src/database/sql/convert.go - go - Git at Google

 // Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.

 // Type conversions for Scan.

 package sql

 import (
 	"database/sql/driver"
 	"errors"
 	"fmt"
 	"reflect"
 	"strconv"
 	"time"
 )

 var errNilPtr = errors.New("destination pointer is nil") // embedded in descriptive error

 func describeNamedValue(nv *driver.NamedValue) string {
 	if len(nv.Name) == 0 {
 		return fmt.Sprintf("$%d", nv.Ordinal)
 	}
 	return fmt.Sprintf("with name %q", nv.Name)
 }

 // driverArgs converts arguments from callers of Stmt.Exec and
 // Stmt.Query into driver Values.
 //
 // The statement ds may be nil, if no statement is available.
 func driverArgs(ds *driverStmt, args []interface{}) ([]driver.NamedValue, error) {
 	nvargs := make([]driver.NamedValue, len(args))
 	var si driver.Stmt
 	if ds != nil {
 		si = ds.si
 	}
 	cc, ok := si.(driver.ColumnConverter)

 	// Normal path, for a driver.Stmt that is not a ColumnConverter.
 	if !ok {
 		for n, arg := range args {
 			var err error
 			nv := &nvargs[n]
 			nv.Ordinal = n + 1
 			if np, ok := arg.(NamedParam); ok {
 				arg = np.Value
 				nvargs[n].Name = np.Name
 			}
 			nv.Value, err = driver.DefaultParameterConverter.ConvertValue(arg)

 			if err != nil {
 				return nil, fmt.Errorf("sql: converting Exec argument %s type: %v", describeNamedValue(nv), err)
 			}
 		}
 		return nvargs, nil
 	}

 	// Let the Stmt convert its own arguments.
 	for n, arg := range args {
 		nv := &nvargs[n]
 		nv.Ordinal = n + 1
 		if np, ok := arg.(NamedParam); ok {
 			arg = np.Value
 			nv.Name = np.Name
 		}
 		// First, see if the value itself knows how to convert
 		// itself to a driver type. For example, a NullString
 		// struct changing into a string or nil.
 		if vr, ok := arg.(driver.Valuer); ok {
 			sv, err := callValuerValue(vr)
 			if err != nil {
 				return nil, fmt.Errorf("sql: argument %s from Value: %v", describeNamedValue(nv), err)
 			}
 			if !driver.IsValue(sv) {
 				return nil, fmt.Errorf("sql: argument %s: non-subset type %T returned from Value", describeNamedValue(nv), sv)
 			}
 			arg = sv
 		}

 		// Second, ask the column to sanity check itself. For
 		// example, drivers might use this to make sure that
 		// an int64 values being inserted into a 16-bit
 		// integer field is in range (before getting
 		// truncated), or that a nil can't go into a NOT NULL
 		// column before going across the network to get the
 		// same error.
 		var err error
 		ds.Lock()
 		nv.Value, err = cc.ColumnConverter(n).ConvertValue(arg)
 		ds.Unlock()
 		if err != nil {
 			return nil, fmt.Errorf("sql: converting argument %s type: %v", describeNamedValue(nv), err)
 		}
 		if !driver.IsValue(nv.Value) {
 			return nil, fmt.Errorf("sql: for argument %s, driver ColumnConverter error converted %T to unsupported type %T",
 				describeNamedValue(nv), arg, nv.Value)
 		}
 	}

 	return nvargs, nil
 }

 // convertAssign copies to dest the value in src, converting it if possible.
 // An error is returned if the copy would result in loss of information.
 // dest should be a pointer type.
 func convertAssign(dest, src interface{}) error {
 	// Common cases, without reflect.
 	switch s := src.(type) {
 	case string:
 		switch d := dest.(type) {
 		case *string:
 			if d == nil {
 				return errNilPtr
 			}
 			*d = s
 			return nil
 		case *[]byte:
 			if d == nil {
 				return errNilPtr
 			}
 			*d = []byte(s)
 			return nil
 		}
 	case []byte:
 		switch d := dest.(type) {
 		case *string:
 			if d == nil {
 				return errNilPtr
 			}
 			*d = string(s)
 			return nil
 		case *interface{}:
 			if d == nil {
 				return errNilPtr
 			}
 			*d = cloneBytes(s)
 			return nil
 		case *[]byte:
 			if d == nil {
 				return errNilPtr
 			}
 			*d = cloneBytes(s)
 			return nil
 		case *RawBytes:
 			if d == nil {
 				return errNilPtr
 			}
 			*d = s
 			return nil
 		}
 	case time.Time:
 		switch d := dest.(type) {
 		case *string:
 			*d = s.Format(time.RFC3339Nano)
 			return nil
 		case *[]byte:
 			if d == nil {
 				return errNilPtr
 			}
 			*d = []byte(s.Format(time.RFC3339Nano))
 			return nil
 		}
 	case nil:
 		switch d := dest.(type) {
 		case *interface{}:
 			if d == nil {
 				return errNilPtr
 			}
 			*d = nil
 			return nil
 		case *[]byte:
 			if d == nil {
 				return errNilPtr
 			}
 			*d = nil
 			return nil
 		case *RawBytes:
 			if d == nil {
 				return errNilPtr
 			}
 			*d = nil
 			return nil
 		}
 	}

