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

Question

I am fetching the data using db.QueryRow. Table created using Postgresql with data type jsonb. Below is code in golang

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

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?

Solution

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
}

Comments

[Chandu]

Yes, Its working @MuffinTop. I have lot of data->> fields in my table. Can you please share a piece of code how to use "data as a single field and decode the result with the encoding/json package."

[Chandu]

Thanks a lot @MuffinTop :)

[Chandu]

Just to notify you json.Unmarshal instead of json.Decode. Code working as a charm. thanks again

[Rahul Satal]

The solution really looks good. But I am not able to implement it. I am still getting the same error. You can see my code here - play.golang.org/p/x_P50Ode4QU. Do you have any idea what mistake I am doing?

[Cerise Limón]

@RahulSatal The details of this answer are only relevant to your application if you are using a Postgres JSONB field. Fix your application by passing the address of the individual fields to Scan.

[Rahul Satal]

@CeriseLimón Yes, I am using SQL Server and this fix is not working for it. Thanks for your response.