json: unsupported type: func() time.Time Marshaling CreatedAt, UpdatedAt and DeletedAt

Question

How can I resolve the error json: unsupported type: func() time.Time trying to return a newly saved model back as JSON.

user := database.DBConn.Create(&newUser)
return c.Status(http.StatusCreated).JSON(user) // fiber response

Tried ignoring the timestamp fields.

type User struct {
    gorm.Model
    ID uuid.UUID `gorm:"primary_key;type:uuid;default:uuid_generate_v4()"`
    Phone     string `json:"phone"`
    FirstName string `json:"firstName"`
    LastName  string `json:"lastName"`
    Email string `json:"email"`
    CreatedAt time.Time `json:"-"`
    UpdatedAt time.Time `json:"-"`
    DeletedAt time.Time `json:"-"`
}

Also tried

CreatedAt time.Time `gorm:"type:timestamp" json:"created_at,string,omitempty"`
UpdatedAt time.Time `gorm:"type:timestamp" json:"updated_at,string,omitempty"`
DeletedAt time.Time `gorm:"type:timestamp" json:"deleted_at,string,omitempty"`

And

CreatedAt time.Time `gorm:"type:datetime" json:"created_at,string,omitempty"`
UpdatedAt time.Time `gorm:"type:datetime" json:"updated_at,string,omitempty"`
DeletedAt time.Time `gorm:"type:datetime" json:"deleted_at,string,omitempty"`

Using gorm v1.20.12 and Go 1.15.6

Answer 1

I encountered similar error and discovered that user := database.DBConn.Create(&newUser) returns a *gorm.DB which cannot be marshaled by JSON.

Instead use this:

database.DBConn.Create(&newUser)
return c.Status(http.StatusCreated).JSON(newUser)

It worked for me and I hope it works for you as well.