I can't parse a JSON file when the nested structure is an array

[RicardoCarvalho]

sdk 2.1.0

nRF9160

Hi,

I need to parse a JSON file and for that I'm trying to use zephyr's json.h library.

Based on the automatic test file I built a piece of code for this task, but it is not working when the nested structure is an array...

Let me explain my tests:
1-when the nested structure is not declared as an array everything works as expected

struct test_nested {
    int nested_int;
    const char *nested_string[10];
    size_t nested_string_len;
};

struct test_struct {
    struct test_nested nested_obj_array;
    int some_int;
};

static const struct json_obj_descr nested_descr[] = {
    JSON_OBJ_DESCR_PRIM(struct test_nested, nested_int, JSON_TOK_NUMBER),
    JSON_OBJ_DESCR_ARRAY(struct test_nested, nested_string, 10, nested_string_len, JSON_TOK_STRING),
};

static const struct json_obj_descr test_descr[] = {
    JSON_OBJ_DESCR_OBJECT(struct test_struct, nested_obj_array, nested_descr),
    JSON_OBJ_DESCR_PRIM(struct test_struct, some_int, JSON_TOK_NUMBER),
};

struct test_struct test2;
    char encoded2[] = "{\"nested_obj_array\":"
                      "{\"nested_int\":22,"
                      "\"nested_string\":[\"string11\",\"string12\",\"string13\",\"string14\"]},"
                      "\"some_int\":123"
                      "}";
    LOG_DBG("encoded:%s", encoded2);
    const struct test_struct expected2 = {
        .nested_obj_array = {.nested_int = 22, .nested_string = {"string11", "string12", "string13", "string14"}, .nested_string_len = 4},
        .some_int = 123,
    };
    int ret;

    ret = json_obj_parse(encoded2, sizeof(encoded2) - 1, test_descr,
                         ARRAY_SIZE(test_descr), &test2);

    if (ret != (1 << ARRAY_SIZE(test_descr)) - 1) {
        LOG_DBG("Not all fields decoded correctly! ret:%d != size:%d", ret, (1 << ARRAY_SIZE(test_descr)) - 1);
    }
    if (test2.some_int != expected2.some_int) {
        LOG_DBG("some_int not decoded correctly.");
    }
    LOG_DBG("test2.some_int=%d", test2.some_int);
    if (test2.nested_obj_array.nested_string_len != expected2.nested_obj_array.nested_string_len) {
        LOG_DBG("Number of nested_string fields not decoded correctly. decode:%d, expected:%d", test2.nested_obj_array.nested_string_len, expected2.nested_obj_array.nested_string_len);
    }
    LOG_DBG("test2.nested_obj_array.nested_string_len=%d", test2.nested_obj_array.nested_string_len);

    for (int i = 0; i < expected2.nested_obj_array.nested_string_len; i++) {
        if (0 != strcmp(test2.nested_obj_array.nested_string[i], expected2.nested_obj_array.nested_string[i])) {
            LOG_DBG("test2.nested_obj_array.nested_string[%d] not decoded correctly", i);
        }
        LOG_DBG("test2.nested_obj_array.nested_string[%d]=%s", i, test2.nested_obj_array.nested_string[i]);
    }
    if (test2.nested_obj_array.nested_int != expected2.nested_obj_array.nested_int) {
        LOG_DBG("nested_int not decoded correctly.");
    }
    LOG_DBG("test2.nested_obj_array.nested_int=%d", test2.nested_obj_array.nested_int);

output:

[00:00:28.371,063] <dbg> encoded:{"nested_obj_array":{"nested_int":22,"nested_string":["string11","string12","string13","string14"]},"some_int":123}
[00:00:28.372,039] <dbg> test2.some_int=123
[00:00:28.372,589] <dbg> test2.nested_obj_array.nested_string_len=4
[00:00:28.373,229] <dbg> test2.nested_obj_array.nested_string[0]=string11
[00:00:28.373,901] <dbg> test2.nested_obj_array.nested_string[1]=string12
[00:00:28.374,542] <dbg> test2.nested_obj_array.nested_string[2]=string13
[00:00:28.375,213] <dbg> test2.nested_obj_array.nested_string[3]=string14
[00:00:28.375,854] <dbg> test2.nested_obj_array.nested_int=22