 	var sv reflect.Value

 	switch d := dest.(type) {
 	case *string:
 		sv = reflect.ValueOf(src)
 		switch sv.Kind() {
 		case reflect.Bool,
 			reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64,
 			reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64,
 			reflect.Float32, reflect.Float64:
 			*d = asString(src)
 			return nil
 		}
 	case *[]byte:
 		sv = reflect.ValueOf(src)
 		if b, ok := asBytes(nil, sv); ok {
 			*d = b
 			return nil
 		}
 	case *RawBytes:
 		sv = reflect.ValueOf(src)
 		if b, ok := asBytes([]byte(*d)[:0], sv); ok {
 			*d = RawBytes(b)
 			return nil
 		}
 	case *bool:
 		bv, err := driver.Bool.ConvertValue(src)
 		if err == nil {
 			*d = bv.(bool)
 		}
 		return err
 	case *interface{}:
 		*d = src
 		return nil
 	}

 	if scanner, ok := dest.(Scanner); ok {
 		return scanner.Scan(src)
 	}

 	dpv := reflect.ValueOf(dest)
 	if dpv.Kind() != reflect.Ptr {
 		return errors.New("destination not a pointer")
 	}
 	if dpv.IsNil() {
 		return errNilPtr
 	}

 	if !sv.IsValid() {
 		sv = reflect.ValueOf(src)
 	}

 	dv := reflect.Indirect(dpv)
 	if sv.IsValid() && sv.Type().AssignableTo(dv.Type()) {
 		switch b := src.(type) {
 		case []byte:
 			dv.Set(reflect.ValueOf(cloneBytes(b)))
 		default:
 			dv.Set(sv)
 		}
 		return nil
 	}

 	if dv.Kind() == sv.Kind() && sv.Type().ConvertibleTo(dv.Type()) {
 		dv.Set(sv.Convert(dv.Type()))
 		return nil
 	}

 	switch dv.Kind() {
 	case reflect.Ptr:
 		if src == nil {
 			dv.Set(reflect.Zero(dv.Type()))
 			return nil
 		} else {
 			dv.Set(reflect.New(dv.Type().Elem()))
 			return convertAssign(dv.Interface(), src)
 		}
 	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
 		s := asString(src)
 		i64, err := strconv.ParseInt(s, 10, dv.Type().Bits())
 		if err != nil {
 			err = strconvErr(err)
 			return fmt.Errorf("converting driver.Value type %T (%q) to a %s: %v", src, s, dv.Kind(), err)
 		}
 		dv.SetInt(i64)
 		return nil
 	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
 		s := asString(src)
 		u64, err := strconv.ParseUint(s, 10, dv.Type().Bits())
 		if err != nil {
 			err = strconvErr(err)
 			return fmt.Errorf("converting driver.Value type %T (%q) to a %s: %v", src, s, dv.Kind(), err)
 		}
 		dv.SetUint(u64)
 		return nil
 	case reflect.Float32, reflect.Float64:
 		s := asString(src)
 		f64, err := strconv.ParseFloat(s, dv.Type().Bits())
 		if err != nil {
 			err = strconvErr(err)
 			return fmt.Errorf("converting driver.Value type %T (%q) to a %s: %v", src, s, dv.Kind(), err)
 		}
 		dv.SetFloat(f64)
 		return nil
 	}

 	return fmt.Errorf("unsupported Scan, storing driver.Value type %T into type %T", src, dest)
 }

 func strconvErr(err error) error {
 	if ne, ok := err.(*strconv.NumError); ok {
 		return ne.Err
 	}
 	return err
 }

