Defining the Data Structure

First, define the C structure that corresponds to the JSON object and the descriptor that maps the structure fields to JSON tokens.

.. code-block:: c

#include <zephyr/data/json.h>

struct foo { int bar; const char *baz; };

static const struct json_obj_descr foo_descr[] = { JSON_OBJ_DESCR_PRIM(struct foo, bar, JSON_TOK_NUMBER), JSON_OBJ_DESCR_PRIM(struct foo, baz, JSON_TOK_STRING), };

Encoding

To encode a C structure into a JSON string, use :c:func:json_obj_encode_buf.

.. code-block:: c

void encode_example(void) { struct foo data = { .bar = 42, .baz = "hello" }; char buffer[128]; int ret;

   ret = json_obj_encode_buf(foo_descr, ARRAY_SIZE(foo_descr),
                             &data,
                             buffer, sizeof(buffer));
   if (ret < 0) {
       /* handle error */
   }

}

Decoding

To decode a JSON string into a C structure, use :c:func:json_obj_parse.

.. code-block:: c

void decode_example(void) { struct foo data; const char *json_text = "{"bar": 42, "baz": "hello"}"; int ret;

   ret = json_obj_parse(json_text, strlen(json_text),
                        foo_descr, ARRAY_SIZE(foo_descr),
                        &data);
   if (ret < 0) {
       /* handle error */
   }

}

Configuration

To enable JSON support, enable the :kconfig:option:CONFIG_JSON_LIBRARY Kconfig option.

API Reference

.. doxygengroup:: json