[英]Golang database manager api concept, error with type assertion
The base concept creating a Database Manager API for getting data through an API. 创建数据库管理器API以通过API获取数据的基本概念。 I am using the GORM for getting data of the instances of the strcuts.
我正在使用GORM来获取strcuts实例的数据。 So there is 300-400 struct which represents the tables.
所以有300-400结构代表表。
type Users struct {
ID int64
Name string
}
type Categories struct {
ID int64
Category string
}
The next step I implement a function which is return the correct instance of the struct by table name, what I get through the API endpoint param. 下一步我实现一个函数,它通过表名返回结构的正确实例,我通过API端点参数得到了什么。
func GetModel(model string) interface{} {
switch model {
case "users":
return Users{}
case "categories"
return Categories{}
}
return false
}
After there is an operations struct where the only one field is the DB. 在有一个操作结构之后,只有一个字段是DB。 There is methods, for example the GetLast() where I want to use the GORM db.Last(&users) function.
有方法,例如GetLast(),我想使用GORM db.Last(&users)函数。
func (o Operations) GetLast(model string) interface{} {
modelStruct := GetModel(model)
.
.
.
return o.DB.Last(&modelStruct)
}
There is points so this is what I don't know. 有分,所以这是我不知道的。 The current solution is not working because in this case it is an interface{} I need make a type assertion more info in this question .
当前的解决方案不起作用,因为在这种情况下它是一个接口{}我需要在这个问题中做一个类型断言更多的信息 。 The type assertion is looks like:
类型断言看起来像:
func (o Operations) GetLast(model string) interface{} {
modelStruct := GetModel(model)
.
test := modelStruct.(Users)
.
return o.DB.Last(&test)
}
This solution working, but in this case I lost the modularity. 这个解决方案有效,但在这种情况下我失去了模块化。 I try using the
reflect.TypeOf(modelStruct)
, but it is also not working because the result of the reflect.TypeOf is a reflect.Type, with is not a golang type. 我尝试使用
reflect.TypeOf(modelStruct)
,但它也无法正常工作,因为reflect.TypeOf的结果是一个reflect.Type,而不是golang类型。
Basically I solved the problem, for getting the model as a pointer, and after I return it back as a json file. 基本上我解决了这个问题,将模型作为指针,然后将其作为json文件返回。
So my model is the following: 所以我的模型如下:
var Models = map[string]interface{}{
"users": new(Users),
"categories": new(Categories),
}
And it is return back a new model by table type. 它按表格类型返回一个新模型。 what I can use for gorm First() function.
我可以用于gorm First()函数。 Then json Marshal it, and return.
然后json Marshal吧,并返回。
func (o Operation) First(model string, query url.Values) string {
modelStruct := Models[model]
db := o.DB
db.First(modelStruct)
response, _ := json.Marshal(modelStruct)
clear(modelStruct)
return string(response)
}
Before the return I clear the model pointer because the First() function store callbacks for the latest queries. 在返回之前,我清除了模型指针,因为First()函数存储了最新查询的回调。
func clear(v interface{}) {
p := reflect.ValueOf(v).Elem()
p.Set(reflect.Zero(p.Type()))
}
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.