Gorm - Not fetching data - mysql

Question

I am trying to setup a REST API using Gin and Gorm. Following is my main.go:
package main
import (
"app/config"
"app/service"
"github.com/gin-gonic/gin"
)
func main() {
r := gin.Default()
// Connect to database
config.ConnectDatabase()
r.GET("/books", service.FindBooks)
// Run the server
r.Run()
}
And in my config/setup.go, I am trying to connect to DB like so
package config
import (
"github.com/jinzhu/gorm"
_ "github.com/jinzhu/gorm/dialects/mysql"
)
var DB *gorm.DB
// ConnectDatabase : Setup connection to database
func ConnectDatabase() {
database, err := gorm.Open("mysql", "root:password#tcp(127.0.0.1:3306)/test_db")
database.SingularTable(true)
if err != nil {
panic("Failed to connect to database!")
}
DB = database
}
In my service/book.go, I have the following logic:
package service
import (
"errors"
"app/config"
"app/model"
"fmt"
"net/http"
"github.com/gin-gonic/gin"
)
// FindBooks : Get all books
func FindBooks(c *gin.Context) {
c.JSON(http.StatusOK, gin.H{"data": FindAllBooks()})
}
// FindAllBooks : Fetch all book from DB
func FindAllBooks() []model.Book {
var book []model.Book
config.DB.Find(&book)
for i := 0; i < len(book); i++ {
fmt.Println(book[i])
}
return book
}
And my model/Book.go is defined as follows:
package model
type Book struct {
id int64 `json:"id" gorm:"primary_key"`
label string `json:"label" gorm:"type:varchar(255)"`
}
When I run the application using go run main.go, following is the log I can see:
[GIN-debug] [WARNING] Creating an Engine instance with the Logger and Recovery middleware already attached.
[GIN-debug] [WARNING] Running in "debug" mode. Switch to "release" mode in production.
- using env: export GIN_MODE=release
- using code: gin.SetMode(gin.ReleaseMode)
[GIN-debug] GET /books --> feedconsumer/service.FindBooks (3 handlers)
[GIN-debug] Environment variable PORT is undefined. Using port :8080 by default
[GIN-debug] Listening and serving HTTP on :8080
{0 }
[GIN] 2021/03/09 - 12:43:43 | 200 | 2.313864ms | ::1 | GET "/books"
Basically, the {0 } means the object is not fetched actually. What am I missing here?

Answer 1

GORM uses snake_case for defining field of models. Link to docs
So for your case, it is basically:
package model
type Book struct {
ID int64 `json:"id" gorm:"primary_key"`
Label string `json:"label" gorm:"type:varchar(255)"`
}

Answer 2

I guess you could configure logger for GORM like https://gorm.io/docs/logger.html to be able to see actual db query in those logs. At first glance you are doing everything in the right way as described in https://gorm.io/docs/query.html#Retrieving-all-objects
but I personally met some unpredictable GORM behavior which was not so obvious from doc