Simple and Powerful ORM for Go, support mysql,postgres,tidb,sqlite3,sqlite,mssql,oracle,cockroach https://xorm.io
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// Copyright 2020 The Xorm Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package utils
import (
"reflect"
"time"
)
// Zeroable represents an interface which could know if it's a zero value
type Zeroable interface {
IsZero() bool
}
var nilTime *time.Time
// IsZero returns false if k is nil or has a zero value
func IsZero(k interface{}) bool {
if k == nil {
return true
}
switch t := k.(type) {
case int:
return t == 0
case int8:
return t == 0
case int16:
return t == 0
case int32:
return t == 0
case int64:
return t == 0
case uint:
return t == 0
case uint8:
return t == 0
case uint16:
return t == 0
case uint32:
return t == 0
case uint64:
return t == 0
case float32:
return t == 0
case float64:
return t == 0
case bool:
return !t
case string:
return t == ""
case *time.Time:
return t == nilTime || IsTimeZero(*t)
case time.Time:
return IsTimeZero(t)
case Zeroable:
return k.(Zeroable) == nil || k.(Zeroable).IsZero()
case reflect.Value: // for go version less than 1.13 because reflect.Value has no method IsZero
return IsValueZero(k.(reflect.Value))
}
return IsValueZero(reflect.ValueOf(k))
}
var zeroType = reflect.TypeOf((*Zeroable)(nil)).Elem()
// IsValueZero returns true if the reflect Value is a zero
func IsValueZero(v reflect.Value) bool {
switch v.Kind() {
case reflect.Chan, reflect.Func, reflect.Interface, reflect.Map, reflect.Slice:
return v.IsNil()
case reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int, reflect.Int64:
return v.Int() == 0
case reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint, reflect.Uint64:
return v.Uint() == 0
case reflect.String:
return v.Len() == 0
case reflect.Ptr:
if v.IsNil() {
return true
}
return IsValueZero(v.Elem())
case reflect.Struct:
return IsStructZero(v)
case reflect.Array:
return IsArrayZero(v)
}
return false
}
// IsStructZero returns true if the Value is a struct and all fields is zero
func IsStructZero(v reflect.Value) bool {
if !v.IsValid() || v.NumField() == 0 {
return true
}
if v.Type().Implements(zeroType) {
f := v.MethodByName("IsZero")
if f.IsValid() {
res := f.Call(nil)
return len(res) == 1 && res[0].Bool()
}
}
for i := 0; i < v.NumField(); i++ {
field := v.Field(i)
switch field.Kind() {
case reflect.Ptr:
field = field.Elem()
fallthrough
case reflect.Struct:
if !IsStructZero(field) {
return false
}
default:
if field.CanInterface() && !IsZero(field.Interface()) {
return false
}
}
}
return true
}
// IsArrayZero returns true is a slice of array is zero
func IsArrayZero(v reflect.Value) bool {
if !v.IsValid() || v.Len() == 0 {
return true
}
for i := 0; i < v.Len(); i++ {
if !IsZero(v.Index(i).Interface()) {
return false
}
}
return true
}
// represents all zero times
const (
ZeroTime0 = "0000-00-00 00:00:00"
ZeroTime1 = "0001-01-01 00:00:00"
)
// IsTimeZero return true if a time is zero
func IsTimeZero(t time.Time) bool {
return t.IsZero() || t.Format("2006-01-02 15:04:05") == ZeroTime0 ||
t.Format("2006-01-02 15:04:05") == ZeroTime1
}