Convert log File Data to Json Object in Vue client

I have a log file as follow:

{"L":"DEBUG","T":"2021-11-01T17:37:54.167+0530","M":"Route.go:74[IN : GetLatestLogs]"}
{"L":"DEBUG","T":"2021-11-01T17:37:54.167+0530","M":"Service.go:40[IN : GetRecentServerErrorLogService]"}
{"L":"DEBUG","T":"2021-11-01T17:37:54.167+0530","M":"DAO.go:117[IN : GetRecentServerErrorLogDAO]"}
{"L":"DEBUG","T":"2021-11-01T17:37:54.168+0530","M":"DAO.go:148[OUT : GetRecentServerErrorLogDAO]"}
{"L":"DEBUG","T":"2021-11-01T17:37:54.168+0530","M":"Service.go:47[OUT : GetRecentServerErrorLogService]"}
{"L":"DEBUG","T":"2021-11-01T17:37:54.168+0530","M":"Route.go:79[OUT : GetLatestLogs]"}
{"L":"DEBUG","T":"2021-11-01T17:40:55.331+0530","M":"Route.go:74[IN : GetLatestLogs]"}

I am reading this file in the Golang echo server as follow:

file, err := os.Open(logFilePath)

stat, _ := os.Stat(logFilePath)
buf := make([]byte, stat.Size())
_, err = file.Read(buf)
serverLog := string(buf)

and return this string generated back

return c.JSON(http.StatusOK, serverLog)

this is what I get as result

"{\"L\":\"DEBUG\",\"T\":\"2021-11-01T17:37:54.167+0530\",\"M\":\"Route.go:74[IN : GetLatestLogs]\"}\n{\"L\":\"DEBUG\",\"T\":\"2021-11-01T17:37:54.167+0530\",\"M\":\"Service.go:40[IN : GetRecentServerErrorLogService]\"}\n{\"L\":\"DEBUG\",\"T\":\"2021-11-01T17:37:54.167+0530\",\"M\":\"DAO.go:117[IN : GetRecentServerErrorLogDAO]\"}\n{\"L\":\"DEBUG\",\"T\":\"2021-11-01T17:37:54.168+0530\",\"M\":\"DAO.go:148[OUT : GetRecentServerErrorLogDAO]\"}\n{\"L\":\"DEBUG\",\"T\":\"2021-11-01T17:37:54.168+0530\",\"M\":\"Service.go:47[OUT : GetRecentServerErrorLogService]\"}\n{\"L\":\"DEBUG\",\"T\":\"2021-11-01T17:37:54.168+0530\",\"M\":\"Route.go:79[OUT : GetLatestLogs]\"}\n{\"L\":\"DEBUG\",\"T\":\"2021-11-01T17:40:55.331+0530\",\"M\":\"Route.go:74[IN : GetLatestLogs]\"}{\"L\":\"DEBUG\",\"T\":\"2021-11-02T09:48:49.982+0530\",\"M\":\"controlPanelRoute.go:74[IN : GetLatestLogs]\"}\n{\"L\":\"DEBUG\",\"T\":\"2021-11-02T09:48:49.982+0530\",\"M\":\"controlPanelService.go:40[IN : GetRecentServerErrorLogService]\"}\n{\"L\":\"DEBUG\",\"T\":\"2021-11-02T09:48:49.982+0530\",\"M\":\"controlPanelDAO.go:117[IN : GetRecentServerErrorLogDAO]\"}\n"

I want to convert this received response to a JSON object.

This is my desired output:

[
    {
        "L": "DEBUG",
        "T": "2021-11-01T17:37:54.167+0530",
        "M": "Route.go:74[IN : GetLatestLogs]"
    },
    {
        "L": "DEBUG",
        "T": "2021-11-01T17:37:54.167+0530",
        "M": "Service.go:40[IN : GetRecentServerErrorLogService]"
    },
    {
        "L": "DEBUG",
        "T": "2021-11-01T17:37:54.167+0530",
        "M": "DAO.go:117[IN : GetRecentServerErrorLogDAO]"
    },
    {
        "L": "DEBUG",
        "T": "2021-11-01T17:37:54.168+0530",
        "M": "DAO.go:148[OUT : GetRecentServerErrorLogDAO]"
    },
    {
        "L": "DEBUG",
        "T": "2021-11-01T17:37:54.168+0530",
        "M": "Service.go:47[OUT : GetRecentServerErrorLogService]"
    },
    {
        "L": "DEBUG",
        "T": "2021-11-01T17:37:54.168+0530",
        "M": "Route.go:79[OUT : GetLatestLogs]"
    },
    {
        "L": "DEBUG",
        "T": "2021-11-01T17:40:55.331+0530",
        "M": "Route.go:74[IN : GetLatestLogs]"
    }
]

