//	db.Where(User{Name: "jinzhu"}).Attrs(User{Email: "******@****.***"}).FirstOrInit(&user)
//	// user -> User{Name: "jinzhu", Age: 20}
//
// [FirstOrCreate]: https://gorm.io/docs/advanced_query.html#FirstOrCreate
// [FirstOrInit]: https://gorm.io/docs/advanced_query.html#FirstOrInit
func (db *DB) Attrs(attrs ...interface{}) (tx *DB) {
	tx = db.getInstance()
	tx.Statement.attrs = attrs
	return
}

const (
	bucketNotificationConfig = "notification.xml"
)

// GetBucketNotificationHandler - This HTTP handler returns event notification configuration
// as per http://docs.aws.amazon.com/AmazonS3/latest/dev/NotificationHowTo.html.
// It returns empty configuration if its not set.
func (api objectAPIHandlers) GetBucketNotificationHandler(w http.ResponseWriter, r *http.Request) {
	ctx := newContext(r, w, "GetBucketNotification")

	//
	// It is recommended that PAX be chosen over GNU unless the target
	// application can only parse GNU formatted archives.
	//
	// Reference:
	//	https://www.gnu.org/software/tar/manual/html_node/Standard.html
	FormatGNU

	// Schily's tar format, which is incompatible with USTAR.
	// This does not cover STAR extensions to the PAX format; these fall under
	// the PAX format.
	formatSTAR

	formatMax
)

			// handle otherwise we would see a signature mismatch.
			// `aws-cli` sets this as part of signed headers.
			//
			// According to
			// http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.20
			// Expect header is always of form:
			//
			//   Expect       =  "Expect" ":" 1#expectation
			//   expectation  =  "100-continue" | expectation-extension
			//

func (db *DB) Update(column string, value interface{}) (tx *DB) {
	tx = db.getInstance()
	tx.Statement.Dest = map[string]interface{}{column: value}
	return tx.callbacks.Update().Execute(tx)
}

// Updates updates attributes using callbacks. values must be a struct or map. Reference: https://gorm.io/docs/update.html#Update-Changed-Fields

	)

	ErrInvalidNumberOfErasureEndpoints = newErrFn(
		"Invalid total number of endpoints for erasure mode",
		"Please provide number of endpoints greater or equal to 2",
		"For more information, please refer to https://min.io/docs/minio/linux/operations/concepts/erasure-coding.html",
	)

	ErrStorageClassValue = newErrFn(

	return subtle.ConstantTimeCompare([]byte(sig1), []byte(sig2)) == 1
}

// doesPolicySignatureMatch - Verify query headers with post policy
//   - http://docs.aws.amazon.com/AmazonS3/latest/API/sigv4-HTTPPOSTConstructPolicy.html
//
// returns ErrNone if the signature matches.
func doesPolicySignatureV4Match(formValues http.Header) (auth.Credentials, APIErrorCode) {
	// Server region.
	region := globalSite.Region

func (a And) Validate() error {
	// > This is used in a Lifecycle Rule Filter to apply a logical AND to two or more predicates.
	// ref: https://docs.aws.amazon.com/AmazonS3/latest/API/API_LifecycleRuleAndOperator.html
	// i.e, predCount >= 2
	var predCount int
	if a.Prefix.set {
		predCount++
	}
	predCount += len(a.Tags)
	if a.ObjectSizeGreaterThan > 0 {
		predCount++
	}
	if a.ObjectSizeLessThan > 0 {
		predCount++

// array position can be safely represented inside a JSON string, embedded
// inside of HTML <script> tags, without any additional escaping.
//
// All values are true except for the ASCII control characters (0-31), the
// double quote ("), the backslash character ("\"), HTML opening and closing
// tags ("<" and ">"), and the ampersand ("&").
var htmlSafeSet = [utf8.RuneSelf]bool{
	' ':      true,

// is different from regular HTTP range header. It only supports the
// form `bytes=first-last` where first and last are zero-based byte
// offsets. See
// http://docs.aws.amazon.com/AmazonS3/latest/API/mpUploadUploadPartCopy.html
// for full details. This function treats an empty rangeString as
// referring to the whole resource.
func parseCopyPartRangeSpec(rangeString string) (hrange *HTTPRangeSpec, err error) {