BigQuery - Fetch table data from Go Server in Cloud Run - go

Question

I am able to fetch the Big Query table output as json through Golang server. But is there a way to fetch the schema directly instead of defining it as ColStatsRow? Also, any way to make this better.
type ColStatsRow struct {
COLUMN_NAME string `bigquery:"column_name"`
COLUMN_VALUE string `bigquery:"column_value"`
FREQUENCY int64 `bigquery:"frequency"`
}
// getOutput prints results from a query
func getOutput(w http.ResponseWriter, iter *bigquery.RowIterator) error {
var rows []ColStatsRow
for {
var row ColStatsRow
err := iter.Next(&row)
if err == iterator.Done {
out, err := json.Marshal(rows)
if err != nil {
return fmt.Errorf("error marshalling results: %v", err)
}
w.Write([]byte(out))
return nil
}
if err != nil {
return fmt.Errorf("error iterating through results: %v", err)
}
rows = append(rows, row)
}
}
Thank you.

Answer 1

If you're after the schema for the result, it's available on the RowIterator.
If you mean you want to more dynamically process the rows without a specific struct, usually some combination of checking the schema and/or leveraging a type switch is the way to go about this.

Answer 2

According to the documentation you can specify a JSON schema file like this:
[
{
"description": "[DESCRIPTION]",
"name": "[NAME]",
"type": "[TYPE]",
"mode": "[MODE]"
},
{
"description": "[DESCRIPTION]",
"name": "[NAME]",
"type": "[TYPE]",
"mode": "[MODE]"
}
]
and then you can write this schema using the following command:
bq show --schema --format=prettyjson project_id:dataset.table > path_to_file