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minio/pkg/s3select/csv/record.go

131 lines
3.4 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 csv
import (
"encoding/json"
"errors"
"fmt"
"io"
"github.com/bcicen/jstream"
csv "github.com/minio/minio/pkg/csvparser"
"github.com/minio/minio/pkg/s3select/sql"
)
// Record - is a CSV record.
type Record struct {
columnNames []string
csvRecord []string
nameIndexMap map[string]int64
}
// Get - gets the value for a column name. CSV fields do not have any
// defined type (other than the default string). So this function
// always returns fields using sql.FromBytes so that the type
// specified/implied by the query can be used, or can be automatically
// converted based on the query.
func (r *Record) Get(name string) (*sql.Value, error) {
index, found := r.nameIndexMap[name]
if !found {
return nil, fmt.Errorf("column %v not found", name)
}
if index >= int64(len(r.csvRecord)) {
// No value found for column 'name', hence return null
// value
return sql.FromNull(), nil
}
return sql.FromBytes([]byte(r.csvRecord[index])), nil
}
// Set - sets the value for a column name.
func (r *Record) Set(name string, value *sql.Value) error {
r.columnNames = append(r.columnNames, name)
r.csvRecord = append(r.csvRecord, value.CSVString())
return nil
}
// Reset data in record.
func (r *Record) Reset() {
if len(r.columnNames) > 0 {
r.columnNames = r.columnNames[:0]
}
if len(r.csvRecord) > 0 {
r.csvRecord = r.csvRecord[:0]
}
for k := range r.nameIndexMap {
delete(r.nameIndexMap, k)
}
}
// Clone the record.
func (r *Record) Clone(dst sql.Record) sql.Record {
other, ok := dst.(*Record)
if !ok {
other = &Record{}
}
if len(other.columnNames) > 0 {
other.columnNames = other.columnNames[:0]
}
if len(other.csvRecord) > 0 {
other.csvRecord = other.csvRecord[:0]
}
other.columnNames = append(other.columnNames, r.columnNames...)
other.csvRecord = append(other.csvRecord, r.csvRecord...)
return other
}
// WriteCSV - encodes to CSV data.
func (r *Record) WriteCSV(writer io.Writer, fieldDelimiter rune) error {
w := csv.NewWriter(writer)
w.Comma = fieldDelimiter
if err := w.Write(r.csvRecord); err != nil {
return err
}
w.Flush()
if err := w.Error(); err != nil {
return err
}
return nil
}
// WriteJSON - encodes to JSON data.
func (r *Record) WriteJSON(writer io.Writer) error {
var kvs jstream.KVS = make([]jstream.KV, len(r.columnNames))
for i := 0; i < len(r.columnNames); i++ {
kvs[i] = jstream.KV{Key: r.columnNames[i], Value: r.csvRecord[i]}
}
return json.NewEncoder(writer).Encode(kvs)
}
// Raw - returns the underlying data with format info.
func (r *Record) Raw() (sql.SelectObjectFormat, interface{}) {
return sql.SelectFmtCSV, r
}
// Replace - is not supported for CSV
func (r *Record) Replace(_ jstream.KVS) error {
return errors.New("Replace is not supported for CSV")
}
// NewRecord - creates new CSV record.
func NewRecord() *Record {
return &Record{}
}