How to backfill primary key when use this plugin?

[usual2970]

Your Question

type User struct{
  ID int64 `gorm:"column:id;primaryKey"`
  UserId int64 `gorm:"column:user_id"`
}

shard, err := sharding.Register(sharding.Config{
  ShardingKey:         "user_id",
  NumberOfShards:      1,
  PrimaryKeyGenerator: sharding.PKSnowflake,
  ShardingAlgorithm:   getShardFn(1),
}, "users"))
if err != nil {
  return nil, err
}

if err := db.Use(shard); err != nil {
  return nil, err
}

result := db.Create(&user) // pass pointer of data to Create

user.ID             // 0

The document you expected this should be explained

Expected answer

[Yii18]

解决了吗

[huacnlee]

@hyperphoton 看看这个问题

[hyperphoton]

The problem is that when result := db.Create(&user) is executed there is an error at the database level, but you didn't check it, so the user.ID is 0.

Here is a worked example:

package main

import (
	"fmt"

	"gorm.io/driver/postgres"
	"gorm.io/gorm"
	"gorm.io/sharding"
)

type User struct {
	ID     int64 `gorm:"column:id;primaryKey"`
	UserId int64 `gorm:"column:user_id"`
}

func main() {
	dsn := "postgres://localhost:5432/sharding-db?sslmode=disable"
	db, _ := gorm.Open(postgres.New(postgres.Config{DSN: dsn}))

	shard := sharding.Register(sharding.Config{
		ShardingKey:         "user_id",
		NumberOfShards:      1,
		PrimaryKeyGenerator: sharding.PKSnowflake,
	}, "users")

	db.Use(shard)

	user := User{UserId: 42}
	err := db.Create(&user).Error // pass pointer of data to Create
	if err != nil {
		panic(err)
	}

	fmt.Println(user.ID) // 1546765735429144576
}