Is there a way to get the Type for a Column using package database/sql in golang? - sql

Question

Basically, without knowing before hand what the resulting structure of a query might be, I'd like to query the database, and return a structure like this (json-y)
// Rows
[
// Row 1
[
{ ColumnName: "id", Value: 1, Type: int },
{ ColumnName: "name", Value: "batman", Type: string },
...
],
// Row 2
[
{ ColumnName: "id", Value: 2, Type: int },
{ ColumnName: "name", Value: "superman", Type: string },
...
]
]
Is there a way to get the Type for a Column using package database/sql in golang?
I'm suspecting that what I want to do is
make an array of interface{} the size of Column(),
then for each column determine it's type,
then fill the array with a pointer to that type,
and then pass the array to Scan()
Which is a little like this code example from sqlx, but without first knowing the Struct that the data would be populating.

Answer 1

You should be able to do it this way:
func printRows(rows *sql.Rows){
colTypes, err := rows.ColumnTypes()
for _,s := range colTypes {
log.Println("cols type:", s.DatabaseTypeName());
}
}

Answer 2

Using database/sql? No (as far as I know).
But you can use this code for arbitrary queries. And json.Marshall() from the json package will use reflection to determine the right way to print a value, so you could have a structure like this:
type Column struct {
ColumnName string
ColumnValue interface{}
ColumnType string
}
And then use reflect.TypeOf(someVariable).String() to get the type for ColumnType.