I'm working on a simple REST API and I'm having troubles with the PATCH method. I don't know how can i tell the method and the query which fields i want to update(for example which fields are passed as JSON) in the database. Here is what i have so far.
func PatchServer(c echo.Context) error {
patchedServer := new(structs.Server)
requestID := c.Param("id")
if err := c.Bind(patchedServer); err != nil {
return err
}
sql := "UPDATE servers SET server_name = CASE WHEN ? IS NOT NULL THEN ? END WHERE id = ?"
stmt, err := db.Get().Prepare(sql)
if err != nil {
panic(err)
}
_, err2 := stmt.Exec(patchedServer.Name, patchedServer.Name, requestID)
if err2 != nil {
panic(err2)
}
fmt.Println(patchedServer.ID, patchedServer.Name, patchedServer.Components)
fmt.Println("Requested id: ", requestID)
return c.JSON(http.StatusOK, "Patched!")
}
Related
I am dealing with a bit over 15 billion rows of data in various text files. I am trying to insert them into MariaDB using golang. Golang is a fast language and is often used for big data but I cannot get more than 10k-15k inserts a second, at this rate its gonna take over 15 days, I need this data imported sooner than that. I have tried various batch sizes but they all give about the same results.
function I'm using to handle file data:
func handlePath(path string) {
file, err := os.Open(path)
if err != nil {
fmt.Printf("error opening %v: %v", path, err)
return
}
defer file.Close()
scanner := bufio.NewScanner(file)
var temp_lines []string
for scanner.Scan() {
if len(temp_lines) == line_batch {
insertRows(temp_lines)
temp_lines = []string{}
}
temp_lines = append(temp_lines, scanner.Text())
}
insertRows(temp_lines)
fmt.Printf("\nFormatted %v\n", path)
if err := scanner.Err(); err != nil {
fmt.Printf("\nScanner error %v\n", err)
return
}
}
function I'm using for inserting:
func insertRows(rows []string) {
var Args []string
for _, row := range rows {
line_split := strings.Split(row, "|")
if len(line_split) != 6 {return}
database_id := line_split[0]
email := line_split[1]
password := line_split[2]
username := line_split[3]
ip := line_split[4]
phone := line_split[5]
arg := fmt.Sprintf("('%v','%v','%v','%v','%v','%v')",database_id,email,password,username,ip,phone)
Args = append(Args, arg)
}
sqlQuery := fmt.Sprintf("INSERT INTO new_table (database_id, email, password, username, ip, phone_number) VALUES %s", strings.Join(Args, ","))
_, err := db.Exec(sqlQuery)
if err != nil {
//fmt.Printf("%v\n", err)
return
}
total+=line_batch
writes++
}
Server specs:
server
I am currently in the process of creating a little Go App. Right now I am working on the DB part. The Library I use is this one: https://github.com/jackc/pgx
The problem I have is that every time I try to execute the database read, it tells me that my 'conn is busy'. I read about using a pgxpool instead of a single connection, but it still does not work. What am I doing wrong?
func (postgre *PostgreClient) read(query string) (pgx.Row, error) {
client, err := postgre.client.Acquire(context.TODO())
transaction, err := client.BeginTx(context.TODO(), pgx.TxOptions{})
if err != nil {
return nil, err
}
defer transaction.Rollback(context.TODO())
rows := transaction.QueryRow(context.TODO(), query)
if err != nil {
return nil, err
}
err = transaction.Commit(context.TODO())
return rows, err
}
Thanks in advance.
You have to scan the row before you commit the transaction.
If you want the handling of the transaction to remain within the function you can pass an interface that does the scanning also inside the function.
