/
func.go
103 lines (89 loc) · 2.22 KB
/
func.go
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package main
import (
"bytes"
"database/sql"
"encoding/json"
"io/ioutil"
"log"
"os"
"strconv"
"github.com/pkg/errors"
_ "github.com/lib/pq"
)
var (
// command to execute, 'SELECT' or 'INSERT'
command = os.Getenv("HEADER_COMMAND")
// postgres host:port, e.g. 'postgres:5432'
server = os.Getenv("HEADER_SERVER")
// postgres table name
table = os.Getenv("HEADER_TABLE")
)
func main() {
req, err := ioutil.ReadAll(os.Stdin)
if err != nil {
log.Fatal(errors.Wrap(err, "failed to read stdin"))
}
db, err := sql.Open("postgres", "postgres://postgres@"+server+"?sslmode=disable")
if err != nil {
log.Println("Failed to connect to postgres server")
log.Fatal(err)
return
}
switch command {
case "SELECT":
if resp, err := selectCommand(req, db); err != nil {
log.Fatal(errors.Wrap(err, "select command failed"))
} else {
log.Println(resp)
}
case "INSERT":
if err := insertCommand(req, db); err != nil {
log.Fatal(errors.Wrap(err, "insert command failed"))
}
default:
log.Fatalf("invalid command: %q", command)
}
}
func selectCommand(req []byte, db *sql.DB) (string, error) {
// Parse request JSON
var params map[string]interface{}
if err := json.Unmarshal(req, ¶ms); err != nil {
return "", errors.Wrap(err, "failed to parse json")
}
// Build query and gather arguments
var query bytes.Buffer
var args []interface{}
query.WriteString("SELECT json_agg(t) FROM (SELECT * FROM ")
query.WriteString(table)
query.WriteString(" WHERE")
first := true
arg := 1
for k, v := range params {
args = append(args, v)
if !first {
query.WriteString(" AND")
}
query.WriteString(" ")
query.WriteString(k)
query.WriteString("=$")
query.WriteString(strconv.Itoa(arg))
arg += 1
first = false
}
query.WriteString(") AS t")
// Execute query
r := db.QueryRow(query.String(), args...)
var resp string
if err := r.Scan(&resp); err != nil {
return "", errors.Wrap(err, "failed to execute select query")
}
return resp, nil
}
func insertCommand(req []byte, db *sql.DB) error {
q := "INSERT INTO " + table + " SELECT * FROM json_populate_record(null::" + table + ", $1)"
_, err := db.Exec(q, req)
if err != nil {
return errors.Wrap(err, "Failed to execute insert query")
}
return nil
}