结构体数组如何序列化？ about struct2json

[armink]

这个功能现在确实还不支持。你有没有比较好的办法呢？

[zlr3538]

我这几天绞尽脑汁，勉励改出了一个可以支持的样子，但是却完全失去了原有的样子，不仅有了start和end，而且参数的数量和位置也不再统一。
我觉得你这个封装的设计目的应该是，希望用简洁的格式，描述struct和json之间的转换关系。这也是为什么你的封装看起来不像是过程而像是一种声明。
我想到的一个办法，就是用一些声明语句，构造一个树来描述struct，那么这个如果这树和json解析的树相同，就可以用遍历的方法将他们两者进行转化。这样应该能保持简洁的描述，也可以处理json中各种情况，一次描述应该就可以实现两个方向的互转。毕竟C没有元信息，结构体和其中变量的描述，肯定要通过额外的方法再声明一遍。你看这个思路是不是可行？

[armink]

树的方案是可行的，就是工作量会非常大。

start 和 end 的那个方案改完是什么样子？

[zlr3538]

大概是这样,可以说非常丑陋了，而且弄得很复杂，感觉也不是很靠谱

typedef struct {
    char name[16];
} Hometown;

typedef struct {
    int ranking;
    int score;
} Results;

typedef struct {
    int id;
    double weight;
    char name[10];
    int attendance [10];
    Hometown hometown;
    Results results[5];
} Student;

/**
 * Student JSON object to structure object
 *
 * @param json_obj JSON object
 *
 * @return structure object
 */
static void *json_to_struct(json_object* json_obj) {
    /* create Student structure object */
    s2j_create_struct_obj(struct_student, Student);

    /* deserialize data to Student structure object. */
    s2j_struct_get_basic_element(struct_student, json_obj, int, id);
    s2j_struct_get_basic_element(struct_student, json_obj, double, weight);
    s2j_struct_get_basic_element(struct_student, json_obj, string, name);
    

    {
        s2j_struct_get_struct_element_start(struct_student, json_obj, int, attendance);
        s2j_struct_get_array_element_start(CHILD_STRUCT,CHILD_ELEMENT,int);
        s2j_struct_get_array_basic_element(ARRAY_STRUCT, ARRAY_ELEMENT, int, attendance);
        s2j_struct_get_array_element_end();
        s2j_struct_get_struct_element_end();
    }
    
    {
    /* deserialize data to Student.Hometown structure object. */
        s2j_struct_get_struct_element_start(struct_student, json_obj, Hometown, hometown);
        s2j_struct_get_basic_element(CHILD_STRUCT, CHILD_ELEMENT, string, name);
        s2j_struct_get_struct_element_end();
    }

    {
        s2j_struct_get_struct_element_start(struct_student, json_obj, Results, results);
        s2j_struct_get_array_element_start(CHILD_STRUCT,CHILD_ELEMENT,Results);        
        s2j_struct_get_basic_element(ARRAY_STRUCT, ARRAY_ELEMENT, int ,ranking);
        s2j_struct_get_basic_element(ARRAY_STRUCT, ARRAY_ELEMENT, int ,score);
        s2j_struct_get_array_element_end();
        s2j_struct_get_struct_element_end();
    }
    
    /* return Student structure object pointer */
    return struct_student;
}

/**
 * Student structure object to JSON object
 *
 * @param struct_obj structure object
 *
 * @param JSON object
 */
static json_object *struct_to_json(void* struct_obj) {
    Student *struct_student = (Student *)struct_obj;

    /* create Student JSON object */
    s2j_create_json_obj(json_student);

    /* serialize data to Student JSON object. */
    s2j_json_set_basic_element(json_student, struct_student, int, id);
    s2j_json_set_basic_element(json_student, struct_student, double, weight);
    s2j_json_set_basic_element(json_student, struct_student, string, name);

    {
        s2j_json_set_array_element_start(json_student, int, 10);
        s2j_json_set_array_basic_element(ARRAY_ELEMENT, struct_student, int, attendance);
        s2j_json_set_array_element_end(json_student, attendance);
    }

    {
        /* serialize data to Student.Hometown JSON object. */
        s2j_json_set_struct_element_start(struct_student, Hometown, hometown);
        s2j_json_set_basic_element(CHILD_ELEMENT, CHILD_STRUCT, string, name);
        s2j_json_set_struct_element_end(json_student, hometown);
    }

    {
        s2j_json_set_array_element_start(json_student, Results, 5);
        s2j_json_set_array_struct_element_start(struct_student, Results, results);
        s2j_json_set_basic_element(CHILD_ELEMENT, CHILD_STRUCT, int, ranking);
        s2j_json_set_basic_element(CHILD_ELEMENT, CHILD_STRUCT, int, score);
        s2j_json_set_struct_element_end(ARRAY_ELEMENT, results);
        s2j_json_set_array_element_end(json_student, results);
    }
    /* return Student JSON object pointer */
    return json_student;
}

[armink]

可以把 s2j_struct_get_struct_element_start 与 s2j_struct_get_array_element_start ，以及对应的 end 合并为一个吗？

例如：s2j_struct_get_struct_array_element_start

[zlr3538]

我把他们拆成两个纯粹无奈之举，展开来其实是一个循环，在循环里面遍历struct
展开是下面这个样子，我这个因为需要把cjson换成json-c，其他一样的

#define S2J_STRUCT_GET_ARRAY_ELEMENT_START(to_struct, from_json, type) \
    { \
        struct json_object *array, *array_element; \
        size_t index = 0, size = 0; \
        array = from_json; \
        if (array) { \
            size = json_object_array_length(array); \
            while (index < size) { \
                array_element = json_object_array_get_idx(array, index); \
                if (array_element) { \
                    type *array_struct = &(((type*)(to_struct))[index]);
                    

