How can I get the number of associated contents for each option?

Set ext_config_flg to true in the TopicsGroup::details endpoint and enter the extension item number of the selection type such as single choice you want to count in ext_no_for_count.

Configuration

Confugure the following parameters in the basic settings section of the endpoint configuration screen.

Example JSON Response

It will be added with the count field for the specified extension number.

{
  "errors": [],
  "messages": [],
  "details": {
    ・
    ・
    ・
  },
  "ext_config": [
    {
      "no": "1",
      "ext_col_nm": "ext_1",
      "ext_index": 1,
     ・
     ・
     ・
      "default_value": "",
      "count": {
        "1": 2,
        "2": 5,
        "3": 1,
        "4": 4
      }
    }
  ]
}