Sort 2D array of structs Golang - go

Question

I want to create a consistent ordering for a 2D slice of structs, I am creating the 2D slice from a map so the order is always different.
My structs look like
// Hit contains the data for a hit.
type Hit struct {
Key string `json:"key"`
Data []Field `json:"data"`
}
// Hits stores a list of hits.
type Hits [][]Hit
I want to provide a consistent order for the contents of my Hits type.
I have tried:
func (c Hits) Len() int { return len(c) }
func (c Hits) Swap(i, j int) { c[i], c[j] = c[j], c[i] }
func (c Hits) Less(i, j int) bool { return strings.Compare(c[i][0].Key, c[j][0].Key) == -1 }
But the results still seem to come back in random order.
I was thinking of possibly hashing each item in the slice but thought there might be an easier option

Answer 1

The order of iteration over a map, because it's a hash table is rather indeterminate (it's not, really — insert items with the same keys in the same exact sequence into 2 maps and the order of iteration for each will be identical).
Assuming that your map is a map[string]Hit, to iterate it over in a determinate order, I would enumerate the set of keys in the map, sort that, and use that sorted set to enumerate the map.
Something like this:
package main
import (
"fmt"
"sort"
)
type Hit struct {
Key string `json:"key"`
Data []Field `json:"data"`
}
type Field struct {
Value string `json:"value"`
}
func main() {
var mapOfHits = getSomeHits()
var sortedHits = sortHits(mapOfHits)
for _, h := range sortedHits {
fmt.Println(h.Key)
}
}
func getSomeHits() map[string]Hit {
return make(map[string]Hit, 0)
}
func sortHits(m map[string]Hit) []Hit {
keys := make([]string, 0, len(m))
sorted := make([]Hit, 0, len(m))
for k := range m {
keys = append(keys, k)
}
sort.Strings(keys)
for _, k := range keys {
sorted = append(sorted, m[k])
}
return sorted
}