// private interface to generate a list of interfaces from a given struct
// type, given a list of names to pull out of the struct. Used by public
// BindStruct interface.
func bindArgs(names []string, arg interface{}, m *reflectx.Mapper) ([]interface{}, error) {
arglist := make([]interface{}, 0, len(names))
// grab the indirected value of arg
v := reflect.ValueOf(arg)
for v = reflect.ValueOf(arg); v.Kind() == reflect.Ptr; {
v = v.Elem()
}
fields := m.TraversalsByName(v.Type(), names)
for i, t := range fields {
if len(t) == 0 {
return arglist, fmt.Errorf("could not find name %s in %#v", names[i], arg)
}
val := reflectx.FieldByIndexesReadOnly(v, t)
arglist = append(arglist, val.Interface())
}
return arglist, nil
}
// 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()
}