storj.io/minio@v0.0.0-20230509071714-0cbc90f649b1/pkg/s3select/csv/record.go (about)

     1  /*
     2   * MinIO Cloud Storage, (C) 2019 MinIO, Inc.
     3   *
     4   * Licensed under the Apache License, Version 2.0 (the "License");
     5   * you may not use this file except in compliance with the License.
     6   * You may obtain a copy of the License at
     7   *
     8   *     http://www.apache.org/licenses/LICENSE-2.0
     9   *
    10   * Unless required by applicable law or agreed to in writing, software
    11   * distributed under the License is distributed on an "AS IS" BASIS,
    12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13   * See the License for the specific language governing permissions and
    14   * limitations under the License.
    15   */
    16  
    17  package csv
    18  
    19  import (
    20  	"encoding/json"
    21  	"errors"
    22  	"fmt"
    23  	"io"
    24  
    25  	"github.com/bcicen/jstream"
    26  
    27  	csv "storj.io/minio/pkg/csvparser"
    28  	"storj.io/minio/pkg/s3select/sql"
    29  )
    30  
    31  // Record - is a CSV record.
    32  type Record struct {
    33  	columnNames  []string
    34  	csvRecord    []string
    35  	nameIndexMap map[string]int64
    36  }
    37  
    38  // Get - gets the value for a column name. CSV fields do not have any
    39  // defined type (other than the default string). So this function
    40  // always returns fields using sql.FromBytes so that the type
    41  // specified/implied by the query can be used, or can be automatically
    42  // converted based on the query.
    43  func (r *Record) Get(name string) (*sql.Value, error) {
    44  	index, found := r.nameIndexMap[name]
    45  	if !found {
    46  		return nil, fmt.Errorf("column %v not found", name)
    47  	}
    48  
    49  	if index >= int64(len(r.csvRecord)) {
    50  		// No value found for column 'name', hence return null
    51  		// value
    52  		return sql.FromNull(), nil
    53  	}
    54  
    55  	return sql.FromBytes([]byte(r.csvRecord[index])), nil
    56  }
    57  
    58  // Set - sets the value for a column name.
    59  func (r *Record) Set(name string, value *sql.Value) (sql.Record, error) {
    60  	r.columnNames = append(r.columnNames, name)
    61  	r.csvRecord = append(r.csvRecord, value.CSVString())
    62  	return r, nil
    63  }
    64  
    65  // Reset data in record.
    66  func (r *Record) Reset() {
    67  	if len(r.columnNames) > 0 {
    68  		r.columnNames = r.columnNames[:0]
    69  	}
    70  	if len(r.csvRecord) > 0 {
    71  		r.csvRecord = r.csvRecord[:0]
    72  	}
    73  	for k := range r.nameIndexMap {
    74  		delete(r.nameIndexMap, k)
    75  	}
    76  }
    77  
    78  // Clone the record.
    79  func (r *Record) Clone(dst sql.Record) sql.Record {
    80  	other, ok := dst.(*Record)
    81  	if !ok {
    82  		other = &Record{}
    83  	}
    84  	if len(other.columnNames) > 0 {
    85  		other.columnNames = other.columnNames[:0]
    86  	}
    87  	if len(other.csvRecord) > 0 {
    88  		other.csvRecord = other.csvRecord[:0]
    89  	}
    90  	other.columnNames = append(other.columnNames, r.columnNames...)
    91  	other.csvRecord = append(other.csvRecord, r.csvRecord...)
    92  	return other
    93  }
    94  
    95  // WriteCSV - encodes to CSV data.
    96  func (r *Record) WriteCSV(writer io.Writer, opts sql.WriteCSVOpts) error {
    97  	w := csv.NewWriter(writer)
    98  	w.Comma = opts.FieldDelimiter
    99  	w.AlwaysQuote = opts.AlwaysQuote
   100  	w.Quote = opts.Quote
   101  	w.QuoteEscape = opts.QuoteEscape
   102  	if err := w.Write(r.csvRecord); err != nil {
   103  		return err
   104  	}
   105  	w.Flush()
   106  	if err := w.Error(); err != nil {
   107  		return err
   108  	}
   109  
   110  	return nil
   111  }
   112  
   113  // WriteJSON - encodes to JSON data.
   114  func (r *Record) WriteJSON(writer io.Writer) error {
   115  	var kvs jstream.KVS = make([]jstream.KV, len(r.columnNames))
   116  	for i := 0; i < len(r.columnNames); i++ {
   117  		kvs[i] = jstream.KV{Key: r.columnNames[i], Value: r.csvRecord[i]}
   118  	}
   119  	return json.NewEncoder(writer).Encode(kvs)
   120  }
   121  
   122  // Raw - returns the underlying data with format info.
   123  func (r *Record) Raw() (sql.SelectObjectFormat, interface{}) {
   124  	return sql.SelectFmtCSV, r
   125  }
   126  
   127  // Replace - is not supported for CSV
   128  func (r *Record) Replace(_ interface{}) error {
   129  	return errors.New("Replace is not supported for CSV")
   130  }
   131  
   132  // NewRecord - creates new CSV record.
   133  func NewRecord() *Record {
   134  	return &Record{}
   135  }