 func cloneBytes(b []byte) []byte {
 	if b == nil {
 		return nil
 	} else {
 		c := make([]byte, len(b))
 		copy(c, b)
 		return c
 	}
 }

 func asString(src interface{}) string {
 	switch v := src.(type) {
 	case string:
 		return v
 	case []byte:
 		return string(v)
 	}
 	rv := reflect.ValueOf(src)
 	switch rv.Kind() {
 	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
 		return strconv.FormatInt(rv.Int(), 10)
 	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
 		return strconv.FormatUint(rv.Uint(), 10)
 	case reflect.Float64:
 		return strconv.FormatFloat(rv.Float(), 'g', -1, 64)
 	case reflect.Float32:
 		return strconv.FormatFloat(rv.Float(), 'g', -1, 32)
 	case reflect.Bool:
 		return strconv.FormatBool(rv.Bool())
 	}
 	return fmt.Sprintf("%v", src)
 }

 func asBytes(buf []byte, rv reflect.Value) (b []byte, ok bool) {
 	switch rv.Kind() {
 	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
 		return strconv.AppendInt(buf, rv.Int(), 10), true
 	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
 		return strconv.AppendUint(buf, rv.Uint(), 10), true
 	case reflect.Float32:
 		return strconv.AppendFloat(buf, rv.Float(), 'g', -1, 32), true
 	case reflect.Float64:
 		return strconv.AppendFloat(buf, rv.Float(), 'g', -1, 64), true
 	case reflect.Bool:
 		return strconv.AppendBool(buf, rv.Bool()), true
 	case reflect.String:
 		s := rv.String()
 		return append(buf, s...), true
 	}
 	return
 }

 var valuerReflectType = reflect.TypeOf((*driver.Valuer)(nil)).Elem()

 // callValuerValue returns vr.Value(), with one exception:
 // If vr.Value is an auto-generated method on a pointer type and the
 // pointer is nil, it would panic at runtime in the panicwrap
 // method. Treat it like nil instead.
 // Issue 8415.
 //
 // This is so people can implement driver.Value on value types and
 // still use nil pointers to those types to mean nil/NULL, just like
 // string/*string.
 //
 // This function is mirrored in the database/sql/driver package.
 func callValuerValue(vr driver.Valuer) (v driver.Value, err error) {
 	if rv := reflect.ValueOf(vr); rv.Kind() == reflect.Ptr &&
 		rv.IsNil() &&
 		rv.Type().Elem().Implements(valuerReflectType) {
 		return nil, nil
 	}
 	return vr.Value()
 }
	// Copyright 2011 The Go Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style
	// license that can be found in the LICENSE file.

	// Type conversions for Scan.

	package sql

	import (
	"database/sql/driver"
	"errors"
	"fmt"
	"reflect"
	"strconv"
	"time"
	)

	var errNilPtr = errors.New("destination pointer is nil") // embedded in descriptive error

	func describeNamedValue(nv *driver.NamedValue) string {
	if len(nv.Name) == 0 {
	return fmt.Sprintf("$%d", nv.Ordinal)
	}
	return fmt.Sprintf("with name %q", nv.Name)
	}

	// driverArgs converts arguments from callers of Stmt.Exec and
	// Stmt.Query into driver Values.
	//
	// The statement ds may be nil, if no statement is available.
	func driverArgs(ds *driverStmt, args []interface{}) ([]driver.NamedValue, error) {
	nvargs := make([]driver.NamedValue, len(args))
	var si driver.Stmt
	if ds != nil {
	si = ds.si
	}
	cc, ok := si.(driver.ColumnConverter)

	// Normal path, for a driver.Stmt that is not a ColumnConverter.
	if !ok {
	for n, arg := range args {
	var err error
	nv := &nvargs[n]
	nv.Ordinal = n + 1
	if np, ok := arg.(NamedParam); ok {
	arg = np.Value
	nvargs[n].Name = np.Name
	}
	nv.Value, err = driver.DefaultParameterConverter.ConvertValue(arg)

	if err != nil {
	return nil, fmt.Errorf("sql: converting Exec argument %s type: %v", describeNamedValue(nv), err)
	}
	}
	return nvargs, nil
	}

