esp-idf-json

Example of JSON Serialize and Deserialize with ESP-IDF.

ESP-IDF includes this cJSON library.
You can use JSON components as standard.
But the documentation is very poor.
The official documentation for the JSON component is here.

Here is a example by Dave Gamble.

How to use

git clone https://github.com/nopnop2002/esp-idf-json
cd esp-idf-json/json-basic-object
idf.py flash monitor

About cJSON_Print

From print_value() function, the pointer returned is allocated by cJSON_strdup() and it is returned to the caller.
Buffers returned by cJSON_Print must be freed by the caller.
Please use the proper API (cJSON_free) rather than directly calling stdlib free.

char *my_json_string = cJSON_Print(root);
ESP_LOGI(TAG, "my_json_string\n%s",my_json_string);
cJSON_Delete(root);
cJSON_free(my_json_string);

Basic Structure

• Array
  Array, like this, have no name.
  Array starts with [ and ends with ].
  root is defined by cJSON_CreateArray.
  element is added by cJSON_AddItemToArray.

["abc", 123, true, false, null]

• Object
  Object, like this, have name.
  Object starts with { and ends with }.
  root is defined by cJSON_CreateObject.
  element is added by cJSON_AddItemToObject.

{
        "version":      "v5.0-dev-3202-ga2d5041492-dirty",
        "cores":        2,
}

Complex structure

• Object in Array

["abc", 123, true, false, null, {
                "version":      "v5.0-dev-3202-ga2d5041492-dirty",
                "cores":        2
        }]

[{
                "id":   0,
                "version":      "v5.0-dev-3202-ga2d5041492-dirty",
                "cores":        2
        }, {
                "id":   1,
                "version":      "v5.0-dev-3202-ga2d5041492-dirty",
                "cores":        2
        }]

• Array in Array

[["abc", 120], ["abc", 121], ["abc", 122], ["abc", 123], ["abc", 124], ["abc", 125], ["abc", 126], ["abc", 127], ["abc", 128], ["abc", 129]]

• Object in Object

{
        "name": "Jack (\"Bee\") Nimble",
        "format":       {
                "type": "rect",
                "width":        1920,
                "height":       1080,
                "interlace":    false,
                "frame rate":   24
        }
}

• Array in Object

{
        "version":      "v5.0-dev-3202-ga2d5041492-dirty",
        "cores":        2,
        "array":        ["abc", 123, true, false, null]
}

More Complex structure

• Object in Array in Object

{
        "version":      "v5.0-dev-3202-ga2d5041492-dirty",
        "cores":        2,
        "array":  [{
                        "width":        1280,
                        "height":       720
                }, {
                        "width":        1920,
                        "height":       1080
                }, {
                        "width":        3840,
                        "height":       2160
                }]
}

• Array in Object in Array

[{
                "id":   0,
                "version":      "v5.0-dev-3202-ga2d5041492-dirty",
                "cores":        2,
                "array":        ["abc", 123, true, false, null]
        }, {
                "id":   1,
                "version":      "v5.0-dev-3202-ga2d5041492-dirty",
                "cores":        2,
                "array":        ["abc", 123, true, false, null]
        }]