#define S2J_STRUCT_GET_ARRAY_ELEMENT_END() \
                index++; } \
            } \
        } \
     }

#define S2J_STRUCT_GET_STRUCT_ELEMENT_START(to_struct, from_json, type, _element) \
    { \
        type *child_struct = &((to_struct)->_element); \
        struct json_object *child_element = json_object_object_get(from_json, #_element); \
        if(child_element) {

#define S2J_STRUCT_GET_STRUCT_ELEMENT_END() \
        } \
    }

[EveryDayNew]

以下的这个结构体数组，能否转化为json，如果能那种方法比较合适
typedef struct KR {
char name[50];
char evaluation[400];
float weight;
char completion[20];
float score;
} kr;

typedef struct objective {
char name[50];
kr KRs[3];
float score;
} obj;

typedef struct OKR {
char name[50];
float totalPoints;
float weight[2];
obj objs[2];
} okr;

okr okrs[12];

[yuxuebao]

参考下面的分支，已经实现结构体和数组的转换，并提供自动生成转换代码的脚本：）
https://github.com/yuxuebao/struct2json

[yuxuebao]

已经实现，自动生成的转换代码示例：
#if 0
typedef struct McBaseOrdrS
{
int64 ordrNo;
int64 intrlOrdrNo;
int64 exePrc;
int64 elstcPrc;
int64 ordrQty;
int64 effectTime;
int32 ordSide;
int32 ordrType;
int32 usrSqno;
int32 prdctSqno;
int32 orgSqno;
int32 extOrdType;
int32 ordrRestr;
} McBaseOrdrT, *pMcBaseOrdrT;
#endif
cJSON struct_to_json_McBaseOrdrT(void struct_obj)
{
s2j_create_json_obj(json_obj_);
McBaseOrdrT *struct_obj_ = (McBaseOrdrT *)struct_obj;
s2j_json_set_basic_element(json_obj_, struct_obj_, int, ordrNo);
s2j_json_set_basic_element(json_obj_, struct_obj_, int, intrlOrdrNo);
s2j_json_set_basic_element(json_obj_, struct_obj_, int, exePrc);
s2j_json_set_basic_element(json_obj_, struct_obj_, int, elstcPrc);
s2j_json_set_basic_element(json_obj_, struct_obj_, int, ordrQty);
s2j_json_set_basic_element(json_obj_, struct_obj_, int, effectTime);
s2j_json_set_basic_element(json_obj_, struct_obj_, int, ordSide);
s2j_json_set_basic_element(json_obj_, struct_obj_, int, ordrType);
s2j_json_set_basic_element(json_obj_, struct_obj_, int, usrSqno);
s2j_json_set_basic_element(json_obj_, struct_obj_, int, prdctSqno);
s2j_json_set_basic_element(json_obj_, struct_obj_, int, orgSqno);
s2j_json_set_basic_element(json_obj_, struct_obj_, int, extOrdType);
s2j_json_set_basic_element(json_obj_, struct_obj_, int, ordrRestr);
return json_obj_;
}

void json_to_struct_McBaseOrdrT(cJSON json_obj)
{
s2j_create_struct_obj(struct_obj_, McBaseOrdrT);
s2j_struct_get_basic_element(struct_obj_,json_obj, int, ordrNo);
s2j_struct_get_basic_element(struct_obj_,json_obj, int, intrlOrdrNo);
s2j_struct_get_basic_element(struct_obj_,json_obj, int, exePrc);
s2j_struct_get_basic_element(struct_obj_,json_obj, int, elstcPrc);
s2j_struct_get_basic_element(struct_obj_,json_obj, int, ordrQty);
s2j_struct_get_basic_element(struct_obj_,json_obj, int, effectTime);
s2j_struct_get_basic_element(struct_obj_,json_obj, int, ordSide);
s2j_struct_get_basic_element(struct_obj_,json_obj, int, ordrType);
s2j_struct_get_basic_element(struct_obj_,json_obj, int, usrSqno);
s2j_struct_get_basic_element(struct_obj_,json_obj, int, prdctSqno);
s2j_struct_get_basic_element(struct_obj_,json_obj, int, orgSqno);
s2j_struct_get_basic_element(struct_obj_,json_obj, int, extOrdType);
s2j_struct_get_basic_element(struct_obj_,json_obj, int, ordrRestr);
return struct_obj_;
}

#if 0
typedef struct McBaseOrdrArray
{
McBaseOrdrT mcBaseOrdrArray[2] ;
} McBaseOrdrArrayT;
#endif
cJSON struct_to_json_McBaseOrdrArrayT(void struct_obj)
{
s2j_create_json_obj(json_obj_);
McBaseOrdrArrayT *struct_obj_ = (McBaseOrdrArrayT *)struct_obj;
s2j_json_set_struct_array_element_by_func(json_obj_, struct_obj_, McBaseOrdrT,mcBaseOrdrArray,2);
return json_obj_;
}

void json_to_struct_McBaseOrdrArrayT(cJSON json_obj)
{
s2j_create_struct_obj(struct_obj_, McBaseOrdrArrayT);
s2j_struct_get_struct_array_element_by_func(struct_obj_, json_obj, McBaseOrdrT,mcBaseOrdrArray);
return struct_obj_;
}

[armink]

参考下面的分支，已经实现结构体和数组的转换，并提供自动生成转换代码的脚本：）
https://github.com/yuxuebao/struct2json

Cool