panic: sql: expected 1 destination arguments in Scan, not <number> golang, pq, sql

Question

I am fetching records from the column data using db.QueryRow from a table in postgresql. The Column has the type jsonb.

Go code

m := Message{}
err := db.QueryRow("SELECT data FROM message WHERE data->>'id'=$1"
                    , id).Scan(m.Id, m.Type, m.Title)

Result

panic: sql: expected 1 destination arguments in Scan, not 3.

As per row.Scan can pass n number of destination arguments. Whats wrong with this code?

Answer 1

The query returns one field per row. The code is scanning for three. Perhaps you want something like:

err := db.QueryRow("SELECT data->>'id', 
                    data->>'type', data->>'title' FROM message 
                    WHERE data->>'id'=$1", id).Scan(m.Id, m.Type, m.Title)

// Also, pass pointers to the values:
err := db.QueryRow("SELECT data->>'id', 
                    data->>'type', data->>'title' FROM message 
                    WHERE data->>'id'=$1", id).Scan(&m.Id, &m.Type, &m.Title)

Another option is to fetch the data as a single field and decode the result with the encoding/json package.

var p []byte
err := db.QueryRow("SELECT data FROM message 
                    WHERE data->>'id'=$1", id).Scan(&p)
if err != nil {
        // handle error
}
var m Message
err := json.Unmarshal(p, &m)
if err != nil {
        // handle error
}