Feat: implement email tag validation

README.md

@@ -47,6 +47,7 @@ The following validations will be implemented:
 - in (in): must be one of the following values
 - nin (not in): must not be one of the following values
 - required (required): is required
+- email (email): must be a valid email format (empty is valid for optional fields)
 
 The following table shows the validations and possible types, where "I" means "Implemented", "W" means "Will be implemented" and "-" means "Will not be implemented":
 
@@ -66,6 +67,7 @@ The following table shows the validations and possible types, where "I" means "I
 | in              | I      | W             | W       | W     | W     | W   | -    | W        |
 | nin             | W      | W             | W       | W     | W     | W   | -    | W        |
 | required        | I      | W             | W       | W     | W     | W   | W    | W        |
+| email           | I      | -             | -       | -     | -     | -   | -    | -        |
 
 # Steps to run the unit tests
 

_examples/email_test/test_email.go

@@ -0,0 +1,87 @@
+package main
+
+import (
+	"fmt"
+)
+
+type User struct {
+	Email1 string `validate:"required,email"`
+	Email2 string `validate:"email"`
+}
+
+func main() {
+	// Test case 1: Empty required email (should fail)
+	u1 := &User{
+		Email1: "",
+		Email2: "",
+	}
+	if errs := UserValidate(u1); len(errs) > 0 {
+		fmt.Printf("User1: %+v Errors: ", u1)
+		for _, err := range errs {
+			fmt.Printf("%s; ", err)
+		}
+		fmt.Println()
+	} else {
+		fmt.Printf("User1: %+v is valid\n", u1)
+	}
+
+	// Test case 2: Invalid required email (should fail)
+	u2 := &User{
+		Email1: "invalid.email",
+		Email2: "",
+	}
+	if errs := UserValidate(u2); len(errs) > 0 {
+		fmt.Printf("User2: %+v Errors: ", u2)
+		for _, err := range errs {
+			fmt.Printf("%s; ", err)
+		}
+		fmt.Println()
+	} else {
+		fmt.Printf("User2: %+v is valid\n", u2)
+	}
+
+	// Test case 3: Valid required email, empty optional email (should pass)
+	u3 := &User{
+		Email1: "valid@example.com",
+		Email2: "",
+	}
+	if errs := UserValidate(u3); len(errs) > 0 {
+		fmt.Printf("User3: %+v Errors: ", u3)
+		for _, err := range errs {
+			fmt.Printf("%s; ", err)
+		}
+		fmt.Println()
+	} else {
+		fmt.Printf("User3: %+v is valid\n", u3)
+	}
+
+	// Test case 4: Valid required email, valid optional email (should pass)
+	u4 := &User{
+		Email1: "user@domain.com",
+		Email2: "optional@test.org",
+	}
+	if errs := UserValidate(u4); len(errs) > 0 {
+		fmt.Printf("User4: %+v Errors: ", u4)
+		for _, err := range errs {
+			fmt.Printf("%s; ", err)
+		}
+		fmt.Println()
+	} else {
+		fmt.Printf("User4: %+v is valid\n", u4)
+	}
+
+	// Test case 5: Valid required email, invalid optional email (should fail)
+	u5 := &User{
+		Email1: "user@domain.com",
+		Email2: "invalid.email",
+	}
+	if errs := UserValidate(u5); len(errs) > 0 {
+		fmt.Printf("User5: %+v Errors: ", u5)
+		for _, err := range errs {
+			fmt.Printf("%s; ", err)
+		}
+		fmt.Println()
+	} else {
+		fmt.Printf("User5: %+v is valid\n", u5)
+	}
+}

tests/endtoend/string.go

@@ -11,12 +11,15 @@ type StringType struct {
 	FieldNeq    string `validate:"neq=cba"`
 	FieldNeqIC  string `validate:"neq_ignore_case=YeS"`
 	FieldIn     string `validate:"in=ab bc cd"`
+	EmailReq    string `validate:"required,email"`
+	EmailOpt    string `validate:"email"`
 }
 
 func string_tests() {
 	var expectedMsgErrors []string
 	var errs []error
 
+	// Test case 1: All validation failures including email
 	v := &StringType{
 		FieldEq:     "123",
 		FieldEqIC:   "abc",
@@ -25,6 +28,8 @@ func string_tests() {
 		FieldNeq:    "cba",
 		FieldNeqIC:  "yeS",
 		FieldIn:     "abc",
+		EmailReq:    "",           // Empty required email
+		EmailOpt:    "invalid",    // Invalid optional email
 	}
 	expectedMsgErrors = []string{
 		"FieldReq is required",
@@ -35,12 +40,15 @@ func string_tests() {
 		"FieldNeq must not be equal to 'cba'",
 		"FieldNeqIC must not be equal to 'yes'",
 		"FieldIn must be one of 'ab' 'bc' 'cd'",
+		"EmailReq is required",
+		"EmailOpt must be a valid email",
 	}
 	errs = StringTypeValidate(v)
 	if !expectedMsgErrorsOk(errs, expectedMsgErrors) {
 		log.Fatalf("error = %v, wantErr %v", errs, expectedMsgErrors)
 	}
 
