在Go中使用类似的指针结构来分配结构

Question

I have two structures that are similar and I want to assign one to the other. The first one "Equipment" is the structure used to match the database. The second one "JsonEquipment" is the helper structure to parse JSON data.

Here is the example:

type Equipment struct {
    ID         uint
    CategoryID uint
    Ip         string
    Login      string
    Password   string
}

type JsonEquipment struct {
    ID           *uint
    Category     *string
    Ip           *string
    Login        *string
    Password     *string
}

The pointers are there to check if the field is present or not in the JSON. More info: How to recognize void value and unspecified field when unmarshaling in Go?

So for the moment I created a function with many "if" to check and assign to the Equipment but I wonder if there is a better & cleaner solution.

func CreateEquipment(item JsonEquipment) (Equipment) {
    e := Equipment{}

    if item.ID != nil && !previousEquipment.Auto { // Is the field present & not automatic equipment
        e.ID = *item.ID
    }

    if item.Ip != nil { // Is the field present ?
        e.Ip = *item.Ip
    }

    if item.Login != nil { // Is the field present ?
        e.Login = *item.Login
    }

    [...]
    return e
}

I hope you grasp the idea.

This question is similar to Assign struct with another struct but is different because of the pointers => non pointers struct

Answer 1

EDIT

What I did below works but doesn't do what I intended to. Actually my first code is the only solution to check the difference between empty field and unspecified field.

Here is the demonstration of the differences: https://play.golang.org/p/3tU6paM9Do

---

Fist thanks for everyone's help, and particularly to @Mihailo.

What I end up doing is having my models struct without pointers, i.e:

type Equipment struct {
    ID         uint
    CategoryID uint
    Ip         string
    Login      string
    Password   string
}

and I used a JSON helper struct that has a pointer of model struct, i.e

type JsonHelper struct {
    Equipments    []*Equipment
    [Add other structures here]
}

and finally I parsed the JSON using the JsonHelper struct:

func ParseJSON(inputPath string) JsonHelper {
    // Read configuration file
    content, err := ioutil.ReadFile(inputPath)
    if err != nil {
        log.Println("Error:", err)
    }

    var input JsonHelper

    // Parse JSON from the configuration file
    err = json.Unmarshal(content, &input)
    if err != nil {
        log.Print("Error: ", err)
    }

    return input
}

HTH