For example:
// implemented by *sql.Row & *sql.Rows
type Row interface {
Scan(dst ...interface{}) error
}
// implemented by your "models"
type RowScanner interface {
ScanRow(r Row) error
}
type User struct {
Id int
Email string
}
func (u *User) ScanRow(r Row) error {
return r.Scan(
&u.Id,
&u.Email,
)
}
func (postgre *PostgreClient) read(query string, rs RowScanner) (err error) {
conn, err := postgre.client.Acquire(context.TODO())
if err != nil {
return err
}
defer conn.Release()
tx, err := conn.BeginTx(context.TODO(), pgx.TxOptions{})
if err != nil {
return err
}
defer func() {
if err != nil {
tx.Rollback(context.TODO())
} else {
tx.Commit(context.TODO())
}
}()
row := tx.QueryRow(context.TODO(), query)
if err != nil {
return nil, err
}
return rs.ScanRow(row)
}
u := new(User)
if err := pg.read("select id, email from users limit 1", u); err != nil {
panic(err)
}
For scanning a list of models:
type UserList []*User
func (ul *UserList) ScanRow(r Row) error {
u := new(User)
if err := u.ScanRow(r); err != nil {
return err
}
*ul = append(*ul, u)
return nil
}
func (postgre *PostgreClient) list(query string, rs RowScanner) (err error) {
conn, err := postgre.client.Acquire(context.TODO())
if err != nil {
return err
}
defer conn.Release()
tx, err := conn.BeginTx(context.TODO(), pgx.TxOptions{})
if err != nil {
return err
}
defer func() {
if err != nil {
tx.Rollback(context.TODO())
} else {
tx.Commit(context.TODO())
}
}()
rows, err := tx.Query(context.TODO(), query)
if err != nil {
return err
}
defer rows.Close()
for rows.Next() {
if err := rs.ScanRow(rows); err != nil {
return err
}
}
return rows.Err()
}
ul := new(UserList)
if err := pg.list("select id, email from users", ul); err != nil {
panic(err)
}
I have a main.go file with a sql query saved as a string.
defer db.Close()
id := 1
// format this query
row := db.QueryRow("SELECT f_name, l_name from users WHERE id = ?", id)
var fname, lname string
err = row.Scan(&fname, &lname)
if err != nil {
log.Fatal(err)
}
fmt.Printf("%v %v\n", fname, lname)
Is there a way to format that line?
I have also had the same problem. For me, the best solution is to move the SQL query to an embed file and format it there. This also has the advantage of making more complex or larger SQL queries more readable.
For *.sql files can than be a plugin used. For example Language PL/SQL.
Here is an example:
Excerpt of a repository (sqlite3,postgres,...)
package repository
import (
"context"
"database/sql"
_ "embed"
)
//go:embed dml/selectUsers.sql
var selectUsers string
type Repository struct{
sqlDB *sql.DB
}
func (r *Repository) GetUsers()([]*User,error){
tx, err := s.sqlDb.BeginTx(ctx, &sql.TxOptions{ReadOnly: false})
if err != nil {
return nil, fmt.Errorf("failed to begin new transaction: %w", err)
}
defer tx.Close()
selectedUsers, err := r.selectUsers(tx, selectUsers)
if err != nil {
return nil, fmt.Errorf("failed to select users: %w", err)
}
err = tx.Commit()
if err != nil {
return nil, fmt.Errorf("failed to commit transaction: %w", err)
}
return selectedUsers, nil
}
func (r *Repository) selectUsers(tx *sql.Tx, query string, args ...interface{}) ([]*User,error) {
stmt, err := tx.Prepare(insertCompany)
if err != nil {
return nil, fmt.Errorf("failed to prepare statement: %v", err)
}
defer stmt.Close()
rows, err := stmt.Query(args...)
if err != nil {
return nil, fmt.Errorf("failed to query statement: %v", err)
}
selectedUsers := make([]*User, 0)
for rows.Next() {
selectedUser := new(User)
err = rows.Scan(
&selectedUser.ID,
&selectedUser.Surename,
&selectedUser.Familyname,
)
if err != nil {
return nil, fmt.Errorf("failed to scan row: %v", err)
}
selectedUsers = append(selectedUsers, selectedUser)
}
return selectedUsers, nil
}
dml/selectUsers.sql
SELECT
id,
surename,
familyname
FROM
users;
For the context, I'm new to go and I'm creating a program that can copy tables from Oracle to MySQL.
I use database/sql go package, so I assume it can be used for migrating any kind of database.