	// Let the Stmt convert its own arguments.
	for n, arg := range args {
	nv := &nvargs[n]
	nv.Ordinal = n + 1
	if np, ok := arg.(NamedParam); ok {
	arg = np.Value
	nv.Name = np.Name
	}
	// First, see if the value itself knows how to convert
	// itself to a driver type. For example, a NullString
	// struct changing into a string or nil.
	if vr, ok := arg.(driver.Valuer); ok {
	sv, err := callValuerValue(vr)
	if err != nil {
	return nil, fmt.Errorf("sql: argument %s from Value: %v", describeNamedValue(nv), err)
	}
	if !driver.IsValue(sv) {
	return nil, fmt.Errorf("sql: argument %s: non-subset type %T returned from Value", describeNamedValue(nv), sv)
	}
	arg = sv
	}

	// Second, ask the column to sanity check itself. For
	// example, drivers might use this to make sure that
	// an int64 values being inserted into a 16-bit
	// integer field is in range (before getting
	// truncated), or that a nil can't go into a NOT NULL
	// column before going across the network to get the
	// same error.
	var err error
	ds.Lock()
	nv.Value, err = cc.ColumnConverter(n).ConvertValue(arg)
	ds.Unlock()
	if err != nil {
	return nil, fmt.Errorf("sql: converting argument %s type: %v", describeNamedValue(nv), err)
	}
	if !driver.IsValue(nv.Value) {
	return nil, fmt.Errorf("sql: for argument %s, driver ColumnConverter error converted %T to unsupported type %T",
	describeNamedValue(nv), arg, nv.Value)
	}
	}

	return nvargs, nil
	}

	// convertAssign copies to dest the value in src, converting it if possible.
	// An error is returned if the copy would result in loss of information.
	// dest should be a pointer type.
	func convertAssign(dest, src interface{}) error {
	// Common cases, without reflect.
	switch s := src.(type) {
	case string:
	switch d := dest.(type) {
	case *string:
	if d == nil {
	return errNilPtr
	}
	*d = s
	return nil
	case *[]byte:
	if d == nil {
	return errNilPtr
	}
	*d = []byte(s)
	return nil
	}
	case []byte:
	switch d := dest.(type) {
	case *string:
	if d == nil {
	return errNilPtr
	}
	*d = string(s)
	return nil
	case *interface{}:
	if d == nil {
	return errNilPtr
	}
	*d = cloneBytes(s)
	return nil
	case *[]byte:
	if d == nil {
	return errNilPtr
	}
	*d = cloneBytes(s)
	return nil
	case *RawBytes:
	if d == nil {
	return errNilPtr
	}
	*d = s
	return nil
	}
	case time.Time:
	switch d := dest.(type) {
	case *string:
	*d = s.Format(time.RFC3339Nano)
	return nil
	case *[]byte:
	if d == nil {
	return errNilPtr
	}
	*d = []byte(s.Format(time.RFC3339Nano))
	return nil
	}
	case nil:
	switch d := dest.(type) {
	case *interface{}:
	if d == nil {
	return errNilPtr
	}
	*d = nil
	return nil
	case *[]byte:
	if d == nil {
	return errNilPtr
	}
	*d = nil
	return nil
	case *RawBytes:
	if d == nil {
	return errNilPtr
	}
	*d = nil
	return nil
	}
	}

	var sv reflect.Value

	switch d := dest.(type) {
	case *string:
	sv = reflect.ValueOf(src)
	switch sv.Kind() {
	case reflect.Bool,
	reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64,
	reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64,
	reflect.Float32, reflect.Float64:
	*d = asString(src)
	return nil
	}
	case *[]byte:
	sv = reflect.ValueOf(src)
	if b, ok := asBytes(nil, sv); ok {
	*d = b
	return nil
	}
	case *RawBytes:
	sv = reflect.ValueOf(src)
	if b, ok := asBytes([]byte(*d)[:0], sv); ok {
	*d = RawBytes(b)
	return nil
	}
	case *bool:
	bv, err := driver.Bool.ConvertValue(src)
	if err == nil {
	*d = bv.(bool)
	}
	return err
	case *interface{}:
	*d = src
	return nil
	}

	if scanner, ok := dest.(Scanner); ok {
	return scanner.Scan(src)
	}

	dpv := reflect.ValueOf(dest)
	if dpv.Kind() != reflect.Ptr {
	return errors.New("destination not a pointer")
	}
	if dpv.IsNil() {
	return errNilPtr
	}

