feat: Add KeysInValidator for validating fields containing specific keys

lang/default.go

@@ -189,6 +189,8 @@ var enUS = &Language{
 			"unique.element":                     "The :field element value has already been taken.",
 			"exists":                             "The :field does not exist.",
 			"exists.element":                     "The :field element value does not exist.",
+			"keysin":                             "The :field keys must be one of the following: :values.",
+			"keysin.element":                     "The :field elements keys must be one of the following: :values.",
 			"doesnt_end_with":                    "The :field must not end with any of the following values: :values.",
 			"doesnt_end_with.element":            "The :field elements must not end with any of the following values: :values.",
 		},

validation/keysin.go

@@ -0,0 +1,46 @@
+package validation
+
+import "strings"
+
+// KeysInValidator the field under validation must be an object and all its keys must
+// be equal to one of the given values.
+type KeysInValidator struct {
+	BaseValidator
+	Keys []string
+}
+
+// Validate checks the field under validation satisfies this validator's criteria.
+func (v *KeysInValidator) Validate(ctx *Context) bool {
+	obj, ok := ctx.Value.(map[string]any)
+	if !ok {
+		return false
+	}
+
+	allowedKeys := make(map[string]struct{})
+	for _, key := range v.Keys {
+		allowedKeys[key] = struct{}{}
+	}
+
+	for key := range obj {
+		if _, ok := allowedKeys[key]; !ok {
+			return false
+		}
+	}
+	return true
+}
+
+// Name returns the string name of the validator.
+func (v *KeysInValidator) Name() string { return "keys_in" }
+
+// MessagePlaceholders returns the ":values" placeholder.
+func (v *KeysInValidator) MessagePlaceholders(_ *Context) []string {
+	return []string{
+		":values", strings.Join(v.Keys, ", "),
+	}
+}
+
+// KeysIn the field under validation must be an object and all its keys must
+// be equal to one of the given values.
+func KeysIn(keys ...string) *KeysInValidator {
+	return &KeysInValidator{Keys: keys}
+}

validation/keysin_test.go

@@ -0,0 +1,47 @@
+package validation
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestKeysInValidator(t *testing.T) {
+	t.Run("Constructor", func(t *testing.T) {
+		v := KeysIn("a", "b", "c")
+		assert.NotNil(t, v)
+		assert.Equal(t, "keys_in", v.Name())
+		assert.False(t, v.IsType())
+		assert.False(t, v.IsTypeDependent())
+		assert.Equal(t, []string{":values", "a, b, c"}, v.MessagePlaceholders(&Context{}))
+	})
+
+	cases := []struct {
+		input       any
+		allowedKeys []string
+		want        bool
+	}{
+		{allowedKeys: []string{"a", "b", "c"}, input: map[string]any{"a": 1, "b": 2, "c": 3}, want: true},
+		{allowedKeys: []string{"a", "b", "c"}, input: map[string]any{"a": 1, "b": 2, "c": 3, "d": 4}, want: false},
+		{allowedKeys: []string{"a", "b", "c"}, input: map[string]any{"a": 1, "b": 2}, want: true},
+		{allowedKeys: []string{"a", "b", "c"}, input: map[string]any{}, want: true},
+		{allowedKeys: []string{"a", "b", "c"}, input: "", want: false},
+		{allowedKeys: []string{"a", "b", "c"}, input: 'a', want: false},
+		{allowedKeys: []string{"a", "b", "c"}, input: 2, want: false},
+		{allowedKeys: []string{"a", "b", "c"}, input: 2.5, want: false},
+		{allowedKeys: []string{"a", "b", "c"}, input: true, want: false},
+		{allowedKeys: []string{"a", "b", "c"}, input: nil, want: false},
+		{allowedKeys: []string{"a", "b", "c"}, input: (map[string]any)(nil), want: true},
+	}
+
+	for _, tc := range cases {
+		tc := tc
+		t.Run(fmt.Sprintf("Validate_%v_%t", tc.input, tc.want), func(t *testing.T) {
+			v := KeysIn(tc.allowedKeys...)
+			assert.Equal(t, tc.want, v.Validate(&Context{
+				Value: tc.input,
+			}))
+		})
+	}
+}