预期指向结构切片的指针

Question

I'm working on a server in golang.

I have an auth-helper that authenticates the user with a secure token (its a test). The error comes when i make a query (I'm using this dep) in the AuthUsingCredentials function, it outputs the following error:

"Expected pointer to struct slice *[]struct"

If I change the var result *entities.User for var result []entities.User and then print result[0] it works but then it outputs:

"cannot use result[0] (type entities.User) as type *entities.User in argument to ah.userEntityToModel"

The auth helper code:

auth.go

package helpers

import (
  "fmt"

  "server/data/entities"
  "server/data/models"
  "server/interfaces"
)

var AuthHelper *authHelper

type authHelper struct{}

func init() {
    AuthHelper = &authHelper{}
}

func (ah *authHelper) userEntityToModel(_entity *entities.User) (*models.User, error) {
  u := models.NewUser(_entity, db)
    u.Username = _entity.Username

  return u, nil
}

func (ah *authHelper) AuthenticateUsingCredentials(_token string) (interfaces.IUser, error) {
  var result *entities.User
  err := db.Where("Token", "=", _token).Find(result)
  if err != nil {
    return nil, err
  }
  if result == nil {
    return nil, fmt.Errorf("Player '%s' not found", _token)
  }

  playerModel, err := ah.userEntityToModel(result)
  if err != nil {
    return nil, err
  }

  return playerModel, nil
}

Answer 1

Something like this should work.

func (ah *authHelper) AuthenticateUsingCredentials(_token string) (interfaces.IUser, error) {
  var result *[]entities.User
  err := db.Where("Token", "=", _token).Find(result)
  if err != nil {
    return nil, err
  }
  if len(result) <= 0 {
    return nil, fmt.Errorf("Player '%s' not found", _token)
  }

  playerModel, err := ah.userEntityToModel(&(*result)[0])
  if err != nil {
    return nil, err
  }

  return playerModel, nil
}

you are trying to put an slice of users in a function that takes a pointer to a single user.