golang format data to JSON format in one pass - json

Question

My original data format:
id=1, name=peter, age=12
I converted it to JSON string:
{"id" : "1", "name" : "peter", "age" : "12"}
I use the following golang statement to do the conversion:
Regex, err = regexp.Compile(`([^,\s]*)=([^,\s]*)`)
JSON := fmt.Sprintf("{%s}", Regex.ReplaceAllString(inp, `"$1" : "$2"`))
inp is the variable that holds the original data format.
However, now I get a new format:
id=1 name=peter age=12
and I also want to convert to JSON string using similar method that I used above, i.e., use regex to do a one pass formatting.
{"id"="1", "name"="peter", "age"="12"}
How can I achieve that?
UPDATE: One additional requirement. if the input format is
id=1, name=peter, age="12"
I need to get rid of the "" to be or escape \" so I can process in the next step. The double quote can appear at the beginning and the end of any value field.

Answer 1

There are two parts to the question: The easy part is serialising to JSON, Go has standard library methods for doing that. I would use that library rather than trying to encode the JSON myself.
The slightly trickier part of your question is parsing the input into a struct or map that can be easily serialised out, and making it flexible enough to accept different input formats.
I would do it with a general interface for converting text to a struct or map, and then implementing the interface for parsing each new input type.
Sample code: (You can run it here)
package main
import (
"encoding/json"
"errors"
"fmt"
"strings"
)
// parseFn describes the function for converting input into a map.
// This could be a struct or something else if the format is well known.
// In real code this would return map[string]interface{}, but for this
// demo I'm just using string
type parseFn func(string) (map[string]string, error)
// parseFormat1 is for fields separated by commas
func parseFormat1(in string) (map[string]string, error) {
data := map[string]string{}
fields := strings.Split(in, ",")
for _, field := range fields {
pair := strings.Split(field, "=")
if len(pair) != 2 {
return nil, errors.New("invalid input")
}
data[strings.Trim(pair[0], ` "`)] = strings.Trim(pair[1], ` "`)
}
return data, nil
}
// parseFormat2 is for lines with no commas
func parseFormat2(in string) (map[string]string, error) {
data := map[string]string{}
fields := strings.Split(in, " ")
for _, field := range fields {
pair := strings.Split(field, "=")
if len(pair) != 2 {
return nil, errors.New("invalid input")
}
data[strings.Trim(pair[0], ` "`)] = strings.Trim(pair[1], ` "`)
}
return data, nil
}
// nullFormat is what we fall back on when we just don't know
func nullFormat(in string) (map[string]string, error) { return nil, errors.New("invalid format") }
// classify just tries to guess the parser to use for the input
func classify(in string) parseFn {
switch {
case strings.Count(in, ", ") > 1:
return parseFormat1
case strings.Count(in, " ") > 1:
return parseFormat2
default:
return nullFormat
}
}
func main() {
testCases := []string{
`id=1, name=peter, age=12`,
`id=1, name=peter, age="12"`,
`id=1 name=peter age=12`,
`id=1;name=peter;age="12"`,
}
for ix, tc := range testCases {
pfn := classify(tc)
d, err := pfn(tc)
if err != nil {
fmt.Printf("\nerror parsing on line %d: %v\n", ix, err)
continue
}
b, err := json.Marshal(d)
if err != nil {
fmt.Printf("\nerror marshaling on line %d: %v\n", ix, err)
continue
}
fmt.Printf("\nSuccess on line %d:\n INPUT: %s\nOUTPUT: %s\n", ix, tc, string(b))
}
}