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https://github.com/qt-json/qt-json
A simple class for parsing JSON data into a QVariant hierarchy and vice versa.
https://github.com/qt-json/qt-json
json qt
Last synced: about 2 months ago
JSON representation
A simple class for parsing JSON data into a QVariant hierarchy and vice versa.
- Host: GitHub
- URL: https://github.com/qt-json/qt-json
- Owner: qt-json
- License: gpl-3.0
- Created: 2011-06-24T06:20:59.000Z (almost 13 years ago)
- Default Branch: master
- Last Pushed: 2018-02-12T12:05:04.000Z (over 6 years ago)
- Last Synced: 2024-03-22T15:12:48.073Z (3 months ago)
- Topics: json, qt
- Language: C++
- Homepage:
- Size: 79.1 KB
- Stars: 322
- Watchers: 26
- Forks: 103
- Open Issues: 7
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Lists
- awesome-cpp - qt-json - A simple class for parsing JSON data into a QVariant hierarchy and vice versa. [GPLv3] (JSON)
README
The **qt-json** project is a simple collection of functions for parsing and serializing [JSON][js] data to and from [QVariant][var]
hierarchies.
**NOTE:** Qt5 introduced [a native JSON object class][qt5]. If you are targeting Qt5, you should use that instead.
### HOW TO USE ###
#### Parsing JSON ####
The parser is really easy to use. Let's say we have the following
QString of JSON data:
```json
{
"encoding" : "UTF-8",
"plug-ins" : [
"python",
"c++",
"ruby"
],
"indent" : {
"length" : 3,
"use_space" : true
}
}
```
We would first call the parse-function:
```cpp
#include "json.h"
bool ok;
// json is a QString containing the JSON data
QtJson::JsonObject result = QtJson::parse(json, ok).toMap();
if(!ok) {
qFatal("An error occurred during parsing");
```
Assuming the parser completed without errors, we can then
go through the hierarchy:
```cpp
qDebug() << "encoding:" << result["encoding"].toString();
qDebug() << "plugins:";
foreach(QVariant plugin, result["plug-ins"].toList()) {
qDebug() << " -" << plugin.toString();
}
QtJson::JsonObject nested = result["indent"].toMap();
qDebug() << "length:" << nested["length"].toInt();
qDebug() << "use_space:" << nested["use_space"].toBool();
```
The previous code would print out the following:
encoding: "UTF-8"
plugins:
- "python"
- "c++"
- "ruby"
length: 3
use_space: true
#### Serializing JSON ####
To write JSON data from Qt object is as simple as creating and assigning data to a [QVariantMap/JsonObject][varmap]:
```cpp
QtJson::JsonObject contributor;
contributor["name"] = "Luis Gustavo";
contributor["age"] = 22;
QByteArray data = QtJson::serialize(contributor);
```
The byte array 'data' contains valid JSON data:
```json
{
"name": "Luis Gustavo",
"age": 22
}
```
#### Serializing JSON pretty-print ####
By default, the serialization will create a _minified_ version, like following:
```json
{"name":"Luis Gustavo","age":22}
```
If you are debugging or logging, you may prefer to enable **pretty-print** mode globally, before serialize:
```cpp
QtJson::setPrettySerialize(true);
QByteArray data = QtJson::serialize(contributor);
// ...
QByteArray data = QtJson::serialize(other_contributor);
```
Obviously, you can disable it with:
```cpp
QtJson::setPrettySerialize(false);
```
---
After creating the QVariantMap, you can create a [QVariantList/JsonArray][varlist] and append the QVariantMaps.
```cpp
QtJson::JsonObject friend1, friend2, friend3;
friend1["id"] = 1;
friend1["name"] = "Mackenzie Hamphrey";
friend2["id"] = 2;
friend2["name"] = "Melanie Molligan";
friend3["id"] = 3;
friend3["name"] = "Sydney Calhoun";
QtJson::JsonArray friends;
friends.append(friend1);
friends.append(friend2);
friends.append(friend3);
QtJson::JsonObject obj;
obj["friends"] = friends;
```
This way you create a nested structure:
```json
{
"friends": [
{
"id": 1,
"name": "MackenzieHamphrey"
},
{
"id": 2,
"name": "MelanieMolligan"
},
{
"id": 3,
"name": "SydneyCalhoun"
}
]
}
```
If you continue this process recursively, you nest more levels into the JSON structure.
#### Using Builders ####
For simplicity you can use **builders**, if you prefer.
For example, create a `JsonObject`:
```cpp
QtJson::JsonObject json = QtJson::objectBuilder()
->set("field_1", 10)
->set("field_2", "A string")
->set("field_3", true)
->set("field_4", QtJson::objectBuilder()
->set("sub_field_1", 10.4)
->set("sub_field_n", "Another string")
)
->create();
```
Or create a `JsonArray`:
```cpp
QtJson::JsonArray json = QtJson::arrayBuilder()
->add(5)
->add(90.2)
->add(true)
->add("anything else")
->create();
```
Take a look at this example that rewrite the previous one:
```cpp
QtJson::JsonObject obj = QtJson::objectBuilder()
->set("friends", QtJson::arrayBuilder()
->add(QtJson::objectBuilder()
->set("id", 1)
->set("name", "Mackenzie Hamphrey")
)
->add(QtJson::objectBuilder()
->set("id", 2)
->set("name", "Melanie Molligan")
)
->add(QtJson::objectBuilder()
->set("id", 3)
->set("name", "Sydney Calhoun")
)
)
->create();
```
### 3. CONTRIBUTING ###
Send in a pull request and bug the maintainer until it gets merged and published.
Make sure to add yourself to AUTHORS.
[js]: http://www.json.org/ "JSON Standard specification"
[var]: http://qt-project.org/doc/qt-4.8/qvariant.html "QVariant class reference"
[qt5]: http://qt-project.org/doc/qt-5.0/qtcore/qjsonobject.html "Qt5 QJsonObject class reference"
[varmap]: http://qt-project.org/doc/qt-4.8/qvariant.html#QVariantMap-typedef "Qt4 QVariantMap class reference"
[varlist]: http://qt-project.org/doc/qt-4.8/qvariant.html#QVariantList-typedef "Qt4 QVariantList class reference"