Add identifier function for use in templates.

strmangle/strmangle.go

@@ -6,11 +6,42 @@ package strmangle
 
 import (
 	"fmt"
+	"math"
 	"strings"
 
 	"github.com/jinzhu/inflection"
 )
 
+var (
+	idAlphabet = []byte("abcdefghijklmnopqrstuvwxyz")
+)
+
+// Identifier creates an identifier useful for a query
+// This is essentially a base conversion from Base 10 integers to Base 26
+// integers that are represented by an alphabet from a-z
+// See tests for example outputs.
+func Identifier(in int) string {
+	ln := len(idAlphabet)
+	var n int
+	if in == 0 {
+		n = 1
+	} else {
+		n = 1 + int(math.Log(float64(in))/math.Log(float64(ln)))
+	}
+
+	cols := make([]byte, n)
+
+	for i := 0; i < n; i++ {
+		divisor := int(math.Pow(float64(ln), float64(n-i-1)))
+		rem := in / divisor
+		cols[i] = idAlphabet[rem]
+
+		in -= rem * divisor
+	}
+
+	return string(cols)
+}
+
 // Plural converts singular words to plural words (eg: person to people)
 func Plural(name string) string {
 	splits := strings.Split(name, "_")

strmangle/strmangle_test.go

@@ -5,6 +5,28 @@ import (
 	"testing"
 )
 
+func TestIDGen(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		In  int
+		Out string
+	}{
+		{In: 0, Out: "a"},
+		{In: 25, Out: "z"},
+		{In: 26, Out: "ba"},
+		{In: 52, Out: "ca"},
+		{In: 675, Out: "zz"},
+		{In: 676, Out: "baa"},
+	}
+
+	for _, test := range tests {
+		if got := Identifier(test.In); got != test.Out {
+			t.Errorf("[%d] want: %q, got: %q", test.In, test.Out, got)
+		}
+	}
+}
+
 func TestDriverUsesLastInsertID(t *testing.T) {
 	t.Parallel()