英文:
How to modify fields of a Golang struct to another type before rendering to jSON?
问题
我们正在我们的API中添加一个包含参数，API客户端可以使用它来包含关联关系。
// 请求
GET /api/events?include=team1
[{
"id": <event_id>,
"name": <event_name>,
"team1": {
"id": <team_id>,
"name": <team_name>
}
}]
// 代码
type Event struct {
ID int64 gorm:"primary_key" json:"id"
Team1ID int64 json:"-"
Team1 Team json:"team1"
}
var event Event
Db.Preload("Team1").Find(&event, 1)
c.JSON(http.StatusOK, event)
但我们还想能够这样做：
// 请求
GET /api/events
[{
"id": <event_id>,
"name": <event_name>,
"team1": <team1_id>
}]
现在，team1字段只是一个id。
在Go中有没有简单的方法可以做到这一点？
我认为我可以使用map[string]interface{}来实现这一点，比如在从数据库中获取事件之后，将事件结构转换为map[string]interface{}并进行修改。但我想知道是否有更简单的解决方案。
这是我尝试使用map[string]interface{}的代码-https://play.golang.org/p/-19MWtqhE3。代码非常冗长。我的想法是为每个结构使用map[string]interface{}，然后组合包含相关资源的顶级资源。
有更好的方法吗？
英文:
We are adding an include parameter in our API w/c API clients can use to include relationships
// requestGET /api/events?include=team1[{"id": <event_id>,"name": <event_name>,"team1": {"id": <team_id>,"name": <team_name>}}]// codetype Event struct {ID int64 `gorm:"primary_key" json:"id"`Team1ID int64 `json:"-"`Team1 Team `json:"team1"`}var event EventDb.Preload("Team1").Find(&event, 1)c.JSON(http.StatusOK, event)
But we also want to be able to do this:
// requestGET /api/events[{"id": <event_id>,"name": <event_name>,"team1": <team1_id>}]
The team1 field is now just an id.
Is there an easy way to do this in Go?
I think I can do this by using a map[string]interface{}, like after fetching the events in the db, convert the event structs to a map[string]interface{} and do the modifications. But I'm wondering if theres an easier solution.
Here's my attempt in using map[string]interface{} - https://play.golang.org/p/-19MWtqhE3 . The code is very verbose. The idea is to use map[string]interface{} for every struct then compose the top level resource that includes the related resources.
What's a better way to do this?
答案1
得分: 1
我认为最清晰的方法是使用两个不同的函数。
type Event struct {ID int64 `gorm:"primary_key" json:"id"`Team1ID int64 `json:"-"`Team1 Team `json:"team1"`}type Team struct {ID int64 `gorm:"primary_key" json:"id"`Name string `json:"name"`}type EventInformations struct {ID int64 `json:"id"`Name string `json:"name"`Team1 `json"team1"`}type EventInformationsTeamIncluded struct {ID int64 `json:"id"`Name string `json:"name"`Team1 Team `json:"team1"`}func (e *Event) Informations() *EventInformations {return &EventInformations{ID: e.ID,Name: e.Name,Team1: e.Team1,}}func (e *Event) InformationsTeamIncluded() *EventInformationsTeamIncluded {return &EventInformations{ID: e.ID,Name: e.Name,Team1: &Team{...},}}
稍后只需调用：
event.Informations();
或者
event.InformationsTeamIncluded();
你的代码/示例中有一些不太合理的地方：
- 变量
Team1有点奇怪，因为结构体中只有一个值，所以如果你不打算在结构体中添加一些Team，我建议将其替换为Team；如果你计划有多个Team，则将其替换为Teams []*Team。 - 第二个问题是在你的示例中，你向同一个名称返回了两个不同的值，这取决于上下文。我建议在某种情况下返回
team1_id而不是team1。
编辑：不使用结构体的情况下：
func (e *Event) Informations() *map[string]interface{} {return &map[string]interface{}{"ID": e.ID,"Name": e.Name,"Team1": e.Team1,}}func (e *Event) InformationsTeamIncluded() *map[string]interface{} {// 重用之前的函数data := e.Informations()// 添加team1的信息data["team1"] = map[string]interface{}{"ID": e.Team1.ID,"Name": e.Team1.Name,}return data}
英文:
I think the most cleaner way is to use two different functions.
type Event struct {ID int64 `gorm:"primary_key" json:"id"`Team1ID int64 `json:"-"`Team1 Team `json:"team1"`}type Team struct {ID int64 `gorm:"primary_key" json:"id"`Name string `json:"name"`}type EventInformations struct {ID int64 `json:"id"`Name string `json:"name"`Team1 `json"team1"`}type EventInformationsTeamIncluded struct {ID int64 `json:"id"`Name string `json:"name"`Team1 Team `json:"team1"`}func (e *Event) Informations() *EventInformations {return &EventInformations{ID: e.ID,Name: e.Name,Team1: e.Team1,},}func (e *Event) InformationsTeamIncluded() *EventInformationsTeamIncluded {return &EventInformations{ID: e.ID,Name: e.Name,Team1: &Team{...},}}
So later just call
event.Informations();
Or
event.InformationsTeamIncluded();
There is something not very logical in your code/examples:
- The var
Team1is a little bit weird cause there is only one value in the struct so if you don't have plan to add someTeamin struct I suggest to replace it by Team if you plan to have any Team replace it byTeams []*Team - The second thing is in your example your return two differents values to a same name, it depends of the context I suggest in one case to return
team1_idinstead ofteam1
EDIT : without struct
func (e *Event) Informations() *map[string]interface{} {return &map[string]interface{}{"ID": e.ID,"Name": e.Name,"Team1": e.Team1,},}func (e *Event) InformationsTeamIncluded() *map[string]interface{} {// Reuse the previous functiondata := e.Informations()// Add the team1 informationsdata["team1"] = map[string]interface{}{ID: e.Team1.ID,Name: e.Team1.Name,}return data}
答案2
得分: 1
实际上，你可以将team1设置为一个接口，然后转换其值，当然要进行适当的验证。
type Event struct {ID int64 `gorm:"primary_key" json:"id"`Team1ID int64 `json:"-"`Team1 interface{} `json:"team1"`Team1Struct Team `json:"-"`}
然后进行评估：
if value, ok := evt.Team1.(Team); ok {// 传递的值是一个Team结构体event.Team1Struct = value} else {// 传递的值是一个字符串（或其他类型...）}
希望对你有所帮助！
英文:
Actually you could just set the team1 to be an interface and then cast it's value, obviously making the proper validations.
type Event struct {ID int64 `gorm:"primary_key" json:"id"`Team1ID int64 `json:"-"`Team1 interface{} `json:"team1"`Team1Struct Team `json:"-"`}
And then evaluate:
if value, ok := evt.Team1.(Team); ok {// The passed value is a Team structevent.Team1Struct = value} else {// The passed value is a string (or something else...)}
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