db.First() not using primary key name - go

Question

I am writing some sample code to understand gorm but appear to be having an issue with setting up the primary_key value. As a result, the resulting SQL query is broken.
Please see the sample code:
package main
import (
"os"
"fmt"
"time"
"gorm.io/driver/postgres"
"gorm.io/gorm"
)
type Post struct {
id int `json:"id" gorm:"primary_key:id"`
url string `gorm:"url"`
content string `gorm:"content"`
created_at time.Time `gorm:"created_at"`
normalized string `gorm:"normalized"`
account_id int `gorm:"account_id"`
posthash []byte `gorm:"posthash"`
received_at time.Time `gorm:"received_at"`
}
func main() {
dsn := "user=postgres dbname=localtest"
db, err := gorm.Open(postgres.Open(dsn), &gorm.Config{})
if err != nil {
fmt.Println("An error occurred", err)
os.Exit(1)
}
db.AutoMigrate(&Post{})
var post Post
db.First(&post, 1)
fmt.Println(post)
}
When I run this code, I receive the following error:
$ go run gorm_test.go
2020/12/01 00:34:06 /home/farhan/gorm_test.go:32 ERROR: syntax error at or near "=" (SQLSTATE 42601)
[0.128ms] [rows:0] SELECT * FROM "posts" WHERE "posts". = 1 ORDER BY "posts". LIMIT 1
{0 {0 0 <nil>} 0 [] {0 0 <nil>}}
The nature of this error suggests to me that the primary_key value is not set. I tried primaryKey and primarykey, but none appeared to work. Any ideas?

Answer 1

#Shubham Srivastava - Your structure declaration is bad; you need to export fields so gorm can use them Declaring Models
❗️Use exported ID field
In Go, when a field name starts with a lowercase letter that means the field is private (called unexported in Go parlance). Gorm, being a third party package, cannot see inside your struct to know there is an id field, or any other unexported field for that matter.
The solution is to make sure all the fields that need to come from the DB are exported:
type Post struct {
ID uint `json:"id" gorm:"primaryKey"`
...
}