英文:
Gorm - Updating model and appending to a slice
问题
我正在使用gorm，并且有一些关于如何更新模型的问题。我尝试将&Comment附加到BlogPost结构体时出现错误。我还在尝试弄清楚如何将更新后的BlogPost持久化到数据库中。
type BlogPost struct {
ID uint `gorm:"primary_key"`
Content string
Comments []Comment
}
type ParentType int
const (
PT_BlogPost ParentType = 1
PT_Comment = 2
)
type Comment struct {
ID uint `gorm:"primary_key"`
ParentId uint
ParentType ParentType
Comment string
SubComments []Comment
}
func createComment(parentId uint, parentType ParentType) {
switch parentType {
case PT_BlogPost:
var blogPost BlogPost
// 查找博客文章
if err := models.DB.Where("id = ?", parentId).First(&blogPost).Error; err != nil {
return
}
// 将评论添加为博客文章的评论
comment := &models.Comment{
ParentId: parentId,
ParentType: PT_BlogPost,
Author: "",
Content: "",
SubComments: nil,
}
models.DB.Create(&comment)
// TODO 在这里添加评论时出错
blogPost.Comments = append(blogPost.Comments, comment)
// TODO 如何使用gorm更新BlogPost
models.DB.Model(&blogPost).Updates(blogPost)
}
}
以上是你提供的代码的翻译。
英文:
I'm using gorm and have some questions as to how to update the model. I'm getting an error trying to append &Comment to BlogPost struct. Also trying to figure out how to persist the updated BlogPost to DB.
type BlogPost struct {
ID uint `gorm:"primary_key"`
Content string
Comments []Comment
}
type ParentType int
const (
PT_BlogPost ParentType = 1
PT_Comment = 2
)
type Comment struct {
ID uint `gorm:"primary_key"`
ParentId uint
ParentType ParentType
Comment string
SubComments []Comment
}
func createComment(parentId uint, parentType ParentType) {
switch parentType {
case PT_BlogPost:
var blogPost BlogPost
// lookup blog post
if err := models.DB.Where("id = ?", parentId).First(&blogPost).Error; err != nil {
return
}
// add comment as comment on blog post
comment := &models.Comment{
ParentId: parentId,
ParentType: PT_BlogPost,
Author: "",
Content: "",
SubComments: nil,
}
models.DB.Create(&comment)
// TODO Error adding comment here
blogPost.Comments = append(blogPost.Comments, comment)
// TODO How to update BlogPost with gorm
models.DB.Model(&blogPost).Updates(blogPost)
}
}
答案1
得分: 1
你可以使用gorm.Session属性。
type BlogPost struct {
ID uint `gorm:"primary_key"`
Content string
Comments []Comment
}
type ParentType int
const (
PT_BlogPost ParentType = 1
PT_Comment = 2
)
type Comment struct {
ID uint `gorm:"primary_key"`
ParentId uint
ParentType ParentType
Comment string
SubComments []Comment
}
func createComment(parentId uint, parentType ParentType) {
switch parentType {
case PT_BlogPost:
var blogPost BlogPost
// 查找博客文章
if err := models.DB.Where("id = ?", parentId).First(&blogPost).Error; err != nil {
return
}
// 将评论添加为博客文章的评论
comment := &models.Comment{
ParentId: parentId,
ParentType: PT_BlogPost,
Author: "",
Content: "",
SubComments: nil,
}
// TODO 在这里添加评论时出错
blogPost.Comments = append(blogPost.Comments, comment)
// TODO 如何使用gorm更新BlogPost
models.DB.Session(&gorm.Session{FullSaveAssociations: true}).Model(&blogPost).Updates(blogPost)
}
}
FullSaveAssociations: true选项类似于upsert函数。如果你想要更新/创建关联关系，可以使用这个选项。此外，你应该为Comments模型使用references和foreignkey。gorm:"foreignKey:parent_id;references:id"。
如果你想获取更多信息，可以查看下面的链接：
https://gorm.io/docs/associations.html#Auto-Create-Update
英文:
You can use gorm.Session attribute.
type BlogPost struct {
ID uint `gorm:"primary_key"`
Content string
Comments []Comment
}
type ParentType int
const (
PT_BlogPost ParentType = 1
PT_Comment = 2
)
type Comment struct {
ID uint `gorm:"primary_key"`
ParentId uint
ParentType ParentType
Comment string
SubComments []Comment
}
func createComment(parentId uint, parentType ParentType) {
switch parentType {
case PT_BlogPost:
var blogPost BlogPost
// lookup blog post
if err := models.DB.Where("id = ?", parentId).First(&blogPost).Error; err != nil {
return
}
// add comment as comment on blog post
comment := &models.Comment{
ParentId: parentId,
ParentType: PT_BlogPost,
Author: "",
Content: "",
SubComments: nil,
}
// TODO Error adding comment here
blogPost.Comments = append(blogPost.Comments, comment)
// TODO How to update BlogPost with gorm
models.DB.Session(&gorm.Session{FullSaveAssociations: true}).Model(&blogPost).Updates(blogPost)
}
}
FullSaveAssociations: true option works like upsert function. if you wanna update/create with relation, you can use this. also you should to use references and foreignkey for Comments model. gorm:"foreignKey:parent_id;references:id".
if you want to get more information you can look below link;
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