Function to create a Database and query whether it exits or not

[caspianron]

Hi,
Thank you very much for your for solving my previous issue. I have a question 👍
Which function to call from .hpp file to ""create a Database and query whether it exits or not"".?

Thanks
Raunak

[orca-zhang]

Hi,

Good day.

I've added a method influxdb_cpp::create_db to support creating a database according to the offical document.

You can refer to demo file for more details.

And query whether it exists or not, the best practice I think is below:

    string resp;
    influxdb_cpp::server_info si("127.0.0.1", 8086, "", "test" /* usr */, "test" /* passwd */);
    int ret = influxdb_cpp::query(resp, "show databases", si);
    // check error code
    // assert(ret == 0);

Then check the db list in the resp, the json response is like below.

{
	"results": [{
		"series": [{
			"name": "databases",
			"columns": ["name"],
			"values": [
				["_internal"],
				["test"],
				["test1"],
				["x"]
			]
		}]
	}]
}

Using xpjson:

#include <xpjson.hpp>

bool check_db_exists(const string& resp, const string& db_name)
    JSON::Value v;
    v.read(resp);
    JSON::Array& a = v["results"][0]["series"][0]["values"].a();
    for(size_t i = 0; i < a.size(); ++i) {
        if(a[i][0] == db_name) {
            return true;
        }
    }
    return false;
}

You should only check the error code of influxdb::query, don't worry if the response is empty or error occurred, the result is always OK.

Thank you for your feedback.

Orca

[caspianron]

Thanks a lot