I need to use strings.Join(invoicesBatch, ",") to join a string array. But the array I got from the map using reflect.ValueOf(invoiceList).MapKeys() is reflect.Value array. Is there a easy way to convert them into a string array.
The map was initialized with string key.
You will need to use loop but you won't need to create a new slice every time as we already know the length. Example:
func main() {
a := map[string]int{
"A": 1, "B": 2,
}
keys := reflect.ValueOf(a).MapKeys()
strkeys := make([]string, len(keys))
for i := 0; i < len(keys); i++ {
strkeys[i] = keys[i].String()
}
fmt.Print(strings.Join(strkeys, ","))
}
instead of using reflection you can use a for loop and range to get a slice of keys like this
package main
import (
"fmt"
"strings"
)
func main() {
data := map[string]int{
"A": 1,
"B": 2,
}
keys := make([]string, 0, len(data))
for key := range data {
keys = append(keys, key)
}
fmt.Print(strings.Join(keys, ","))
}
Interesting enough that I've got a bit strange result while tried to get keys list from the dictionary using @zola's approach. The snippet I was using:
package main
import "strings"
func main() {
dict := map[string]int {"A": 1, "B": 2}
keys := make([]string, len(dict))
for key, _ := range dict {
keys = append(keys, key)
}
println(strings.Join(keys, ", "))
println(len(keys))
}
And, here is the output:
, , A, B
4
Seems like the capacity of the array storing keys was extended or something when it became full? Finally, I was using this approach:
package main
import "strings"
func main() {
dict := map[string]int {"A": 1, "B": 2}
keys := make([]string, len(dict))
i := 0
for key, _ := range dict {
keys[i] = key // explicit array element assignment instead of append function
i += 1
}
println(strings.Join(keys, ", "))
println(len(keys))
}
Not sure what is the reason. Probably it is a known bug, or I don't fully understand how Go works. For future reference, I'm using go version go1.10.3 darwin/amd64 and GoLand 2018.2.3.