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minio/pkg/s3select/json/reader.go

79 lines
1.9 KiB

/*
* 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 (
"io"
"github.com/minio/minio/pkg/s3select/sql"
"github.com/bcicen/jstream"
)
// 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 kvs jstream.KVS
if v.ValueType == jstream.Object {
// This is a JSON object type (that preserves key
// order)
kvs = v.Value.(jstream.KVS)
} 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.
kvs = jstream.KVS{jstream.KV{Key: "_1", Value: v.Value}}
}
return &Record{
KVS: kvs,
SelectFormat: sql.SelectFmtJSON,
}, 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).ObjectAsKVS()
return &Reader{
args: args,
decoder: d,
valueCh: d.Stream(),
readCloser: readCloser,
}
}