We often work with configuration strings like pq database connection:
user=mylogin password=mypass database=mydb host=127.0.0.1 port=5432 sslmode=true
The simplest way to parse them in Golang is regular expressions:
package main
import (
"fmt"
"regexp"
)
var rex = regexp.MustCompile("(\\w+)=(\\w+)")
func main() {
conn := `user=mylogin password=mypass database=mydb
host=127.0.0.1 port=5432 sslmode=true`
data := rex.FindAllStringSubmatch(conn, -1)
res := make(map[string]string)
for _, kv := range data {
k := kv[1]
v := kv[2]
res[k] = v
}
fmt.Println(res)
}But if the value can contain a space character, then you need to add escaping support in a regular expression. And so on, each additional action makes processing harder. But there is an easier way (wmentor/dsn).
Install package:
go get github.com/wmentor/dsn
Usage:
package main
import (
"fmt"
"github.com/wmentor/dsn"
)
func main() {
str := `user=mylogin passwd=mypass database=mydb
port=5432 sslmode=true`
ds, err := dsn.New(str)
if err != nil {
panic("invalid string")
}
// print user=mylogin
fmt.Printf( "user=%s\n", ds.GetString("user","unknown") )
// print passwd=mypass
fmt.Printf( "passwd=%s\n", ds.GetString("passwd","nopass") )
// host is not exists, print host=127.0.0.1
fmt.Printf( "host=%s\n", ds.GetString("host","127.0.0.1") )
// get int value and print port=5432
fmt.Printf( "port=%d\n", ds.GetInt("port", 4321) )
// print sslmode=true
fmt.Printf( "sslmode=%t\n", ds.GetBool("sslmode", false) )
// print keepalive=false
fmt.Printf( "keepalive=%t\n", ds.GetBool("keepalive", false) )
}dns.New returns object dsn.DSN or an error. All get methods (GetString,GetBool,GetInt,GetInt64,GetFloat) take 2 arguments - key name and default value. The default value is used when the key is missing or contains a invalid value.
Moreover, dsn support escape some characters in key name and value (\s,\t,\r,\n,=,\,",'). See example below:
package main
import (
"fmt"
"github.com/wmentor/dsn"
)
func main() {
str := `message=Hello,\sWorld! calc=1+1\=2`
ds, err := dsn.New(str)
if err != nil {
panic("invalid string")
}
// print message=Hello, World!
fmt.Printf( "message=%s\n", ds.GetString("message","") )
// print calc=1+2=2
fmt.Printf( "calc=%s\n", ds.GetString("calc","") )
}Object dsn.DSN support set methods (SetString,SetBool,SetInt,SetInt64,SetFloat). They take 2 arguments - key name and value:
ds.SetString("host", "192.168.1.1")Stringer interface implemention makes simple convert dsn.DSN to string:
str := ds.String()
// or
fmt.Println(ds)