To simplify my question I'm coping on the same MySQL database table name world.city to world.city_copy2.
with my following code, I ended up with the same last values in all the rows in the table :-(
do I somehow need to read through all the values inside the loop? what is the efficient way to do that?
package main
import (
"database/sql"
"fmt"
"strings"
_ "github.com/go-sql-driver/mysql"
)
const (
user = "user"
pass = "testPass"
server = "localhost"
)
func main() {
fmt.Print("test")
conStr := fmt.Sprintf("%s:%s#tcp(%s)/world", user, pass, server)
db, err := sql.Open("mysql", conStr)
if err != nil {
panic(err.Error())
}
defer db.Close()
err = db.Ping()
if err != nil {
panic(err.Error())
}
rows, err := db.Query("SELECT * FROM city")
if err != nil {
panic(err.Error()) // proper error handling instead of panic in your app
}
columns, err := rows.Columns()
if err != nil {
panic(err.Error()) // proper error handling instead of panic in your app
}
// Make a slice for the values
values := make([]sql.RawBytes, len(columns))
// rows.Scan wants '[]interface{}' as an argument, so we must copy the
// references into such a slice
scanArgs := make([]interface{}, len(values))
for i := range values {
scanArgs[i] = &values[i]
}
// that string will be generated according to len of columns
placeHolders := "( ?, ?, ?, ?, ? )"
// slice will contain all the values at the end
bulkValues := []interface{}{}
valueStrings := make([]string, 0)
for rows.Next() {
// get RawBytes from data
err = rows.Scan(scanArgs...)
if err != nil {
panic(err.Error()) // proper error handling instead of panic in your app
}
valueStrings = append(valueStrings, placeHolders)
bulkValues = append(bulkValues, scanArgs...)
//
}
stmStr := fmt.Sprintf("INSERT INTO city_copy2 VALUES %s", strings.Join(valueStrings, ","))
_, err = db.Exec(stmStr, bulkValues...)
if err != nil {
panic(err.Error())
}
}
I have checked out the docs of the library, and it seems that the problem here is that bulkValues keeps the address of the pointer so when scanArgs changes, bulkValues also changes to latest value of that scanArgs.
You need to use the values variable to get the values like below:
func main() {
fmt.Print("test")
conStr := fmt.Sprintf("%s:%s#tcp(%s)/soverflow", user, pass, server)
db, err := sql.Open("mysql", conStr)
if err != nil {
panic(err.Error())
}
defer db.Close()
err = db.Ping()
if err != nil {
panic(err.Error())
}
rows, err := db.Query("SELECT * FROM city")
if err != nil {
panic(err.Error()) // proper error handling instead of panic in your app
}
columns, err := rows.Columns()
if err != nil {
panic(err.Error()) // proper error handling instead of panic in your app
}
// Make a slice for the values
values := make([]sql.RawBytes, len(columns))
// rows.Scan wants '[]interface{}' as an argument, so we must copy the
// references into such a slice
scanArgs := make([]interface{}, len(values))
for i := range values {
scanArgs[i] = &values[i]
}
// that string will be generated according to len of columns
placeHolders := "( ?, ?, ?, ?, ? )"
// slice will contain all the values at the end
bulkValues := []interface{}{}
valueStrings := make([]string, 0)
// make an interface to keep the record's value
record := make([]interface{}, len(columns))
for rows.Next() {
// get RawBytes from data
err = rows.Scan(scanArgs...)
if err != nil {
panic(err.Error()) // proper error handling instead of panic in your app
}
valueStrings = append(valueStrings, placeHolders)
for i, col := range values {
// you need to be carefull with the datatypes here
// check out the docs for details on here
record[i] = string(value)
}
bulkValues = append(bulkValues, record...)
}
stmStr := fmt.Sprintf("INSERT INTO city_copy2 VALUES %s", strings.Join(valueStrings, ","))
_, err = db.Exec(stmStr, bulkValues...)
if err != nil {
panic(err.Error())
}
}
You can also find the example of the documentation here.
Note: There might be more efficient ways to copy database from psql to mysql but this answer only gives a quick solution for this particular issue that you are having.
I'm trying to put a (key,value) in aerospike
that it's value is: ("mykey",3).
is this the correct technique?
because i cannot fetch it...
key, err := as.NewKey("namespace", "set","mykey")
if err != nil {
log.Fatal(err)
}
exists, err := client.Exists(Policy, key)
if exists {
// Read a record
record, err := client.Get(Policy, key)
if err != nil {
log.Fatal(err)
}
var newval = 3
}
bin1 := as.NewBin("bin1", newval )
// Write a record
err = client.PutBins(WritePolicy, key, bin1)