如何将JSON文档中的字符串值解组为一个int类型的变量? [英] How do I unmarshal a string value from a JSON document into a variable of type int?
问题描述
类型User结构{
名字字符串`json:firstname,omitemptyvalidate:
LastName字符串`json:lastname,omitemptyvalidate:required`
NumberofDays int`json:numberofdays,stringvalidate:min = 0,max = 100`
NumberofDays的值作为字符串从服务器传递,但我想检查是否它在范围内并以int的形式存储。
例如: user:=& User {Michael,Msk,3}
我得到'不能将字符串解组为'int类型的Go值'。
我不确定如何对int进行类型转换并进行验证
删除结构标记中的逗号后的空格,例如 json:numberofdays,string
应该是 json:numberofdays,string
。有了空格, json
包将忽略字符串
部分,因此会出现错误消息。如果没有空间,错误就会消失,行为也会如预期。
json
package struct tags: https://golang.org/ pkg / encoding / json /#Marshal
My struct:
type User struct {
FirstName string `json:"firstname, omitempty" validate:"required"`
LastName string `json:"lastname, omitempty" validate:"required"`
NumberofDays int `json:"numberofdays, string" validate:"min=0,max=100"`
}
Value for NumberofDays is passed as string from the server but I want to check if it is within range and store as int.
Ex: user := &User{"Michael","Msk","3"}
I'm getting 'cannot unmarshal string into Go value of type int'.
I'm not sure how to typecast to int and do the validation
Remove the space after the comma in the struct tags, e.g. json:"numberofdays, string"
should be json:"numberofdays,string"
. With the space, the json
package ignores the string
part, hence the error message you're getting. Without the space, the error goes away and behavior is as expected.
Demo comparing the two here: https://play.golang.org/p/AUImnw_PIS
Documentation of json
package struct tags: https://golang.org/pkg/encoding/json/#Marshal
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