Add EachWithOptions for Validating Arrays of Objects (#12)

* adding possibility to validate array of objects

* fixed a type i test validate

Author: kthehatter

validator/range.go

@@ -109,3 +109,34 @@ func Each(validatorFunc ValidatorFunc) ValidatorFunc {
 		return nil
 	}
 }
+
+// EachWithOptions applies a set of validation options to each element in a slice or array, returning the first error
+func EachWithOptions(options []ValidationOption) ValidatorFunc {
+	return func(value interface{}) error {
+		if value == nil {
+			return fmt.Errorf("value must be a non-nil slice or array")
+		}
+		v := reflect.ValueOf(value)
+		if v.Kind() != reflect.Slice && v.Kind() != reflect.Array {
+			return fmt.Errorf("value must be a slice or array, got %T", value)
+		}
+		if v.Len() == 0 {
+			return nil
+		}
+		for i := 0; i < v.Len(); i++ {
+			elem := v.Index(i).Interface()
+			nestedBody, ok := elem.(map[string]interface{})
+			if !ok {
+				if reflect.TypeOf(elem).Kind() == reflect.Struct {
+					nestedBody = StructToMap(elem)
+				} else {
+					return fmt.Errorf("element at index %d must be an object, got %T", i, elem)
+				}
+			}
+			if err := Validate(nestedBody, options); err != nil {
+				return fmt.Errorf("element at index %d: %v", i, err)
+			}
+		}
+		return nil
+	}
+}

validator/range_test.go

@@ -144,3 +144,114 @@ func TestEach(t *testing.T) {
 		require.EqualError(t, err, "value must be a slice or array")
 	})
 }
+
+func TestEachWithOptions(t *testing.T) {
+	nestedOptions := []ValidationOption{
+		{
+			Key:        "name",
+			IsOptional: false,
+			Validators: []Validator{
+				CreateValidator(IsNotEmpty, "name is required"),
+				CreateValidator(IsString, "value must be a string"),
+			},
+		},
+		{
+			Key:        "value",
+			IsOptional: false,
+			Validators: []Validator{
+				CreateValidator(IsNotEmpty, "value is required"),
+			},
+		},
+	}
+
+	tests := []struct {
+		name     string
+		input    interface{}
+		expected error
+	}{
+		{
+			name: "valid array of maps",
+			input: []interface{}{
+				map[string]interface{}{"name": "color", "value": "red"},
+				map[string]interface{}{"name": "size", "value": "M"},
+			},
+			expected: nil,
+		},
+		{
+			name: "invalid array - missing required field",
+			input: []interface{}{
+				map[string]interface{}{"name": "color", "value": "red"},
+				map[string]interface{}{"value": "M"},
+			},
+			expected: errors.New("element at index 1: name is required"),
+		},
+		{
+			name: "invalid array - wrong type",
+			input: []interface{}{
+				map[string]interface{}{"name": "color", "value": "red"},
+				map[string]interface{}{"name": 123, "value": "M"},
+			},
+			expected: errors.New("element at index 1: value must be a string"),
+		},
+		{
+			name:     "empty array",
+			input:    []interface{}{},
+			expected: nil,
+		},
+		{
+			name:     "nil array",
+			input:    nil,
+			expected: errors.New("value must be a non-nil slice or array"),
+		},
+		{
+			name:     "not an array",
+			input:    "not an array",
+			expected: errors.New("value must be a slice or array, got string"),
+		},
+		{
+			name: "valid array of structs",
+			input: []interface{}{
+				struct {
+					Name  string `json:"name"`
+					Value string `json:"value"`
+				}{Name: "color", Value: "red"},
+				struct {
+					Name  string `json:"name"`
+					Value string `json:"value"`
+				}{Name: "size", Value: "M"},
+			},
+			expected: nil,
+		},
+		{
+			name: "invalid element type",
+			input: []interface{}{
+				"not a map or struct",
+			},
+			expected: errors.New("element at index 0 must be an object, got string"),
+		},
+		{
+			name: "json with mixed case keys",
+			input: []interface{}{
+				map[string]interface{}{
+					"name":  "ahmed",
+					"Name":  123,
+					"value": "test",
+				},
+			},
+			expected: nil,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			validator := EachWithOptions(nestedOptions)
+			err := validator(tt.input)
+			if tt.expected == nil {
+				require.NoError(t, err, "expected no error")
+			} else {
+				require.Error(t, err, "expected an error")
+				require.Equal(t, tt.expected.Error(), err.Error(), "error message mismatch")
+			}
+		})
+	}
+}

validator/validator.go

@@ -1,6 +1,10 @@
 package validator
 
-import "fmt"
+import (
+	"fmt"
+	"reflect"
+	"strings"
+)
 
 // ValidatorFunc is a function that validates a field and returns an error if validation fails.
 type ValidatorFunc func(value interface{}) error
@@ -33,6 +37,11 @@ func Validate(body map[string]interface{}, options []ValidationOption) error {
 			continue
 		}
 
+		// Check if the field is required but missing *before* running validators
+		if !option.IsOptional && !exists {
+			return fmt.Errorf("%s is required", option.Key)
+		}
+
 		// Apply transformations
 		if exists {
 			for _, transformer := range option.Transformers {
@@ -75,3 +84,28 @@ func CreateValidator(fn ValidatorFunc, message string) Validator {
 		Message: message,
 	}
 }
+
+// StructToMap converts a struct to a map[string]interface{} for validation
+func StructToMap(obj interface{}) map[string]interface{} {
+	result := make(map[string]interface{})
+	v := reflect.ValueOf(obj)
+	t := reflect.TypeOf(obj)
+
+	for i := range v.NumField() {
+		field := t.Field(i)
+		// Use the json tag if present, otherwise fall back to field name
+		jsonTag := field.Tag.Get("json")
+		key := field.Name
+		if jsonTag != "" {
+			// Split on "," to handle options like "omitempty"
+			if parts := strings.Split(jsonTag, ","); len(parts) > 0 {
+				key = parts[0]
+			}
+		}
+		// Only process exported fields
+		if field.PkgPath == "" { // PkgPath is empty for exported fields
+			result[key] = v.Field(i).Interface()
+		}
+	}
+	return result
+}

validator/validator_test.go

@@ -78,7 +78,7 @@ func TestValidate(t *testing.T) {
 				"username": "user123",
 				"password": "password123",
 			},
-			errors.New("Email is required"),
+			errors.New("email is required"),
 		},
 		{
 			"invalid email",