I'm trying to create a very simple Bolt database called "ledger.db" that includes one Bucket, called "Users", which contains Usernames as a Key and Balances as the value that allows users to transfer their balance to one another. I am using Bolter to view the database in the command line
There are two problems, both contained in this transfer function issue resides in the transfer function.
The First: Inside the transfer function is an if/else. If the condition is true, it executes as it should. If it's false, nothing happens. There's no syntax errors and the program runs as though nothing is wrong, it just doesn't execute the else statement.
The Second: Even if the condition is true, when it executes, it doesn't update BOTH the respective balance values in the database. It updates the balance of the receiver, but it doesn't do the same for the sender. The mathematical operations are completed and the values are marshaled into a JSON-compatible format.
The problem is that the sender balance is not updated in the database.
Everything from the second "Success!" fmt.Println() function onward is not processed
I've tried changing the "db.Update()" to "db.Batch()". I've tried changing the order of the Put() functions. I've tried messing with goroutines and defer, but I have no clue how to use those, as I am rather new to golang.
func (from *User) transfer(to User, amount int) error{
var fbalance int = 0
var tbalance int = 0
db, err := bolt.Open("ledger.db", 0600, nil)
if err != nil {
log.Fatal(err)
}
defer db.Close()
return db.Update(func(tx *bolt.Tx) error {
uBuck := tx.Bucket([]byte("Users"))
json.Unmarshal(uBuck.Get([]byte(from.username)), &fbalance)
json.Unmarshal(uBuck.Get([]byte(to.username)), &tbalance)
if (amount <= fbalance) {
fbalance = fbalance - amount
encoded, err := json.Marshal(fbalance)
if err != nil {
return err
}
tbalance = tbalance + amount
encoded2, err := json.Marshal(tbalance)
if err != nil {
return err
}
fmt.Println("Success!")
c := uBuck
err = c.Put([]byte(to.username), encoded2)
return err
fmt.Println("Success!")
err = c.Put([]byte(from.username), encoded)
return err
fmt.Println("Success!")
} else {
return fmt.Errorf("Not enough in balance!", amount)
}
return nil
})
return nil
}
func main() {
/*
db, err := bolt.Open("ledger.db", 0600, nil)
if err != nil {
log.Fatal(err)
}
defer db.Close()
*/
var b User = User{"Big", "jig", 50000, 0}
var t User = User{"Trig", "pig", 40000, 0}
// These two functions add each User to the database, they aren't
// the problem
b.createUser()
t.createUser()
/*
db.View(func(tx *bolt.Tx) error {
c := tx.Bucket([]byte("Users"))
get := c.Get([]byte(b.username))
fmt.Printf("The return value %v",get)
return nil
})
*/
t.transfer(b, 40000)
}
I expect the database to show Big:90000 Trig:0 from the beginning values of Big:50000 Trig:40000
Instead, the program outputs Big:90000 Trig:40000
