issue-#1

add alpha validation function + Test code
add alphanumeric validation function + Test code

baked_in.go

@@ -1,16 +1,46 @@
 package validator
 
 import (
-	"log"
+	"fmt"
 	"reflect"
 	"strconv"
 )
 
+// BakedInValidators is the map of ValidationFunc used internally
+// but can be used with any new Validator if desired
 var BakedInValidators = map[string]ValidationFunc{
 	"required": required,
 	"len":      length,
 	"min":      min,
 	"max":      max,
+	"alpha":    alpha,
+	"alphanum": alphanum,
+}
+
+func alphanum(field interface{}, param string) bool {
+
+	st := reflect.ValueOf(field)
+
+	switch st.Kind() {
+
+	case reflect.String:
+		return alphaNumericRegex.MatchString(field.(string))
+	default:
+		panic(fmt.Sprintf("Bad field type %T", field))
+	}
+}
+
+func alpha(field interface{}, param string) bool {
+
+	st := reflect.ValueOf(field)
+
+	switch st.Kind() {
+
+	case reflect.String:
+		return alphaRegex.MatchString(field.(string))
+	default:
+		panic(fmt.Sprintf("Bad field type %T", field))
+	}
 }
 
 func required(field interface{}, param string) bool {
@@ -62,8 +92,7 @@ func length(field interface{}, param string) bool {
 		return st.Float() == p
 
 	default:
-		log.Fatalf("Bad field type for Input Param %s for %s\n", param, field)
-		return false
+		panic(fmt.Sprintf("Bad field type for Input Param %s for %s\n", param, field))
 	}
 }
 
@@ -103,8 +132,7 @@ func min(field interface{}, param string) bool {
 		return st.Float() >= p
 
 	default:
-		log.Fatalf("Bad field type for Input Param %s for %s\n", param, field)
-		return false
+		panic(fmt.Sprintf("Bad field type for Input Param %s for %s\n", param, field))
 	}
 }
 
@@ -144,8 +172,7 @@ func max(field interface{}, param string) bool {
 		return st.Float() <= p
 
 	default:
-		log.Fatalf("Bad field type for Input Param %s for %s\n", param, field)
-		return false
+		panic(fmt.Sprintf("Bad field type for Input Param %s for %s\n", param, field))
 	}
 }
 
@@ -156,7 +183,7 @@ func asInt(param string) int64 {
 	i, err := strconv.ParseInt(param, 0, 64)
 
 	if err != nil {
-		log.Fatalf("Bad Input Param %s\n", param)
+		panic(fmt.Sprintf("Bad Input Param %s\n", param))
 	}
 
 	return i
@@ -169,7 +196,7 @@ func asUint(param string) uint64 {
 	i, err := strconv.ParseUint(param, 0, 64)
 
 	if err != nil {
-		log.Fatalf("Bad Input Param %s\n", param)
+		panic(fmt.Sprintf("Bad Input Param %s\n", param))
 	}
 
 	return i
@@ -182,7 +209,7 @@ func asFloat(param string) float64 {
 	i, err := strconv.ParseFloat(param, 64)
 
 	if err != nil {
-		log.Fatalf("Bad Input Param %s\n", param)
+		panic(fmt.Sprintf("Bad Input Param %s\n", param))
 	}
 
 	return i

doc.go

@@ -132,6 +132,11 @@ Here is a list of the current built in validators:
 		a value (Determined by the required validator) then other validation
 		such as min or max won't run, but if a value is set validation will run.
 		(Usage: omitempty)
+	required
+		This validates that the value is not the data types default value.
+		For numbers ensures value is not zero. For strings ensures value is
+		not "". For slices, arrays, and maps, ensures the length is not zero.
+		(Usage: required)
 	len
 		For numbers, max will ensure that the value is
 		equal to the parameter given. For strings, it checks that
@@ -147,12 +152,12 @@ Here is a list of the current built in validators:
 		greater or equal to the parameter given. For strings, it checks that
 		the string length is at least that number of characters. For slices,
 		arrays, and maps, validates the number of items. (Usage: min=10)
-
-	required
-		This validates that the value is not the data types default value.
-		For numbers ensures value is not zero. For strings ensures value is
-		not "". For slices, arrays, and maps, ensures the length is not zero.
-		(Usage: required)
+	alpha
+		This validates that a strings value contains alpha characters only
+		(Usage: alpha)
+	alphanum
+		This validates that a strings value contains alphanumeric characters only
+		(Usage: alphanum)
 
 Validator notes:
 

regexes.go

@@ -0,0 +1,13 @@
+package validator
+
+import "regexp"
+
+const (
+	alphaRegexString        string = "^[a-zA-Z]+$"
+	alphaNumericRegexString string = "^[a-zA-Z0-9]+$"
+)
+
+var (
+	alphaRegex        = regexp.MustCompile(alphaRegexString)
+	alphaNumericRegex = regexp.MustCompile(alphaNumericRegexString)
+)

validator.go

@@ -279,7 +279,7 @@ func (v *Validator) validateFieldByNameAndTag(f interface{}, name string, tag st
 
 	switch valueField.Kind() {
 
-	case reflect.Struct, reflect.Invalid:
+	case reflect.Struct, reflect.Interface, reflect.Invalid:
 		panic("Invalid field passed to ValidateFieldWithTag")
 	}
 

validator_test.go

@@ -113,6 +113,32 @@ func AssertMapFieldError(s map[string]*validator.FieldValidationError, field str
 	c.Assert(val.ErrorTag, Equals, expectedTag)
 }
 
+func (ms *MySuite) TestAlphaNumeric(c *C) {
+
+	s := "abcd123"
+	err := validator.ValidateFieldByTag(s, "alphanum")
+	c.Assert(err, IsNil)
+
+	s = "abc!23"
+	err = validator.ValidateFieldByTag(s, "alphanum")
+	c.Assert(err.Error(), Equals, "alphanum")
+
+	c.Assert(func() { validator.ValidateFieldByTag(1, "alphanum") }, PanicMatches, "Bad field type int")
+}
+
+func (ms *MySuite) TestAlpha(c *C) {
+
+	s := "abcd"
+	err := validator.ValidateFieldByTag(s, "alpha")
+	c.Assert(err, IsNil)
+
+	s = "abc1"
+	err = validator.ValidateFieldByTag(s, "alpha")
+	c.Assert(err.Error(), Equals, "alpha")
+
+	c.Assert(func() { validator.ValidateFieldByTag(1, "alpha") }, PanicMatches, "Bad field type int")
+}
+
 func (ms *MySuite) TestFlattening(c *C) {
 
 	tSuccess := &TestString{