不支持的型号* settingsmodel.Settings？

Question

I'm using this ORM library for PostgreSQL: https://godoc.org/github.com/go-pg/pg#example-DB-Select and I'm having an odd issue which I don't understand.

I'm trying to SELECT data from my settings table to later update that value with a function.

package settingsmodel

import (
    . "database"
)

type Settings struct {
    Id int64
    SiteName string
}

func Set(newValue string) bool {
    site := &Settings {
        SiteName: "MySite",
    }

    err := Db.Select(&site)
    if err != nil {
        panic(err) // This is where it panics
    }

    site.SiteName = newValue
    err = Db.Update(site)
    if err != nil {
        panic(err)
    }

    return true
}

The error I'm getting is panic: pg: Model(unsupported *settingsmodel.Settings)

I have another function (in the same file) where I get the site name and it works perfectly fine:

func Get() string {
    var site Settings

    err := Db.Model(&site).First()
    if err != nil {
        panic(err)
    }

    return site.SiteName
}

I really don't understand why it's not working. Any help? Thanks!

Answer 1

In the working example, you're passing a pointer to settings; in the first (non-working) example, you're passing a pointer to a pointer:

// &Settings - site is a pointer to a Settings struct
site := &Settings {
    SiteName: "MySite",
}

// &site - pass a pointer to site, which is already a pointer
err := Db.Select(&site)

vs the working one:

// site is a value, not a pointer
var site Settings

// Pass a pointer to the value
err := Db.Model(&site).First()