mysql - GORM 中的多个一对多关系

Question

我有一个 struct GO 中的定义像这样

package models

//StoryStatus indicates the current state of the story
type StoryStatus string

const (
    //Progress indicates a story is currenty being written
    Progress StoryStatus = "progress"
    //Completed indicates a story was completed
    Completed StoryStatus = "completed"
)

//Story holds detials of story
type Story struct {
    ID         int
    Title      string      `gorm:"type:varchar(100);unique_index"`
    Status     StoryStatus `sql:"type ENUM('progress', 'completed');default:'progress'"`
    Paragraphs []Paragraph `gorm:"ForeignKey:StoryID"`
}

//Paragraph is linked to a story
//A story can have around configurable paragraph
type Paragraph struct {
    ID        int
    StoryID   int
    Sentences []Sentence `gorm:"ForeignKey:ParagraphID"`
}

//Sentence are linked to paragraph
//A paragraph can have around configurable paragraphs
type Sentence struct {
    ID          uint
    Value       string
    Status      bool
    ParagraphID uint
}

我正在使用 GORM用于 GO 中的 orm。
如何获取 story 的所有信息基于 story id喜欢所有的 paragraphs以及所有 sentences每个 paragraph .
GORM示例仅显示要使用的 2 个模型 preload

Answer 1

这就是你要找的:

db, err := gorm.Open("mysql", "user:password@/dbname?charset=utf8&parseTime=True&loc=Local")
defer db.Close()

story := &Story{}
db.Preload("Paragraphs").Preload("Paragraphs.Sentences").First(story, 1)

它通过 id = 1 找到故事并预加载其关系

fmt.Printf("%+v\n", story)

这会为您很好地打印出结果

边注:
您可以打开 Gorm 的日志模式，以便您可以查看底层查询、调试或任何其他目的:

db.LogMode(true)