minio/pkg/s3select/json/reader.go

82 lines
1.9 KiB
Go

/*
* Minio Cloud Storage, (C) 2019 Minio, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package json
import (
"encoding/json"
"io"
"github.com/minio/minio/pkg/s3select/sql"
"github.com/bcicen/jstream"
"github.com/tidwall/sjson"
)
// Reader - JSON record reader for S3Select.
type Reader struct {
args *ReaderArgs
decoder *jstream.Decoder
valueCh chan *jstream.MetaValue
readCloser io.ReadCloser
}
// Read - reads single record.
func (r *Reader) Read() (sql.Record, error) {
v, ok := <-r.valueCh
if !ok {
if err := r.decoder.Err(); err != nil {
return nil, errJSONParsingError(err)
}
return nil, io.EOF
}
var data []byte
var err error
if v.ValueType == jstream.Object {
data, err = json.Marshal(v.Value)
} else {
// To be AWS S3 compatible
// Select for JSON needs to output non-object JSON as single column value
// i.e. a map with `_1` as key and value as the non-object.
data, err = sjson.SetBytes(data, "_1", v.Value)
}
if err != nil {
return nil, errJSONParsingError(err)
}
return &Record{
data: data,
}, nil
}
// Close - closes underlaying reader.
func (r *Reader) Close() error {
return r.readCloser.Close()
}
// NewReader - creates new JSON reader using readCloser.
func NewReader(readCloser io.ReadCloser, args *ReaderArgs) *Reader {
d := jstream.NewDecoder(readCloser, 0)
return &Reader{
args: args,
decoder: d,
valueCh: d.Stream(),
readCloser: readCloser,
}
}