Data Models

Demo Models

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Representing Data in Go

The intermediary state between our database/datastore and output JSON (or HTML views, etc.) is going to be our data model structs in the models/ directory. We will also use this directory for specifying our request/response (frequently JSON) models, as well as the various DB-related models that we might need, i.e., model for the result of a JOIN query.


Since we're storing "gophers" in our MySQL database, let's create a model in models/gopher.go to represent that DB table:

package models

import (

type Gopher struct {
    ID        uint64    `json:"id"`
    FullName  string    `json:"fullName"`
    Headline  string    `json:"headline"`
    AvatarURL string    `json:"avatarUrl"`
    CreatedAt time.Time `json:"-"`
    UpdatedAt time.Time `json:"-"`

const getGophersPaginatedQuery = `SELECT * FROM gopher ORDER BY created_at DESC LIMIT ? OFFSET ?;`

func (gopher *Gopher) FindByID() error {
    return db.Where("id = ?", gopher.ID).First(&gopher).Error

func (gopher *Gopher) Create() error {
    return db.Create(&gopher).Error

func (gopher *Gopher) UpdateMeta() error {
    return db.Table("gopher").Where("id = ?", gopher.ID).Updates(map[string]interface{}{
        "full_name":  gopher.FullName,
        "headline":   gopher.Headline,
        "avatar_url": gopher.AvatarURL,

func GetGophers(limit, offset int64) ([]Gopher, error) {
    var gophers []Gopher
    // Technically this query could go through GORM natively, but just showing off raw SQL query functionality!
    if err := db.Raw(getGophersPaginatedQuery, limit, offset).Scan(&gophers).Error; err != nil {
        return nil, err
    return gophers, nil

User (virtual, for convenience)

Since frequently applications will have users, we'll add the boilerplate model in models/user.go since it is used in some of our middleware code, however, the DB table does not exist, so we will mock our DB methods.

package models

type User struct {
    ID       uint64 `json:"-"`
    FullName string `json:"-"`

func (user *User) FindByID() error {
    user.ID = 1
    user.FullName = "Demo User"
    return nil