    def isBool(self) -> bool: ...
    def isNull(self) -> bool: ...
    def type(self) -> 'QJsonValue.Type': ...
    def toVariant(self) -> typing.Any: ...
    @staticmethod
    def fromVariant(variant: typing.Any) -> 'QJsonValue': ...

QJsonParseError接口如下

class QJsonParseError(sip.simplewrapper):

    class ParseError(int): ...
    NoError = ... # type: 'QJsonParseError.ParseError'
    UnterminatedObject = ... # type: 'QJsonParseError.ParseError'
    MissingNameSeparator = ... # type: 'QJsonParseError.ParseError'
    UnterminatedArray = ... # type: 'QJsonParseError.ParseError'
    MissingValueSeparator = ... # type: 'QJsonParseError.ParseError'
    IllegalValue = ... # type: 'QJsonParseError.ParseError'
    TerminationByNumber = ... # type: 'QJsonParseError.ParseError'
    IllegalNumber = ... # type: 'QJsonParseError.ParseError'
    IllegalEscapeSequence = ... # type: 'QJsonParseError.ParseError'
    IllegalUTF8String = ... # type: 'QJsonParseError.ParseError'
    UnterminatedString = ... # type: 'QJsonParseError.ParseError'
    MissingObject = ... # type: 'QJsonParseError.ParseError'
    DeepNesting = ... # type: 'QJsonParseError.ParseError'
    DocumentTooLarge = ... # type: 'QJsonParseError.ParseError'
    GarbageAtEnd = ... # type: 'QJsonParseError.ParseError'

    error = ... # type: 'QJsonParseError.ParseError'
    offset = ... # type: int

    @typing.overload
    def __init__(self) -> None: ...
    @typing.overload
    def __init__(self, a0: 'QJsonParseError') -> None: ...

    def errorString(self) -> str: ...

import

from PyQt5.QtCore import QMetaType
from PyQt5.QtCore import QJsonDocument
from PyQt5.QtCore import QJsonValue
from PyQt5.QtCore import QJsonParseError
from PyQt5.QtCore import QMetaObject
from PyQt5.QtCore import QByteArray
from PyQt5.QtCore import QFile
from PyQt5.QtCore import QFileDevice

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原始发表：2020-09-21，如有侵权请联系 cloudcommunity@tencent.com 删除

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