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|
package sqlx
import (
"bytes"
"errors"
"reflect"
"strconv"
"strings"
"github.com/jmoiron/sqlx/reflectx"
)
// Bindvar types supported by Rebind, BindMap and BindStruct.
const (
UNKNOWN = iota
QUESTION
DOLLAR
NAMED
)
// BindType returns the bindtype for a given database given a drivername.
func BindType(driverName string) int {
switch driverName {
case "postgres", "pgx":
return DOLLAR
case "mysql":
return QUESTION
case "sqlite3":
return QUESTION
case "oci8", "ora", "goracle":
return NAMED
}
return UNKNOWN
}
// FIXME: this should be able to be tolerant of escaped ?'s in queries without
// losing much speed, and should be to avoid confusion.
// Rebind a query from the default bindtype (QUESTION) to the target bindtype.
func Rebind(bindType int, query string) string {
switch bindType {
case QUESTION, UNKNOWN:
return query
}
qb := []byte(query)
// Add space enough for 10 params before we have to allocate
rqb := make([]byte, 0, len(qb)+10)
j := 1
for _, b := range qb {
if b == '?' {
switch bindType {
case DOLLAR:
rqb = append(rqb, '$')
case NAMED:
rqb = append(rqb, ':', 'a', 'r', 'g')
}
for _, b := range strconv.Itoa(j) {
rqb = append(rqb, byte(b))
}
j++
} else {
rqb = append(rqb, b)
}
}
return string(rqb)
}
// Experimental implementation of Rebind which uses a bytes.Buffer. The code is
// much simpler and should be more resistant to odd unicode, but it is twice as
// slow. Kept here for benchmarking purposes and to possibly replace Rebind if
// problems arise with its somewhat naive handling of unicode.
func rebindBuff(bindType int, query string) string {
if bindType != DOLLAR {
return query
}
b := make([]byte, 0, len(query))
rqb := bytes.NewBuffer(b)
j := 1
for _, r := range query {
if r == '?' {
rqb.WriteRune('$')
rqb.WriteString(strconv.Itoa(j))
j++
} else {
rqb.WriteRune(r)
}
}
return rqb.String()
}
// In expands slice values in args, returning the modified query string
// and a new arg list that can be executed by a database. The `query` should
// use the `?` bindVar. The return value uses the `?` bindVar.
func In(query string, args ...interface{}) (string, []interface{}, error) {
// argMeta stores reflect.Value and length for slices and
// the value itself for non-slice arguments
type argMeta struct {
v reflect.Value
i interface{}
length int
}
var flatArgsCount int
var anySlices bool
meta := make([]argMeta, len(args))
for i, arg := range args {
v := reflect.ValueOf(arg)
t := reflectx.Deref(v.Type())
if t.Kind() == reflect.Slice {
meta[i].length = v.Len()
meta[i].v = v
anySlices = true
flatArgsCount += meta[i].length
if meta[i].length == 0 {
return "", nil, errors.New("empty slice passed to 'in' query")
}
} else {
meta[i].i = arg
flatArgsCount++
}
}
// don't do any parsing if there aren't any slices; note that this means
// some errors that we might have caught below will not be returned.
if !anySlices {
return query, args, nil
}
newArgs := make([]interface{}, 0, flatArgsCount)
var arg, offset int
var buf bytes.Buffer
for i := strings.IndexByte(query[offset:], '?'); i != -1; i = strings.IndexByte(query[offset:], '?') {
if arg >= len(meta) {
// if an argument wasn't passed, lets return an error; this is
// not actually how database/sql Exec/Query works, but since we are
// creating an argument list programmatically, we want to be able
// to catch these programmer errors earlier.
return "", nil, errors.New("number of bindVars exceeds arguments")
}
argMeta := meta[arg]
arg++
// not a slice, continue.
// our questionmark will either be written before the next expansion
// of a slice or after the loop when writing the rest of the query
if argMeta.length == 0 {
offset = offset + i + 1
newArgs = append(newArgs, argMeta.i)
continue
}
// write everything up to and including our ? character
buf.WriteString(query[:offset+i+1])
newArgs = append(newArgs, argMeta.v.Index(0).Interface())
for si := 1; si < argMeta.length; si++ {
buf.WriteString(", ?")
newArgs = append(newArgs, argMeta.v.Index(si).Interface())
}
// slice the query and reset the offset. this avoids some bookkeeping for
// the write after the loop
query = query[offset+i+1:]
offset = 0
}
buf.WriteString(query)
if arg < len(meta) {
return "", nil, errors.New("number of bindVars less than number arguments")
}
return buf.String(), newArgs, nil
}
|