2-when the nested structure is declared as an array but only contains one argument, it also works

struct test_nested {
    int nested_int;
    const char *nested_string[10];
    size_t nested_string_len;
};

struct test_struct {
    struct test_nested nested_obj_array[5];
    size_t nested_obj_array_len;
    int some_int;
};

static const struct json_obj_descr nested_descr[] = {
    JSON_OBJ_DESCR_PRIM(struct test_nested, nested_int, JSON_TOK_NUMBER),
    JSON_OBJ_DESCR_ARRAY(struct test_nested, nested_string, 10, nested_string_len, JSON_TOK_STRING),
};

static const struct json_obj_descr test_descr[] = {
    JSON_OBJ_DESCR_OBJ_ARRAY(struct test_struct, nested_obj_array, 5, nested_obj_array_len,
                             nested_descr, ARRAY_SIZE(nested_descr)),
    // JSON_OBJ_DESCR_OBJECT(struct test_struct, nested_obj_array, nested_descr),
    JSON_OBJ_DESCR_PRIM(struct test_struct, some_int, JSON_TOK_NUMBER),
};

struct test_struct test3;
    char encoded3[] = "{\"nested_obj_array\":["
                      "{\"nested_int\":22,"
                      "\"nested_string\":[\"string11\",\"string12\",\"string13\",\"string14\"]}"
                      "],"
                      "\"some_int\":123"
                      "}";
    LOG_DBG("encoded:%s", encoded3);
    const struct test_struct expected3 = {
        .nested_obj_array = {[0] = {.nested_int = 22, .nested_string = {"string11", "string12", "string13", "string14"}, .nested_string_len = 4}
                             },
        .some_int = 123,
        .nested_obj_array_len = 1,
    };
    int ret;

    ret = json_obj_parse(encoded3, sizeof(encoded3) - 1, test_descr,
                         ARRAY_SIZE(test_descr), &test3);

    if (ret != (1 << ARRAY_SIZE(test_descr)) - 1) {
        LOG_DBG("Not all fields decoded correctly! ret:%d != size:%d", ret, (1 << ARRAY_SIZE(test_descr)) - 1);
    }
    if (test3.some_int != expected3.some_int) {
        LOG_DBG("some_int not decoded correctly.");
    }
    LOG_DBG("test3.some_int=%d", test3.some_int);
    if (test3.nested_obj_array_len != expected3.nested_obj_array_len) {
        LOG_DBG("Number of nested_obj_array_len fields not decoded correctly. decode:%d, expected:%d", test3.nested_obj_array_len, expected3.nested_obj_array_len);
    }
    LOG_DBG("test3.nested_obj_array_len=%d", test3.nested_obj_array_len);
    for (size_t j = 0; j < expected3.nested_obj_array_len; j++) {
        if (test3.nested_obj_array[j].nested_string_len != expected3.nested_obj_array[j].nested_string_len) {
            LOG_DBG("Number of nested_obj_array[%d].nested_string_len fields not decoded correctly. decode:%d, expected:%d", j, test3.nested_obj_array[j].nested_string_len, expected3.nested_obj_array[j].nested_string_len);
        }
        LOG_DBG("test3.nested_obj_array[%d].nested_string_len=%d", j, test3.nested_obj_array[j].nested_string_len);
        
        for (int i = 0; i < expected3.nested_obj_array[j].nested_string_len; i++) {
            if (0 != strcmp(test3.nested_obj_array[j].nested_string[i], expected3.nested_obj_array[j].nested_string[i])) {
                LOG_DBG("nested_obj_array[%d].nested_string[%d] not decoded correctly", j, i);
            }
            LOG_DBG("test3.nested_obj_array[%d].nested_string[%d]=%s", j, i, test3.nested_obj_array[j].nested_string[i]);
        }
        if (test3.nested_obj_array[j].nested_int != expected3.nested_obj_array[j].nested_int) {
                LOG_DBG("nested_int not decoded correctly.");
            }
        LOG_DBG("test3.nested_obj_array[%d].nested_int=%d", j, test3.nested_obj_array[j].nested_int);
    }

output:

[00:01:30.089,050] <dbg> encoded:{"nested_obj_array":[{"nested_int":22,"nested_string":["string11","string12","string13","string14"]}],"some_int":123}
[00:01:30.090,057] <dbg> test3.some_int=123
[00:01:30.090,606] <dbg> test3.nested_obj_array_len=1
[00:01:30.091,217] <dbg> test3.nested_obj_array[0].nested_string_len=4
[00:01:30.091,857] <dbg> test3.nested_obj_array[0].nested_string[0]=string11
[00:01:30.092,529] <dbg> test3.nested_obj_array[0].nested_string[1]=string12
[00:01:30.093,200] <dbg> test3.nested_obj_array[0].nested_string[2]=string13
[00:01:30.093,902] <dbg> test3.nested_obj_array[0].nested_string[3]=string14
[00:01:30.094,573] <dbg> test3.nested_obj_array[0].nested_int=22

3-when the nested structure is declared as an array but contains several arguments it does not parse correctly...

struct test_nested {
    int nested_int;
    const char *nested_string[10];
    size_t nested_string_len;
};

struct test_struct {
    struct test_nested nested_obj_array[5];
    size_t nested_obj_array_len;
    int some_int;
};

static const struct json_obj_descr nested_descr[] = {
    JSON_OBJ_DESCR_PRIM(struct test_nested, nested_int, JSON_TOK_NUMBER),
    JSON_OBJ_DESCR_ARRAY(struct test_nested, nested_string, 10, nested_string_len, JSON_TOK_STRING),
};

static const struct json_obj_descr test_descr[] = {
    JSON_OBJ_DESCR_OBJ_ARRAY(struct test_struct, nested_obj_array, 5, nested_obj_array_len,
                             nested_descr, ARRAY_SIZE(nested_descr)),
    // JSON_OBJ_DESCR_OBJECT(struct test_struct, nested_obj_array, nested_descr),
    JSON_OBJ_DESCR_PRIM(struct test_struct, some_int, JSON_TOK_NUMBER),
};

struct test_struct test3;
    char encoded3[] = "{\"nested_obj_array\":["
                      "{\"nested_int\":22,"
                      "\"nested_string\":[\"string11\",\"string12\",\"string13\",\"string14\"]},"
                      "{\"nested_int\":33,"
                      "\"nested_string\":[\"string21\",\"string22\",\"string23\",\"string24\"]}"
                      "],"
                      "\"some_int\":123"
                      "}";
    LOG_DBG("encoded:%s", encoded3);
    const struct test_struct expected3 = {
        .nested_obj_array = {[0] = {.nested_int = 22, .nested_string = {"string11", "string12", "string13", "string14"}, .nested_string_len = 4},
                             [1] = {.nested_int = 33, .nested_string = {"string21", "string22", "string23", "string24"}, .nested_string_len = 4}
                             },
        .some_int = 123,
        .nested_obj_array_len = 2,
    };
    int ret;

    ret = json_obj_parse(encoded3, sizeof(encoded3) - 1, test_descr,
                         ARRAY_SIZE(test_descr), &test3);

    if (ret != (1 << ARRAY_SIZE(test_descr)) - 1) {
        LOG_DBG("Not all fields decoded correctly! ret:%d != size:%d", ret, (1 << ARRAY_SIZE(test_descr)) - 1);
    }
    if (test3.some_int != expected3.some_int) {
        LOG_DBG("some_int not decoded correctly.");
    }
    LOG_DBG("test3.some_int=%d", test3.some_int);
    if (test3.nested_obj_array_len != expected3.nested_obj_array_len) {
        LOG_DBG("Number of nested_obj_array_len fields not decoded correctly. decode:%d, expected:%d", test3.nested_obj_array_len, expected3.nested_obj_array_len);
    }
    LOG_DBG("test3.nested_obj_array_len=%d", test3.nested_obj_array_len);
    for (size_t j = 0; j < expected3.nested_obj_array_len; j++) {
        if (test3.nested_obj_array[j].nested_string_len != expected3.nested_obj_array[j].nested_string_len) {
            LOG_DBG("Number of nested_obj_array[%d].nested_string_len fields not decoded correctly. decode:%d, expected:%d", j, test3.nested_obj_array[j].nested_string_len, expected3.nested_obj_array[j].nested_string_len);
        }
        LOG_DBG("test3.nested_obj_array[%d].nested_string_len=%d", j, test3.nested_obj_array[j].nested_string_len);
        
        for (int i = 0; i < expected3.nested_obj_array[j].nested_string_len; i++) {
            if (0 != strcmp(test3.nested_obj_array[j].nested_string[i], expected3.nested_obj_array[j].nested_string[i])) {
                LOG_DBG("nested_obj_array[%d].nested_string[%d] not decoded correctly", j, i);
            }
            LOG_DBG("test3.nested_obj_array[%d].nested_string[%d]=%s", j, i, test3.nested_obj_array[j].nested_string[i]);
        }
        if (test3.nested_obj_array[j].nested_int != expected3.nested_obj_array[j].nested_int) {
                LOG_DBG("nested_int not decoded correctly.");
            }
        LOG_DBG("test3.nested_obj_array[%d].nested_int=%d", j, test3.nested_obj_array[j].nested_int);
    }

output:

[00:00:55.869,873] <dbg> encoded:{"nested_obj_array":[{"nested_int":22,"nested_string":["string11","string12","string13","string14"]},{"nested_int":33,"nested_string":["string21","string22","string23","string24"]}],"some_int":123}
[00:00:55.871,215] <dbg> test3.some_int=123
[00:00:55.871,765] <dbg> test3.nested_obj_array_len=2
[00:00:55.872,375] <dbg> Number of nested_obj_array[0].nested_string_len fields not decoded correctly. decode:33, expected:4
[00:00:55.873,168] <dbg> test3.nested_obj_array[0].nested_string_len=33
[00:00:55.873,840] <dbg> test3.nested_obj_array[0].nested_string[0]=string11
[00:00:55.874,542] <dbg> test3.nested_obj_array[0].nested_string[1]=string12
[00:00:55.875,213] <dbg> test3.nested_obj_array[0].nested_string[2]=string13
[00:00:55.875,915] <dbg> test3.nested_obj_array[0].nested_string[3]=string14
[00:00:55.876,586] <dbg> test3.nested_obj_array[0].nested_int=22
[00:00:55.877,227] <dbg> Number of nested_obj_array[1].nested_string_len fields not decoded correctly. decode:243463, expected:4
[00:00:55.878,051] <dbg> test3.nested_obj_array[1].nested_string_len=243463
[00:00:55.878,753] <dbg> nested_obj_array[1].nested_string[0] not decoded correctly
[00:00:55.879,425] <dbg> test3.nested_obj_array[1].nested_string[0]=string22
[00:00:55.880,126] <dbg> nested_obj_array[1].nested_string[1] not decoded correctly
[00:00:55.880,798] <dbg> test3.nested_obj_array[1].nested_string[1]=string23
[00:00:55.881,500] <dbg> nested_obj_array[1].nested_string[2] not decoded correctly
[00:00:55.882,171] <dbg> test3.nested_obj_array[1].nested_string[2]=string24
[00:00:55.882,873] <dbg> nested_obj_array[1].nested_string[3] not decoded correctly
[00:00:55.883,544] <dbg> test3.nested_obj_array[1].nested_string[3]=
[00:00:55.884,216] <dbg> nested_int not decoded correctly.
[00:00:55.884,796] <dbg> test3.nested_obj_array[1].nested_int=537041920

What am I doing wrong?
Can you tell me how I can do this?

The final objective is to be able to parse a JSON with the following format:

{
  "nested_obj": [
    {
      "nested_int": 123,
      "nested_int2": 45,
      "nested_nested_obj": {
        "nested_nested_array": [
          "array1",
          "array2",
          "array3",
          "..."
        ]
      }
    },
    {
      "nested_int": 678,
      "nested_int2": 90,
      "nested_nested_obj": {
        "nested_nested_array": [
          "array1",
          "array2",
          "array3",
          "..."
        ]
      }
    }
  ],
  "some_string": "string"
}

Thanks!
Regards,
Ricardo

[Hakon]

Hello,

this question does not seem related to Nordic specifically, but rather Zephyr in general. Is this behavior happening just on Nordic equipment? If not, I believe you should ask the Zephyr community instead.

[RicardoCarvalho]

Hi Hakon,

I don't know if this problem is only with Nordic equipment, I don't have another brand to test the Zephyr on...

Can you tell me where in the zephyr community is the most appropriate place for me to ask this question?

Thanks for the help.

Regards,
Ricardo

[RicardoCarvalho]

Hi,

I managed to solve this problem using the json.c and json.h files from SDK version 2.6.1.

Apparently this bug was fixed as of version 3.4 of zephyr (SDK 2.5.0)

Regards,

Ricardo