static const httpd_uri_t valueHandler = { .uri = "/api/value", .method = HTTP_GET, .handler = [](httpd_req_t *req) { httpd_resp_set_type(req, "application/json"); // create json docuemnt DynamicJsonDocument json(1024); json["value"] = 1.0; // Serialize JSON to string std::string buf; serializeJson(json, buf); // Send response httpd_resp_send(req, buf.c_str(), buf.length()); return ESP_OK; } };