	if !sv.IsValid() {
	sv = reflect.ValueOf(src)
	}

	dv := reflect.Indirect(dpv)
	if sv.IsValid() && sv.Type().AssignableTo(dv.Type()) {
	switch b := src.(type) {
	case []byte:
	dv.Set(reflect.ValueOf(cloneBytes(b)))
	default:
	dv.Set(sv)
	}
	return nil
	}

	if dv.Kind() == sv.Kind() && sv.Type().ConvertibleTo(dv.Type()) {
	dv.Set(sv.Convert(dv.Type()))
	return nil
	}

	switch dv.Kind() {
	case reflect.Ptr:
	if src == nil {
	dv.Set(reflect.Zero(dv.Type()))
	return nil
	} else {
	dv.Set(reflect.New(dv.Type().Elem()))
	return convertAssign(dv.Interface(), src)
	}
	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
	s := asString(src)
	i64, err := strconv.ParseInt(s, 10, dv.Type().Bits())
	if err != nil {
	err = strconvErr(err)
	return fmt.Errorf("converting driver.Value type %T (%q) to a %s: %v", src, s, dv.Kind(), err)
	}
	dv.SetInt(i64)
	return nil
	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
	s := asString(src)
	u64, err := strconv.ParseUint(s, 10, dv.Type().Bits())
	if err != nil {
	err = strconvErr(err)
	return fmt.Errorf("converting driver.Value type %T (%q) to a %s: %v", src, s, dv.Kind(), err)
	}
	dv.SetUint(u64)
	return nil
	case reflect.Float32, reflect.Float64:
	s := asString(src)
	f64, err := strconv.ParseFloat(s, dv.Type().Bits())
	if err != nil {
	err = strconvErr(err)
	return fmt.Errorf("converting driver.Value type %T (%q) to a %s: %v", src, s, dv.Kind(), err)
	}
	dv.SetFloat(f64)
	return nil
	}

	return fmt.Errorf("unsupported Scan, storing driver.Value type %T into type %T", src, dest)
	}

	func strconvErr(err error) error {
	if ne, ok := err.(*strconv.NumError); ok {
	return ne.Err
	}
	return err
	}

	func cloneBytes(b []byte) []byte {
	if b == nil {
	return nil
	} else {
	c := make([]byte, len(b))
	copy(c, b)
	return c
	}
	}

	func asString(src interface{}) string {
	switch v := src.(type) {
	case string:
	return v
	case []byte:
	return string(v)
	}
	rv := reflect.ValueOf(src)
	switch rv.Kind() {
	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
	return strconv.FormatInt(rv.Int(), 10)
	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
	return strconv.FormatUint(rv.Uint(), 10)
	case reflect.Float64:
	return strconv.FormatFloat(rv.Float(), 'g', -1, 64)
	case reflect.Float32:
	return strconv.FormatFloat(rv.Float(), 'g', -1, 32)
	case reflect.Bool:
	return strconv.FormatBool(rv.Bool())
	}
	return fmt.Sprintf("%v", src)
	}

	func asBytes(buf []byte, rv reflect.Value) (b []byte, ok bool) {
	switch rv.Kind() {
	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
	return strconv.AppendInt(buf, rv.Int(), 10), true
	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
	return strconv.AppendUint(buf, rv.Uint(), 10), true
	case reflect.Float32:
	return strconv.AppendFloat(buf, rv.Float(), 'g', -1, 32), true
	case reflect.Float64:
	return strconv.AppendFloat(buf, rv.Float(), 'g', -1, 64), true
	case reflect.Bool:
	return strconv.AppendBool(buf, rv.Bool()), true
	case reflect.String:
	s := rv.String()
	return append(buf, s...), true
	}
	return
	}

	var valuerReflectType = reflect.TypeOf((*driver.Valuer)(nil)).Elem()

	// callValuerValue returns vr.Value(), with one exception:
	// If vr.Value is an auto-generated method on a pointer type and the
	// pointer is nil, it would panic at runtime in the panicwrap
	// method. Treat it like nil instead.
	// Issue 8415.
	//
	// This is so people can implement driver.Value on value types and
	// still use nil pointers to those types to mean nil/NULL, just like
	// string/*string.
	//
	// This function is mirrored in the database/sql/driver package.
	func callValuerValue(vr driver.Valuer) (v driver.Value, err error) {
	if rv := reflect.ValueOf(vr); rv.Kind() == reflect.Ptr &&
	rv.IsNil() &&
	rv.Type().Elem().Implements(valuerReflectType) {
	return nil, nil
	}
	return vr.Value()
	}