On Form Key-Value Extended

Called by the µC/HTTP-client core when the form table is formatted to be sent.

Each HTTPc_KEY_VAL_EXT objects contained in a table form must have set up a hook function pointer with the parameter OnValTx. The HTTPc transmit buffer pointer and the length available inside are passed as argument to allow the hook function to copy the data value directly inside the HTTPc buffer.

Prototype

CPU_BOOLEAN  HTTPc_FormKeyValExtHook (HTTPc_CONN_OBJ     *p_conn_obj,
                                      HTTPc_REQ_OBJ      *p_req_obj,
                                      HTTPc_KEY_VAL_EXT  *p_key_val_obj,
                                      CPU_CHAR           *p_buf,
                                      CPU_INT16U          buf_len,
                                      CPU_INT16U         *p_len_wr);

Arguments

p_conn_obj

Pointer to the current HTTPc Connection Object.

p_req_obj

Pointer to the current HTTPc Request Object.

p_key_val_obj

Pointer to the Key-Value Extended object.

p_buf

Pointer to transmit buffer.

buf_len

Length available inside the transmit buffer.

p_len_wr

Data length actually written inside the buffer by the hook function.

Return Values

DEF_YES, if all the data have been written to the buffer.

DEF_NO, otherwise

Required Configuration

None.

Notes / Warnings

None.

Example Template

Listing - HTTP Connection Hook Function that Handles External Key-Value Pairs

CPU_CHAR  HTTPc_AppBuf[512];

static  CPU_BOOLEAN  HTTPc_FormKeyValExtHook (HTTPc_CONN_OBJ     *p_conn_obj,
                                              HTTPc_REQ_OBJ      *p_req_obj,
                                              HTTPc_KEY_VAL_EXT  *p_key_val_obj,
                                              CPU_CHAR           *p_buf,
                                              CPU_INT16U          buf_len,
                                              CPU_INT16U         *p_len_wr);
{
            HTTPc_KEY_VAL_EXT  *p_field;
            CPU_CHAR           *p_data;
            CPU_INT16U          min_len;
    static  CPU_INT16U          data_ix;

    p_data = &HTTPc_AppBuf[data_ix];

    min_len = DEF_MIN(buf_len, (p_key_val_obj->ValLen - data_ix));
    if (min_len <= 0) {
        data_ix = 0;
       *p_len_wr = min_len;
        return (DEF_YES);
    }

    Str_Copy_N(p_buf, p_data, min_len);
   *p_len_wr  = min_len;
    data_ix  += min_len;

    return (DEF_NO);
}

This code uses a variable declared as static for example purpose. It cannot work if multiple connections call the same hook function. In that case, the UserDataPtr parameter inside the HTTPc_REQ_OBJ or HTTPc_CONN_OBJ can be used to store data for the application usage.