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3rd | ||
adapter | ||
demo | ||
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Makefile | ||
README.md | ||
README_EN.md |
README_EN.md
简体中文 | English
cson
Transformation between json string and struct.
The transformation between string to JSON objects (e.g. json_t in Jansson) is implemented by a third-party library (Jansson or cJSON. Refer to Dependence). What cson really implements is the transformation between JSON object and structure.
Compilation
Compile static library
$ git clone https://github.com/sunchb/cson.git
$ cd cson
$ make
Compile demo
$ cd demo
$ make
$ ./test
How to use
- Define the data structure for JSON.
- Define the property description table for data structure.
- Call cson api to decode or encode.
Dependence
https://github.com/akheron/jansson.git https://github.com/DaveGamble/cJSON.git
Demo
Here is a JSON with various data types. eg. Interger, String, Real, Boolean, Object, and Array. We're going to decode and encode it by cson.
{
"name":"jay zhou",
"creater":"dahuaxia",
"songNum":2,
"songList":[
{
"songName":"qilixiang",
"signerName":"jay zhou",
"albumName":"qilixiang",
"url":"www.kugou.com",
"duration":200,
"paid":false,
"price":6.6600000000000001,
"lyricNum":2,
"lyric":[
{
"time":1,
"text":"Sparrow outside the window"
},
{
"time":10,
"text":"Multi mouth on the pole"
}
]
},
{
"songName":"dongfengpo",
"signerName":"jay zhou",
"albumName":"dongfengpo",
"url":"music.qq.com",
"duration":180,
"paid":true,
"price":0.88,
"lyricNum":2,
"lyric":[
{
"time":10,
"text":"A sad parting, standing alone in the window"
},
{
"time":20,
"text":"I'm behind the door pretending you're not gone"
}
]
}
],
"extData":{
"a":999,
"b":1.05
}
}
1. Define the data structure for JSON.
Even if you don't use cson, you usually need to do like this.
Attention
- String must be declared as char*.
- Array must be declared as pointer.
- Declare additional properties to hold the array size for every array property.
- The structure property name must be the same as the JSON field name.
typedef struct {
int time;
char* text; /* String must be declared as char* */
} Lyric;
typedef struct {
char* songName;
char* signerName;
char* albumName;
char* url;
int duration;
int paid;
double price;
size_t lyricNum; /* Declare additional properties to hold the array size */
Lyric* lyric; /* Array must be declared as pointer */
} SongInfo;
typedef struct {
int a;
double b;
} ExtData;
typedef struct {
char* name;
char* creater;
size_t songNum;
SongInfo* songList;
ExtData extData;
} PlayList;
2. Define the property description table for data structure.
Use following definitions to help you describe the structure.
- _property_int(type, field)
- _property_real(type, field)
- _property_bool(type, field)
- _property_string(type, field)
- _property_obj(type, field, tbl)
- _property_array_object(type, field, tbl, arrayType, countfild) # I know it's a little cumbersome, I'm trying to simplify it.
- _property_array_int(type, field, arrayType, countfild)
- _property_array_string(type, field, arrayType, countfild)
- _property_array_real(type, field, arrayType, countfild)
- _property_array_bool(type, field, arrayType, countfild)
Args notes:
- type: type of data structure
- field: property name
- tbl: description table of the property type. use when object or object array
- arrayType: type of the array (Used to calculate size when dynamically get array memory)
- countfild: property to save array size
You can also use macro definitions with extended parameters, the range of args is _ex_args_nullable, _ex_args_exclude_decode, _ex_args_exclude_encode and thire combinations.
-
#define _ex_args_nullable (0x01) //continue parse or encode when the field exception occurred. Default is "ON".
-
#define _ex_args_exclude_decode (0x02) //do not parse the field.
-
#define _ex_args_exclude_encode (0x04) //do not encode the field.
-
#define _ex_args_all (_ex_args_nullable | _ex_args_exclude_decode | _ex_args_exclude_encode)
-
_property_int_ex(type, field, args)
-
_property_real_ex(type, field, args)
-
_property_bool_ex(type, field, args)
-
_property_string_ex(type, field, args)
-
_property_obj_ex(type, field, tbl, args)
-
_property_array_ex(type, field, tbl, subType, count, args)
-
_property_array_object_ex(type, field, tbl, subType, count, args)
-
_property_array_int_ex(type, field, subType, count, args)
-
_property_array_string_ex(type, field, subType, count, args)
-
_property_array_real_ex(type, field, subType, count, args)
-
_property_array_bool_ex(type, field, subType, count, args)
/* description for Lyric */
reflect_item_t lyric_ref_tbl[] = {
_property_int(Lyric, time),
_property_string(Lyric, text),
_property_end()
};
/* description for SongInfo */
reflect_item_t song_ref_tbl[] = {
_property_string(SongInfo, songName),
_property_string(SongInfo, signerName),
_property_string(SongInfo, albumName),
_property_string(SongInfo, url),
_property_int(SongInfo, duration),
_property_bool(SongInfo, paid),
_property_real(SongInfo, price),
_property_int(SongInfo, lyricNum),
_property_array(SongInfo, lyric, lyric_ref_tbl, Lyric, lyricNum), /* Lyric: type of array; lyricNum: property to save array size */
_property_end()
};
/* description for ExtData */
reflect_item_t ext_data_ref_tbl[] = {
_property_int(ExtData, a),
_property_real(ExtData, b),
_property_end()
};
/* description for PlayList */
reflect_item_t play_list_ref_tbl[] = {
_property_string(PlayList, name),
_property_string(PlayList, creater),
_property_int(PlayList, songNum),
_property_array(PlayList, songList, song_ref_tbl, SongInfo, songNum),
_property_obj(PlayList, extData, ext_data_ref_tbl),
_property_end()
};
3. Call cson api to decode or encode.
PlayList playList;
/* Decode */
csonJsonStr2Struct(jStr, &playList, play_list_ref_tbl);
/* Encode */
char* jstrOutput;
csonStruct2JsonStr(&jstrOutput, &playList, play_list_ref_tbl);
Restrict
- Multidimensional arrays are not supported.
- Cjson is used by default. If you want to use jannson or other json lib, please modify $(JSON_LIB) in makefile.