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stream.go
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stream.go
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// Copyright 2020 the go-etl Authors.
//
// 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/csv"
"io"
"os"
"strconv"
"time"
"github.com/Breeze0806/go-etl/config"
"github.com/Breeze0806/go-etl/element"
"github.com/Breeze0806/go-etl/storage/stream/file"
"github.com/Breeze0806/go-etl/storage/stream/file/compress"
"github.com/pingcap/errors"
)
func init() {
var opener Opener
file.RegisterOpener("csv", &opener)
var creator Creator
file.RegisterCreator("csv", &creator)
}
//Opener csv输入流打开器
type Opener struct {
}
//Open 打开一个名为filename的csv输入流
func (o *Opener) Open(filename string) (file.InStream, error) {
return NewInStream(filename)
}
//Creator csv输出流创建器
type Creator struct {
}
//Create 创建一个名为filename的csv输出流
func (c *Creator) Create(filename string) (file.OutStream, error) {
return NewOutStream(filename)
}
//Stream csv文件流
type Stream struct {
file *os.File
}
//NewInStream 创建一个名为filename的csv输入流
func NewInStream(filename string) (file.InStream, error) {
stream := &Stream{}
var err error
stream.file, err = os.Open(filename)
if err != nil {
return nil, err
}
return stream, nil
}
//NewOutStream 创建一个名为filename的csv输出流
func NewOutStream(filename string) (file.OutStream, error) {
stream := &Stream{}
var err error
stream.file, err = os.Create(filename)
if err != nil {
return nil, err
}
return stream, nil
}
//Writer 新建一个配置未conf的csv流写入器
func (s *Stream) Writer(conf *config.JSON) (file.StreamWriter, error) {
return NewWriter(s.file, conf)
}
//Rows 新建一个配置未conf的csv行读取器
func (s *Stream) Rows(conf *config.JSON) (rows file.Rows, err error) {
return NewRows(s.file, conf)
}
//Close 关闭文件流
func (s *Stream) Close() (err error) {
return s.file.Close()
}
//Rows 行读取器
type Rows struct {
columns map[int]Column
rc io.ReadCloser
reader *csv.Reader
record []string
conf *InConfig
row int
err error
}
//NewRows 通过文件句柄f,和配置文件c 创建行读取器
func NewRows(f *os.File, c *config.JSON) (file.Rows, error) {
var conf *InConfig
var err error
if conf, err = NewInConfig(c); err != nil {
return nil, err
}
rows := &Rows{
columns: make(map[int]Column),
conf: conf,
}
if rows.rc, err = compress.Type(conf.Compress).ReadCloser(f); err != nil {
return nil, err
}
rows.reader = csv.NewReader(f)
rows.reader.Comma = conf.comma()
rows.reader.Comment = conf.comment()
for _, v := range conf.Columns {
rows.columns[v.index()] = v
}
return rows, nil
}
// Next 是否有下一行
func (r *Rows) Next() bool {
if r.record, r.err = r.reader.Read(); r.err != nil {
if r.err == io.EOF {
r.err = nil
}
return false
}
return true
}
// Scan 扫描成列
func (r *Rows) Scan() (columns []element.Column, err error) {
r.row++
if r.row < r.conf.startRow() {
return nil, nil
}
for i, v := range r.record {
var c element.Column
c, err = r.getColum(i, v)
if err != nil {
return nil, err
}
columns = append(columns, c)
}
return
}
// Error 读取中的错误
func (r *Rows) Error() error {
return r.err
}
// Close 关闭读文件流
func (r *Rows) Close() error {
return r.rc.Close()
}
func (r *Rows) getColum(index int, s string) (element.Column, error) {
c, ok := r.columns[index]
if ok && element.ColumnType(c.Type) == element.TypeTime {
if s == r.conf.NullFormat {
return element.NewDefaultColumn(element.NewNilTimeColumnValue(),
strconv.Itoa(index), 0), nil
}
layout := c.layout()
t, err := time.Parse(layout, s)
if err != nil {
return nil, errors.Wrapf(err, "Parse time fail. layout: %v", layout)
}
return element.NewDefaultColumn(element.NewTimeColumnValueWithDecoder(t,
element.NewStringTimeDecoder(layout)),
strconv.Itoa(index), 0), nil
}
if s == r.conf.NullFormat {
return element.NewDefaultColumn(element.NewNilStringColumnValue(),
strconv.Itoa(index), 0), nil
}
decodeFunc := decoders[r.conf.encoding()]
s, err := decodeFunc(s)
if err != nil {
return nil, err
}
return element.NewDefaultColumn(element.NewStringColumnValue(s), strconv.Itoa(index), 0), nil
}
//Writer csv流写入器
type Writer struct {
writer *csv.Writer
wc io.WriteCloser
columns map[int]Column
conf *OutConfig
}
//NewWriter 通过文件句柄f,和配置文件c 创建csv流写入器
func NewWriter(f *os.File, c *config.JSON) (file.StreamWriter, error) {
var conf *OutConfig
var err error
if conf, err = NewOutConfig(c); err != nil {
return nil, err
}
w := &Writer{
columns: make(map[int]Column),
conf: conf,
}
if w.wc, err = compress.Type(conf.Compress).WriteCloser(f); err != nil {
return nil, err
}
w.writer = csv.NewWriter(w.wc)
w.writer.Comma = conf.comma()
for _, v := range conf.Columns {
w.columns[v.index()] = v
}
return w, nil
}
//Flush 刷新至磁盘
func (w *Writer) Flush() (err error) {
w.writer.Flush()
return
}
//Close 关闭
func (w *Writer) Close() (err error) {
w.writer.Flush()
return w.wc.Close()
}
//Write 将记录record 写入csv文件
func (w *Writer) Write(record element.Record) (err error) {
if w.conf.HasHeader {
if len(w.conf.Header) == 0 {
for i := 0; i < record.ColumnNumber(); i++ {
var col element.Column
if col, err = record.GetByIndex(i); err != nil {
return
}
w.conf.Header = append(w.conf.Header, col.Name())
}
}
if err = w.writer.Write(w.conf.Header); err != nil {
return err
}
w.conf.HasHeader = false
}
var records []string
for i := 0; i < record.ColumnNumber(); i++ {
var col element.Column
if col, err = record.GetByIndex(i); err != nil {
return
}
var s string
if s, err = w.getRecord(col, i); err != nil {
return
}
records = append(records, s)
}
return w.writer.Write(records)
}
func (w *Writer) getRecord(col element.Column, i int) (s string, err error) {
if col.IsNil() {
return w.conf.NullFormat, nil
}
if c, ok := w.columns[i]; ok && element.ColumnType(c.Type) == element.TypeTime {
var t time.Time
if t, err = col.AsTime(); err != nil {
return
}
s = t.Format(c.layout())
return
}
s, err = col.AsString()
if err != nil {
return "", err
}
encodeFunc := encoders[w.conf.encoding()]
s, err = encodeFunc(s)
if err != nil {
return "", err
}
return
}