The function does not accept or return a structure?

Question

go

Hello. Briefly: the MainPage function processes the main page and also unloads the table from the database into a slice of structures.
Next From this slice of structures, a random object is taken, assigned to the show variable, which is passed to the page to display data from the database.

type WordsStruct struct {
  Id    int
  Fword string
  Sword string
  Freq  int
}

func MainPage(w http.ResponseWriter, r *http.Request) {

  m, _ := template.ParseFiles("html/main.html", "html/header.html", "html/footer.html")

  res, err := database.Query(fmt.Sprintf("SELECT * FROM `words`"))
  if err != nil {
    panic(err)
  }
  defer res.Close()

  showarray := []WordsStruct{}

  for res.Next() {
    var sw WordsStruct
    err := res.Scan(&sw.Id, &sw.Fword, &sw.Sword, &sw.Freq)
    if err != nil {
      fmt.Println(err)
      continue
    }

    showarray = append(showarray, sw)
  }

  rand.Seed(time.Now().Unix())
  show := showarray[rand.Intn(len(showarray))]

  //w.Header().Set("Content-Type", "text/html")
  m.ExecuteTemplate(w, "main", show)
}

Next, the user presses the "Next" button on the page and sees the next random structure from the slice.
The whole crutch is tied to the fact that when you click on "Next", the page is updated and the code is executed again.
Those. for optimization, it is necessary to bring the extraction of a random object from a slice of structures into a separate function.

So instead of code with randomization:

rand.Seed(time.Now().Unix())
show := showarray[rand.Intn(len(showarray))]

you need to call a function with this operation, in the argument of which we put a slice of structures, and return a random structure object that is sent to the page:

show := Next(showarray)

// ***

func Next(st []struct{}) struct{} {
  rand.Seed(time.Now().Unix())
  shw := st[rand.Intn(len(st))]
  return shw
}

But the most common mistake: either you cannot pass a structure as an argument, or you cannot return it.
In 7 hours of searching for a solution, I tried many syntax options and tricks.
I can give a link to the entire code in the git, if necessary.
Thanks

Answer 1

To be honest, I didn’t quite understand why in the code you show that you are passing st []struct{} and returning struct{}, you need to specify a specific data type. Here is the working code

package main

import (
  "fmt"
  "math/rand"
  "time"
)

type WordsStruct struct {
  Id    int
  Fword string
  Sword string
  Freq  int
}

func Next(st []WordsStruct) WordsStruct {
  rand.Seed(time.Now().Unix())
  shw := st[rand.Intn(len(st))]
  return shw
}

func main(){
  st := []WordsStruct{
    {Id: 1, Fword: "test", Sword:"est" , Freq:5 },
    {Id: 2, Fword: "rest", Sword:"ww" , Freq:75 },
  }
  fmt.Println(Next(st))
}