filter enhancements

tools/list/list.go

@@ -10,6 +10,20 @@ import (
 
 var cachedPatterns = map[string]*regexp.Regexp{}
 
+// SubtractSlice returns a new slice with only the "base" elements
+// that don't exist in "subtract".
+func SubtractSlice[T comparable](base []T, subtract []T) []T {
+	var result = make([]T, 0, len(base))
+
+	for _, b := range base {
+		if !ExistInSlice(b, subtract) {
+			result = append(result, b)
+		}
+	}
+
+	return result
+}
+
 // ExistInSlice checks whether a comparable element exists in a slice of the same type.
 func ExistInSlice[T comparable](item T, list []T) bool {
 	if len(list) == 0 {

tools/list/list_test.go

@@ -1,12 +1,111 @@
 package list_test
 
 import (
+	"encoding/json"
 	"testing"
 
 	"github.com/pocketbase/pocketbase/tools/list"
 	"github.com/pocketbase/pocketbase/tools/types"
 )
 
+func TestSubtractSliceString(t *testing.T) {
+	scenarios := []struct {
+		base     []string
+		subtract []string
+		expected string
+	}{
+		{
+			[]string{},
+			[]string{},
+			`[]`,
+		},
+		{
+			[]string{},
+			[]string{"1", "2", "3", "4"},
+			`[]`,
+		},
+		{
+			[]string{"1", "2", "3", "4"},
+			[]string{},
+			`["1","2","3","4"]`,
+		},
+		{
+			[]string{"1", "2", "3", "4"},
+			[]string{"1", "2", "3", "4"},
+			`[]`,
+		},
+		{
+			[]string{"1", "2", "3", "4", "7"},
+			[]string{"2", "4", "5", "6"},
+			`["1","3","7"]`,
+		},
+	}
+
+	for i, s := range scenarios {
+		result := list.SubtractSlice(s.base, s.subtract)
+
+		raw, err := json.Marshal(result)
+		if err != nil {
+			t.Fatalf("(%d) Failed to serialize: %v", i, err)
+		}
+
+		strResult := string(raw)
+
+		if strResult != s.expected {
+			t.Fatalf("(%d) Expected %v, got %v", i, s.expected, strResult)
+		}
+	}
+}
+
+func TestSubtractSliceInt(t *testing.T) {
+	scenarios := []struct {
+		base     []int
+		subtract []int
+		expected string
+	}{
+		{
+			[]int{},
+			[]int{},
+			`[]`,
+		},
+		{
+			[]int{},
+			[]int{1, 2, 3, 4},
+			`[]`,
+		},
+		{
+			[]int{1, 2, 3, 4},
+			[]int{},
+			`[1,2,3,4]`,
+		},
+		{
+			[]int{1, 2, 3, 4},
+			[]int{1, 2, 3, 4},
+			`[]`,
+		},
+		{
+			[]int{1, 2, 3, 4, 7},
+			[]int{2, 4, 5, 6},
+			`[1,3,7]`,
+		},
+	}
+
+	for i, s := range scenarios {
+		result := list.SubtractSlice(s.base, s.subtract)
+
+		raw, err := json.Marshal(result)
+		if err != nil {
+			t.Fatalf("(%d) Failed to serialize: %v", i, err)
+		}
+
+		strResult := string(raw)
+
+		if strResult != s.expected {
+			t.Fatalf("(%d) Expected %v, got %v", i, s.expected, strResult)
+		}
+	}
+}
+
 func TestExistInSliceString(t *testing.T) {
 	scenarios := []struct {
 		item     string