# mco_lJSON_obj_open_obj
RT

### Prototype

        MCO_RET mco_lJSON_obj_open_obj(lews_JSON_context_h json_ctx, const char *key);

### Arguments

`json_ctx`
Pointer to an initialized `lews_JSON_context_t` structure.
`key`
Null-terminated string specifying the name of the nested object to be added to the current JSON object.

### Description

> This function adds a new nested JSON object as a member of the current JSON object, using the specified `key` as its name (e.g., `"address": { ... }`). After this call, all subsequent JSON construction operations (e.g., `mco_lJSON_obj_add_str`, `mco_lJSON_obj_add_int`) will operate on this newly opened inner object until it is closed with `mco_lJSON_obj_close()`.

> The function may trigger a buffer flush and send data over the network if there is insufficient space in the output buffer to write the key and opening brace (`"key":{`).

> This function can only be called when the current context is inside a JSON object. Attempting to call it at the root level or inside an array will result in an error.

>         ...
>         ret = mco_lJSON_obj_open_obj(&json_ctx, "address");
>         if (ret == MCO_S_OK) {
>             ret = mco_lJSON_obj_add_str(&json_ctx, "street", "Main Street");
>             if (ret != MCO_S_OK) {
>                 printf("mco_lJSON_obj_add_str error %d\n", ret);
>             }
>             ret = mco_lJSON_obj_add_str(&json_ctx, "city", "New York");
>             if (ret != MCO_S_OK) {
>                 printf("mco_lJSON_obj_add_str error %d\n", ret);
>             }
>             ret = mco_lJSON_obj_close(&json_ctx);
>             if (ret != MCO_S_OK) {
>                 printf("mco_lJSON_obj_close error %d\n", ret);
>             }
>         }
>         ...

### Return Codes

`MCO_S_OK`
Nested JSON object successfully opened and added to the current object.
`MCO_E_NW_SENDERR`
An error occurred while flushing the output buffer due to insufficient space for the key and opening brace.
`MCO_E_LEWS_JSON_STACK_OVERFLOW`
The internal JSON nesting stack has reached its maximum depth.
`MCO_E_LEWS_PARENT_IS_NOT_OBJECT`
The current parent context is not a JSON object (e.g., you are at the root level or inside an array).
Other error codes
May indicate internal errors (e.g., invalid arguments, null pointers).

### Files

Header file:
mcoewslite.h
Source file:
mcoewslite.c
Library:
mcoewslite.a