Golang GORM有很多关系

Question

I have 2 simple entities, User has many Assets:

type User struct {
    UserId     int     `gorm:"PRIMARY_KEY"`
    Email      string  `gorm:"column:email"`
    FirstName  string  `gorm:"column:firstname"`
    LastName   string  `gorm:"column:lastname"`
    Assets     []Asset `gorm:"foreignkey:user_id"`
}

type Asset struct {
    AssetId int    `gorm:"PRIMARY_KEY"`
    UserId  int    `gorm:"column:user_id"`
    Slug    string `gorm:"column:slug"`
    Address string `gorm:"address"`
}

I want to get a user by the primary id and also collect the assets.

Following the documentation here: http://doc.gorm.io/associations.html#has-many I did the following which gives me an empty array although there are records:

var user app.User
var assets []app.Asset

err := r.DB.Where("user_id = ?", userId).First(&user).Error
if err != nil {
    return nil, err
}

r.DB.Model(&user).Related(&assets)

Changing from:

r.DB.Model(&user).Related(&assets)

to:

r.DB.Model(&user).Related(&user.Assets)

I retrieve a single Asset because GORM is retrieving by asset_id instead of by user_id for some reason. (so if the user_id is 10, it is getting an asset with asset_id -> 10)

What is the correct way to handle the relationship in this case ?

Answer 1

I tried this that way too based on the docs and was unable to get it to work.

What ultimately worked for me was the Preload() func on the db.

Here's an example from some of my code:

err := GetDB().Preload("Ingredients").Find(&flavors).Error