github.com/dayvar14/tail@v0.0.0-20240222011302-f530c4fa0c9f/examples/03-consumeJSON/main.go (about)

     1  // Consume and unmarshall JSON.
     2  //
     3  // In this example JSON lines are added by createJSON in a tight loop.
     4  // Each line is unmarshalled and a field printed.
     5  // Exit with Ctrl+C.
     6  package main
     7  
     8  import (
     9  	"encoding/json"
    10  	"fmt"
    11  	"io/ioutil"
    12  	"os"
    13  	"strconv"
    14  	
    15  	"github.com/nxadm/tail"
    16  )
    17  
    18  type jsonStruct struct {
    19  	Counter string `json:"counter"`
    20  }
    21  
    22  func main() {
    23  	file, err := ioutil.TempFile(os.TempDir(), "")
    24  	if err != nil {
    25  		panic(err)
    26  	}
    27  	fmt.Println(file.Name())
    28  	defer file.Close()
    29  	defer os.Remove(file.Name())
    30  
    31  	t, err := tail.TailFile(file.Name(), tail.Config{Follow: true})
    32  	if err != nil {
    33  		panic(err)
    34  	}
    35  
    36  	go createJSON(file)
    37  	var js jsonStruct
    38  	for line := range t.Lines {
    39  		fmt.Printf("JSON: " + line.Text + "\n")
    40  
    41  		err := json.Unmarshal([]byte(line.Text), &js)
    42  		if err != nil {
    43  			panic(err)
    44  		}
    45  		fmt.Printf("JSON counter field: " + js.Counter + "\n")
    46  	}
    47  }
    48  
    49  func createJSON(file *os.File) {
    50  	var counter int
    51  	for {
    52  		file.WriteString("{ \"counter\": \"" + strconv.Itoa(counter) + "\"}\n")
    53  		counter++
    54  	}
    55  }