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minio/pkg/s3select/csv/record.go

100 lines
2.5 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 (
"bytes"
"encoding/csv"
"fmt"
"github.com/minio/minio/pkg/s3select/sql"
"github.com/tidwall/sjson"
)
// Record - is 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
}
// MarshalCSV - encodes to CSV data.
func (r *Record) MarshalCSV(fieldDelimiter rune) ([]byte, error) {
buf := new(bytes.Buffer)
w := csv.NewWriter(buf)
w.Comma = fieldDelimiter
if err := w.Write(r.csvRecord); err != nil {
return nil, err
}
w.Flush()
if err := w.Error(); err != nil {
return nil, err
}
data := buf.Bytes()
return data[:len(data)-1], nil
}
// MarshalJSON - encodes to JSON data.
func (r *Record) MarshalJSON() ([]byte, error) {
data := "{}"
var err error
for i := len(r.columnNames) - 1; i >= 0; i-- {
if i >= len(r.csvRecord) {
continue
}
if data, err = sjson.Set(data, r.columnNames[i], r.csvRecord[i]); err != nil {
return nil, err
}
}
return []byte(data), nil
}
// NewRecord - creates new CSV record.
func NewRecord() *Record {
return &Record{}
}