Changelog 1.7.0 (#49)

* Add an example for metadata writing
* Fix CI (go 1.13 compatibility)
* Update README.MD

Author: barasher

README.MD

@@ -8,7 +8,7 @@
 
 **go-exiftool** is a golang library that wraps [ExifTool](https://www.sno.phy.queensu.ca/~phil/exiftool/).
 
-[ExifTool](https://www.sno.phy.queensu.ca/~phil/exiftool/)'s purpose is to extract as much metadata as possible (EXIF, IPTC, XMP, GPS, ...) from [a lots of differents file types](https://www.sno.phy.queensu.ca/~phil/exiftool/#supported) (Office documents, pictures, movies, PDF, ...).
+[ExifTool](https://www.sno.phy.queensu.ca/~phil/exiftool/)'s purpose is to extract and update as much metadata as possible (EXIF, IPTC, XMP, GPS, ...) from [a lots of differents file types](https://www.sno.phy.queensu.ca/~phil/exiftool/#supported) (Office documents, pictures, movies, PDF, ...).
 
 **go-exiftool** uses [ExifTool](https://www.sno.phy.queensu.ca/~phil/exiftool/)'s *`stay_open`* feature to [optimize performance](https://www.sno.phy.queensu.ca/~phil/exiftool/#performance).
 
@@ -22,6 +22,8 @@ By default, `go-exiftool` binary will look for `exiftool` binary in $PATH, but a
 
 ## Usage
 
+### Metadata extraction
+
 ```go
 et, err := exiftool.NewExiftool()
 if err != nil {
@@ -62,6 +64,10 @@ Output :
 (...)
 ```
 
+### Metadata update
+
+See [example function ExampleExiftool_Write in exiftool_sample_test.go](exiftool_sample_test.go)
+
 ## Changelog
 
 - v1.1.0 : initial release
@@ -87,4 +93,6 @@ Output :
 - [v1.6.1](https://github.com/barasher/go-exiftool/milestone/11)
   - "SetExiftoolBinaryPath" functional option : specify where to find exiftool binary (default : $path)
 - [v1.6.2](https://github.com/barasher/go-exiftool/milestone/12)
-  - Several improvements (thanks to [Dale Hui](https://github.com/dhui))
+  - Several improvements (thanks to [Dale Hui](https://github.com/dhui))
+- [v1.7.0](https://github.com/barasher/go-exiftool/milestone/13)
+  - Add metadata writing capabilities (thanks to [Dale Hui](https://github.com/dhui))

exiftool_sample_test.go

@@ -2,11 +2,16 @@ package exiftool_test
 
 import (
 	"fmt"
+	"io"
+	"os"
+
+	"io/ioutil"
+	"path/filepath"
 
 	"github.com/barasher/go-exiftool"
 )
 
-func ExampleExiftool() {
+func ExampleExiftool_Read() {
 	et, err := exiftool.NewExiftool()
 	if err != nil {
 		fmt.Printf("Error when intializing: %v\n", err)
@@ -27,3 +32,48 @@ func ExampleExiftool() {
 		}
 	}
 }
+
+func copyFile(src, dest string) (err error) {
+	s, err := os.Open(src)
+	if err != nil {
+		return err
+	}
+	defer s.Close()
+
+	d, err := os.Create(dest)
+	if err != nil {
+		return err
+	}
+	defer d.Close()
+
+	_, err = io.Copy(d, s)
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+func ExampleExiftool_Write() {
+	// error handling are skipped in this example
+
+	tmpDir, _ := ioutil.TempDir("", "ExampleExiftoolWrite")
+	testFile := filepath.Join(tmpDir, "20190404_131804.jpg")
+	copyFile("testdata/20190404_131804.jpg", testFile)
+
+	e, _ := exiftool.NewExiftool()
+	defer e.Close()
+	originals := e.ExtractMetadata(testFile)
+	title, _ := originals[0].GetString("Title")
+	fmt.Println("title:" + title)
+
+	originals[0].SetString("Title", "newTitle")
+	e.WriteMetadata(originals)
+
+	altered := e.ExtractMetadata(testFile)
+	title, _ = altered[0].GetString("Title")
+	fmt.Println("title:" + title)
+
+	// Output:
+	// title:
+	// title:newTitle
+}