GORM 中的多个一对多关系

Question

我有一个struct定义，GO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GORM在 GO 中用于 orm。我如何story根据story id所有的paragraphs和所有的sentences为每个paragraph.

该GORM示例仅显示要使用的 2 个模型preload

Answer 1

这就是您正在寻找的：

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)

它找到带有 的故事id = 1并预加载其关系

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

这会很好地为您打印结果

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

db.LogMode(true)