CODEWITHSUNDEEP
go
xzeck
xzeck

Reputation: 13

Is there a way to reuse a function for multiple structs in golang?

I'm writing a backend for a project, the backend receives the user data through a POST request encoded in the request body as json.

I have two structures:

struct to store user data during new account creation:

type User struct {
    Guid        string ``
    Name        string `json:"Name"`
    Pass        string `json:"Pass"`
    Username    string `json:"Username"`
    Email       string `json:"Email"`
    Phone       string `json:"Phone"`
    Country     string `json:"Country"`
}

struct to store signin data

type Signin struct {
    Username string `json:"Username"`
    Pass string `json:"Pass"`
}

and a json decoder function (to decode the data from the request body):

func extractAndAssignInfo(req *http.Request, dataStruct interface{}) interface{}{

    decoder := json.NewDecoder(req.Body)
    err := decoder.Decode(&dataStruct)
    if err != nil {
        log.Fatal(err)
    }

    return reflect.ValueOf(dataStruct).Interface()
}

Is there a way to have the extractAndAssignInfo() function to return the struct?

Since the Guid is calculated using a different function, when I try to do

userdata  := ExtractAndAssignInfo(req, User{})

The return value of the function gives a type of map[string]interface {}, if I change the return type to a struct then it won't be a "general purpose" function that can decode and return the required struct.

I'm not sure if this is the best approach to solving it. I would also appreciate any other way I can reuse that same function while returning a struct.

Upvotes: 1

Views: 1521

Answers (1)

Thundercat
Thundercat

Reputation: 120951

Use this function:

func extractAndAssignInfo(req *http.Request, v interface{}) {
    decoder := json.NewDecoder(req.Body)
    err := decoder.Decode(v)
    if err != nil {
        log.Fatal(err)
    }
}

Call it like this to decode the request to a User:

var userData User
extractAndAssignInfo(req, &userData)

and like this to decode to a Signin:

var signin Signin
extractAndAssignInfo(req, &signin)

Side node: It's not a good idea to exit the process on bad request data. Consider returning an error extractAndAssignInfo instead of calling log.Fatal.

Upvotes: 2

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