Add commas after each value in PHP Array

I am trying to store every competition id in the following function:

function getSoccerByCountry($appKey, $sessionToken, $country, $competitionid)
{
    $jsonResponse = sportsApingRequest($appKey, $sessionToken, 'listMarketCatalogue', '{"filter":{
                "eventTypeIds": [
                    "1"
                ],"competitionIds":["' . $competitionid . '"],"marketTypeCodes":["MATCH_ODDS"],"marketCountries":["' . $country . '"],"inPlayOnly": true
            },
            "maxResults": "200",
            "marketProjection": [
                "COMPETITION",
                "EVENT",
                "EVENT_TYPE",
                "RUNNER_DESCRIPTION",
                "RUNNER_METADATA",
                "MARKET_START_TIME"
            ]
        },
        "id": 1}
]');

I have created this for each loop which loops every key value of the array and gets only the competition id which is being passed to the getSoccerByCountry function.

foreach ($getSoccerComp as $key1)
{           
    $getSoccerCountry = getSoccerByCountry($appKey, $sessionToken, $countrycode, $key1->competition->id);
}

Although, all the competition ids are passing as a whole integer, I want them to pass separated with a comma.

Screenshot

Something like this?

foreach ($getSoccerComp as $key1){           
    $ids[] = $key1->competition->id;
}

getSoccerByCountry($appKey, $sessionToken, $countrycode, implode(',', $ids));

Sinse you weren't doing anything with $getSoccerCountry except rewriting the variable over and over again with value null I removed the obselete code.