如何在golang中切掉uuid？

Question

In order to make semi-random slugs, I'd like to use first 8 characters of uuid. So I have

import (
    fmt
    "github.com/satori/go.uuid"
)

    u1 := uuid.NewV4()
    fmt.Println("u1 :", u1)

    runes := []rune(u1)
    slug := string(runes[0:7]) 

But in compile time I get this error:

cannot convert u1 (type uuid.UUID) to type []rune

How can I fix it?

Answer 1

In that package (I just looked at the source code) a UUID is an alias for [16]byte, so you cannot concert it to a rune array, not that you want to.

Try this:

s := hex.EncodeToString(u1.Bytes()[:4])

This will give you 8 hex digits. However, this is still a roundabout way of doing things. A v4 UUID is random except for certain bits, so if you are not using the whole UUID it is more straightforward to just generate 4 random bytes. Use the Read() function in math/rand (which must be seeded) or crypto/rand (which is what the UUID library uses).

b := make([]byte, 4)
rand.Read(b) // Doesn’t actually fail
s := hex.EncodeToString(b)