That looks like one valid Json statement after another. You can open the file, create a decoder with json.NewDecoder(filehandle), and read one Json statement out if it after another. Heres' an example with the input hard coded:

package main

import (
	"fmt"
	"bytes"
	"io"
	"encoding/json"
)

var input =[]byte( `{"L":"DEBUG","T":"2021-11-01T17:37:54.167+0530","M":"Route.go:74[IN : GetLatestLogs]"}
{"L":"DEBUG","T":"2021-11-01T17:37:54.167+0530","M":"Service.go:40[IN : GetRecentServerErrorLogService]"}
{"L":"DEBUG","T":"2021-11-01T17:37:54.167+0530","M":"DAO.go:117[IN : GetRecentServerErrorLogDAO]"}
{"L":"DEBUG","T":"2021-11-01T17:37:54.168+0530","M":"DAO.go:148[OUT : GetRecentServerErrorLogDAO]"}
{"L":"DEBUG","T":"2021-11-01T17:37:54.168+0530","M":"Service.go:47[OUT : GetRecentServerErrorLogService]"}
{"L":"DEBUG","T":"2021-11-01T17:37:54.168+0530","M":"Route.go:79[OUT : GetLatestLogs]"}
{"L":"DEBUG","T":"2021-11-01T17:40:55.331+0530","M":"Route.go:74[IN : GetLatestLogs]"}`)

func main() {
	r := json.NewDecoder(bytes.NewBuffer(input))
	var data interface{}
	for i := 0;;i++{
		if err := r.Decode(&data); err != nil {
			if err == io.EOF {
				break
			}
			panic(err)
		} else {
			fmt.Printf("%d: %+v\n", i, data)
		}
	}
}

Output should be:

0: map[L:DEBUG M:Route.go:74[IN : GetLatestLogs] T:2021-11-01T17:37:54.167+0530]
1: map[L:DEBUG M:Service.go:40[IN : GetRecentServerErrorLogService] T:2021-11-01T17:37:54.167+0530]
2: map[L:DEBUG M:DAO.go:117[IN : GetRecentServerErrorLogDAO] T:2021-11-01T17:37:54.167+0530]
3: map[L:DEBUG M:DAO.go:148[OUT : GetRecentServerErrorLogDAO] T:2021-11-01T17:37:54.168+0530]
4: map[L:DEBUG M:Service.go:47[OUT : GetRecentServerErrorLogService] T:2021-11-01T17:37:54.168+0530]
5: map[L:DEBUG M:Route.go:79[OUT : GetLatestLogs] T:2021-11-01T17:37:54.168+0530]
6: map[L:DEBUG M:Route.go:74[IN : GetLatestLogs] T:2021-11-01T17:40:55.331+0530]

As you can see, Decode() stops at the end of a Json expression, so you can just keep reading over and over again.

file, err := os.Open("/log/file/path")
if err != nil {
	panic(err)
}
info, err := file.Stat()
if err != nil {
	panic(err)
}

logs := make(json.RawMessage, 1, info.Size()+1) // len=1 for '['
dec := json.NewDecoder(file)
for dec.More() {
	var log json.RawMessage
	if err := dec.Decode(&log); err != nil {
		panic(err)
	}

	logs = append(logs, log...)
	logs = append(logs, ',')
}
if n := len(logs); n > 1 {
	logs[0], logs[n-1] = '[', ']'
	c.JSON(http.StatusOK, logs)
}

From your code it seems you depend on Gin to do the conversion for you:

return c.JSON(http.StatusOK, serverLog)

You can actually handle it yourself, but it may require Unmarshalling line by line, since the log text file isn't a valid JSON array. Then I marshall the valid structure back into JSON. In the example below I used bufio to read the text file by line, and unmarshall to a Log struct:

package main

import (
	"os"
	"fmt"
	"encoding/json"
	"bufio"
)

type Log struct {
	L	string
	T	string
	M	string
}

func main() {
	f, err := os.Open("log.txt")
	defer f.Close()

	var logs []Log
	var log Log

	input := bufio.NewScanner(f)

	for input.Scan() {
		textByte := []byte(input.Text())
		err = json.Unmarshal(textByte, &log)
		if err != nil {
			fmt.Printf("Problems with unmarshalling: %v\n", err)
			os.Exit(1)
		}
		logs = append(logs, log)
	}

	data, err := json.MarshalIndent(logs, "", "    ")
	if err != nil {
		fmt.Printf("Error in marshalling: %v\n", err)
		os.Exit(1)
	}

	fmt.Printf("%s\n", data)
}

Or you can return the string from a function:

return fmt.Sprintf("%s\n", data)

Here's the output:

[
    {
        "L": "DEBUG",
        "T": "2021-11-01T17:37:54.167+0530",
        "M": "Route.go:74[IN : GetLatestLogs]"
    },
    {
        "L": "DEBUG",
        "T": "2021-11-01T17:37:54.167+0530",
        "M": "Service.go:40[IN : GetRecentServerErrorLogService]"
    },
    {
        "L": "DEBUG",
        "T": "2021-11-01T17:37:54.167+0530",
        "M": "DAO.go:117[IN : GetRecentServerErrorLogDAO]"
    },
    {
        "L": "DEBUG",
        "T": "2021-11-01T17:37:54.168+0530",
        "M": "DAO.go:148[OUT : GetRecentServerErrorLogDAO]"
    },
    {
        "L": "DEBUG",
        "T": "2021-11-01T17:37:54.168+0530",
        "M": "Service.go:47[OUT : GetRecentServerErrorLogService]"
    },
    {
        "L": "DEBUG",
        "T": "2021-11-01T17:37:54.168+0530",
        "M": "Route.go:79[OUT : GetLatestLogs]"
    },
    {
        "L": "DEBUG",
        "T": "2021-11-01T17:40:55.331+0530",
        "M": "Route.go:74[IN : GetLatestLogs]"
    }
]