func baseType(t reflect.Type, expected reflect.Kind) (reflect.Type, error) {
t = reflectx.Deref(t)
if t.Kind() != expected {
return nil, fmt.Errorf("expected %s but got %s", expected, t.Kind())
}
return t, nil
}
func (r *Row) scanAny(dest interface{}, structOnly bool) error {
if r.err != nil {
return r.err
}
defer r.rows.Close()
v := reflect.ValueOf(dest)
if v.Kind() != reflect.Ptr {
return errors.New("must pass a pointer, not a value, to StructScan destination")
}
if v.IsNil() {
return errors.New("nil pointer passed to StructScan destination")
}
base := reflectx.Deref(v.Type())
scannable := isScannable(base)
if structOnly && scannable {
return structOnlyError(base)
}
columns, err := r.Columns()
if err != nil {
return err
}
if scannable && len(columns) > 1 {
return fmt.Errorf("scannable dest type %s with >1 columns (%d) in result", base.Kind(), len(columns))
}
if scannable {
return r.Scan(dest)
}
m := r.Mapper
fields := m.TraversalsByName(v.Type(), columns)
// if we are not unsafe and are missing fields, return an error
if f, err := missingFields(fields); err != nil && !r.unsafe {
return fmt.Errorf("missing destination name %s", columns[f])
}
values := make([]interface{}, len(columns))
err = fieldsByTraversal(v, fields, values, true)
if err != nil {
return err
}
// scan into the struct field pointers and append to our results
return r.Scan(values...)
}
// scanAll scans all rows into a destination, which must be a slice of any
// type. If the destination slice type is a Struct, then StructScan will be
// used on each row. If the destination is some other kind of base type, then
// each row must only have one column which can scan into that type. This
// allows you to do something like:
//
// rows, _ := db.Query("select id from people;")
// var ids []int
// scanAll(rows, &ids, false)
//
// and ids will be a list of the id results. I realize that this is a desirable
// interface to expose to users, but for now it will only be exposed via changes
// to `Get` and `Select`. The reason that this has been implemented like this is
// this is the only way to not duplicate reflect work in the new API while
// maintaining backwards compatibility.
func scanAll(rows rowsi, dest interface{}, structOnly bool) error {
var v, vp reflect.Value
value := reflect.ValueOf(dest)
// json.Unmarshal returns errors for these
if value.Kind() != reflect.Ptr {
return errors.New("must pass a pointer, not a value, to StructScan destination")
}
if value.IsNil() {
return errors.New("nil pointer passed to StructScan destination")
}
direct := reflect.Indirect(value)
slice, err := baseType(value.Type(), reflect.Slice)
if err != nil {
return err
}
isPtr := slice.Elem().Kind() == reflect.Ptr
base := reflectx.Deref(slice.Elem())
scannable := isScannable(base)
if structOnly && scannable {
return structOnlyError(base)
}
columns, err := rows.Columns()
if err != nil {
return err
}
// if it's a base type make sure it only has 1 column; if not return an error
if scannable && len(columns) > 1 {
return fmt.Errorf("non-struct dest type %s with >1 columns (%d)", base.Kind(), len(columns))
}
if !scannable {
var values []interface{}
var m *reflectx.Mapper
switch rows.(type) {
case *Rows:
m = rows.(*Rows).Mapper
default:
m = mapper()
}
fields := m.TraversalsByName(base, columns)
// if we are not unsafe and are missing fields, return an error
if f, err := missingFields(fields); err != nil && !isUnsafe(rows) {
return fmt.Errorf("missing destination name %s", columns[f])
}
values = make([]interface{}, len(columns))
for rows.Next() {
// create a new struct type (which returns PtrTo) and indirect it
vp = reflect.New(base)
v = reflect.Indirect(vp)
err = fieldsByTraversal(v, fields, values, true)
// scan into the struct field pointers and append to our results
err = rows.Scan(values...)
if err != nil {
return err
}
if isPtr {
direct.Set(reflect.Append(direct, vp))
} else {
direct.Set(reflect.Append(direct, v))
}
}
} else {
for rows.Next() {
vp = reflect.New(base)
err = rows.Scan(vp.Interface())
// append
if isPtr {
direct.Set(reflect.Append(direct, vp))
} else {
direct.Set(reflect.Append(direct, reflect.Indirect(vp)))
}
}
}
return rows.Err()
}
// 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
}