+	// Test case 2: Invalid required email format
 	v = &StringType{
 		FieldReq:    "123",
 		FieldEq:     "aabbcc",
@@ -50,6 +58,48 @@ func string_tests() {
 		FieldNeq:    "ops",
 		FieldNeqIC:  "No",
 		FieldIn:     "bc",
+		EmailReq:    "invalid.email.format",  // Invalid required email
+		EmailOpt:    "",                      // Empty optional email (valid)
+	}
+	expectedMsgErrors = []string{
+		"EmailReq must be a valid email",
+	}
+	errs = StringTypeValidate(v)
+	if !expectedMsgErrorsOk(errs, expectedMsgErrors) {
+		log.Fatalf("error = %v, wantErr %v", errs, expectedMsgErrors)
+	}
+
+	// Test case 3: All valid including valid emails
+	v = &StringType{
+		FieldReq:    "123",
+		FieldEq:     "aabbcc",
+		FieldEqIC:   "yEs",
+		FieldMinMax: "12345678",
+		FieldLen:    "abcdefgh",
+		FieldNeq:    "ops",
+		FieldNeqIC:  "No",
+		FieldIn:     "bc",
+		EmailReq:    "user@example.com",      // Valid required email
+		EmailOpt:    "optional@test.org",     // Valid optional email
+	}
+	expectedMsgErrors = nil
+	errs = StringTypeValidate(v)
+	if !expectedMsgErrorsOk(errs, expectedMsgErrors) {
+		log.Fatalf("error = %v, wantErr %v", errs, expectedMsgErrors)
+	}
+
+	// Test case 4: Valid required email, empty optional email
+	v = &StringType{
+		FieldReq:    "123",
+		FieldEq:     "aabbcc",
+		FieldEqIC:   "yEs",
+		FieldMinMax: "12345678",
+		FieldLen:    "abcdefgh",
+		FieldNeq:    "ops",
+		FieldNeqIC:  "No",
+		FieldIn:     "bc",
+		EmailReq:    "required@domain.com",   // Valid required email
+		EmailOpt:    "",                      // Empty optional email (valid)
 	}
 	expectedMsgErrors = nil
 	errs = StringTypeValidate(v)

types/string_utils.go

@@ -1,7 +1,26 @@
 package types
 
-import "strings"
+import (
+	"regexp"
+	"strings"
+)
+
+// emailRegex is a pre-compiled regex for email validation
+// This avoids recompiling the regex on every validation call
+var emailRegex = regexp.MustCompile(`^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$`)
 
 func ToLower(str string) string {
 	return strings.ToLower(str)
 }
+
+// IsValidEmail validates if a string is a valid email format
+// Returns true for valid email format, false otherwise
+// Empty string returns true (for optional email fields)
+func IsValidEmail(email string) bool {
+	if email == "" {
+		return true // Empty email is valid for optional fields
+	}
+
+	// Use pre-compiled regex for better performance
+	return emailRegex.MatchString(email)
+}

types/string_utils_test.go

@@ -0,0 +1,80 @@
+package types
+
+import "testing"
+
+func TestIsValidEmail(t *testing.T) {
+	tests := []struct {
+		name  string
+		email string
+		want  bool
+	}{
+		{
+			name:  "empty email (valid for optional fields)",
+			email: "",
+			want:  true,
+		},
+		{
+			name:  "valid simple email",
+			email: "test@example.com",
+			want:  true,
+		},
+		{
+			name:  "valid email with subdomain",
+			email: "user@mail.example.com",
+			want:  true,
+		},
+		{
+			name:  "valid email with numbers and special chars",
+			email: "user123+tag@example.co.uk",
+			want:  true,
+		},
+		{
+			name:  "valid email with dots and underscores",
+			email: "first.last_name@domain.org",
+			want:  true,
+		},
+		{
+			name:  "invalid email without @",
+			email: "invalid.email.com",
+			want:  false,
+		},
+		{
+			name:  "invalid email without domain",
+			email: "user@",
+			want:  false,
+		},
+		{
+			name:  "invalid email without local part",
+			email: "@domain.com",
+			want:  false,
+		},
+		{
+			name:  "invalid email without TLD",
+			email: "user@domain",
+			want:  false,
+		},
+		{
+			name:  "invalid email with spaces",
+			email: "user @domain.com",
+			want:  false,
+		},
+		{
+			name:  "invalid email with multiple @",
+			email: "user@@domain.com",
+			want:  false,
+		},
+		{
+			name:  "invalid email with short TLD",
+			email: "user@domain.c",
+			want:  false,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := IsValidEmail(tt.email); got != tt.want {
+				t.Errorf("IsValidEmail(%q) = %v, want %v", tt.email, got, tt.want)
+			}
+		})
+	}
+}

validgen/get_test_elements_string_test.go

@@ -145,6 +145,19 @@ func TestGetTestElementsWithStringFields(t *testing.T) {
 				errorMessage:  "InField must be one of ' a ' ' b ' ' c '",
 			},
 		},
+		{
+			name: "Email validation",
+			args: args{
+				fieldName:       "EmailField",
+				fieldValidation: "email",
+			},
+			want: TestElements{
+				leftOperand:   "types.IsValidEmail(obj.EmailField)",
+				operator:      "==",
+				rightOperands: []string{`true`},
+				errorMessage:  "EmailField must be a valid email",
+			},
+		},
 	}
 
 	for _, tt := range tests {

validgen/parser_validation.go

@@ -34,6 +34,7 @@ func ParserValidation(fieldValidation string) (*Validation, error) {
 		"neq":             ONE_VALUE,
 		"neq_ignore_case": ONE_VALUE,
 		"in":              MANY_VALUES,
+		"email":           ZERO_VALUE,
 	}
 
 	validation, values, err := parserValidationString(fieldValidation)

validgen/parser_validation_test.go

@@ -95,6 +95,15 @@ func Test_ValidParserValidation(t *testing.T) {
 				Values:         []string{"a", "b", "c"},
 			},
 		},
+		{
+			name:       "email validation without value",
+			validation: "email",
+			want: &Validation{
+				Operation:      "email",
+				ExpectedValues: ZERO_VALUE,
+				Values:         []string{},
+			},
+		},
 	}
 
 	for _, tt := range tests {