Add handling of custom types

can add custom type handling, example: sql driver Valuer
can override any base data type like string or int ( I'd be carefull about that, but you can )

README.md

@@ -12,7 +12,8 @@ It has the following **unique** features:
 
 -   Cross Field and Cross Struct validations.  
 -   Slice, Array and Map diving, which allows any or all levels of a multidimensional field to be validated.  
--   Handles type interface by determining it's underlying type prior to validation.  
+-   Handles type interface by determining it's underlying type prior to validation.
+-   Handles custom field types such as sql driver Valuer see [Valuer](https://golang.org/src/database/sql/driver/types.go?s=1210:1293#L29)
 
 Installation
 ------------
@@ -35,6 +36,8 @@ Usage and documentation
 Please see http://godoc.org/gopkg.in/bluesuncorp/validator.v6 for detailed usage docs.
 
 ##### Examples:
+
+Struct & Field validation
 ```go
 package main
 
@@ -130,6 +133,76 @@ func validateField() {
 }
 ```
 
+Custom Field Type
+```go
+package main
+
+import (
+	"errors"
+	"fmt"
+	"reflect"
+
+	sql "database/sql/driver"
+
+	"gopkg.in/bluesuncorp/validator.v6"
+)
+
+var validate *validator.Validate
+
+type valuer struct {
+	Name string
+}
+
+func (v valuer) Value() (sql.Value, error) {
+
+	if v.Name == "errorme" {
+		return nil, errors.New("some kind of error")
+	}
+
+	if v.Name == "blankme" {
+		return "", nil
+	}
+
+	if len(v.Name) == 0 {
+		return nil, nil
+	}
+
+	return v.Name, nil
+}
+
+func main() {
+
+	customTypes := map[reflect.Type]validator.CustomTypeFunc{}
+	customTypes[reflect.TypeOf((*sql.Valuer)(nil))] = ValidateValuerType
+	customTypes[reflect.TypeOf(valuer{})] = ValidateValuerType
+
+	config := validator.Config{
+		TagName:         "validate",
+		ValidationFuncs: validator.BakedInValidators,
+		CustomTypeFuncs: customTypes,
+	}
+
+	validate = validator.New(config)
+
+	validateCustomFieldType()
+}
+
+func validateCustomFieldType() {
+	val := valuer{
+		Name: "blankme",
+	}
+
+	errs := validate.Field(val, "required")
+	if errs != nil {
+		fmt.Println(errs) // output: Key: "" Error:Field validation for "" failed on the "required" tag
+		return
+	}
+
+	// all ok
+}
+
+```
+
 Benchmarks
 ------
 ###### Run on MacBook Pro (Retina, 15-inch, Late 2013) 2.6 GHz Intel Core i7 16 GB 1600 MHz DDR3
@@ -139,18 +212,22 @@ hurt parallel performance too much.
 ```go
 $ go test -cpu=4 -bench=. -benchmem=true
 PASS
-BenchmarkFieldSuccess-4					 5000000	       326 ns/op	      16 B/op	       1 allocs/op
+BenchmarkFieldSuccess-4	 					 5000000	       318 ns/op	      16 B/op	       1 allocs/op
-BenchmarkFieldFailure-4					 5000000	       327 ns/op	      16 B/op	       1 allocs/op
+BenchmarkFieldFailure-4	 					 5000000	       316 ns/op	      16 B/op	       1 allocs/op
-BenchmarkFieldOrTagSuccess-4			  500000	      2738 ns/op	      20 B/op	       2 allocs/op
+BenchmarkFieldCustomTypeSuccess-4	 		 3000000	       492 ns/op	      32 B/op	       2 allocs/op
-BenchmarkFieldOrTagFailure-4			 1000000	      1341 ns/op	     384 B/op	       6 allocs/op
+BenchmarkFieldCustomTypeFailure-4	 		 2000000	       843 ns/op	     416 B/op	       6 allocs/op
-BenchmarkStructSimpleSuccess-4			 1000000	      1282 ns/op	      24 B/op	       3 allocs/op
+BenchmarkFieldOrTagSuccess-4	  			  500000	      2384 ns/op	      20 B/op	       2 allocs/op
-BenchmarkStructSimpleFailure-4			 1000000	      1870 ns/op	     529 B/op	      11 allocs/op
+BenchmarkFieldOrTagFailure-4	 			 1000000	      1295 ns/op	     384 B/op	       6 allocs/op
-BenchmarkStructSimpleSuccessParallel-4	 5000000	       348 ns/op	      24 B/op	       3 allocs/op
+BenchmarkStructSimpleSuccess-4	 			 1000000	      1175 ns/op	      24 B/op	       3 allocs/op
-BenchmarkStructSimpleFailureParallel-4	 2000000	       807 ns/op	     529 B/op	      11 allocs/op
+BenchmarkStructSimpleFailure-4	 			 1000000	      1822 ns/op	     529 B/op	      11 allocs/op
-BenchmarkStructComplexSuccess-4			  200000	      8081 ns/op	     368 B/op	      30 allocs/op
+BenchmarkStructSimpleCustomTypeSuccess-4	 1000000	      1302 ns/op	      56 B/op	       5 allocs/op
-BenchmarkStructComplexFailure-4			  100000	     12418 ns/op	    2861 B/op	      72 allocs/op
+BenchmarkStructSimpleCustomTypeFailure-4	 1000000	      1847 ns/op	     577 B/op	      13 allocs/op
-BenchmarkStructComplexSuccessParallel-4	  500000	      2249 ns/op	     369 B/op	      30 allocs/op
+BenchmarkStructSimpleSuccessParallel-4	 	 5000000	       339 ns/op	      24 B/op	       3 allocs/op
-BenchmarkStructComplexFailureParallel-4	  300000	      5183 ns/op	    2863 B/op	      72 allocs/op
+BenchmarkStructSimpleFailureParallel-4	 	 2000000	       733 ns/op	     529 B/op	      11 allocs/op
+BenchmarkStructComplexSuccess-4	  			  200000	      7104 ns/op	     368 B/op	      30 allocs/op
+BenchmarkStructComplexFailure-4	  			  100000	     11996 ns/op	    2861 B/op	      72 allocs/op
+BenchmarkStructComplexSuccessParallel-4	 	 1000000	      2252 ns/op	     368 B/op	      30 allocs/op
+BenchmarkStructComplexFailureParallel-4	  	  300000	      4691 ns/op	    2862 B/op	      72 allocs/op
 ```
 
 How to Contribute

benchmarks_test.go

@@ -1,6 +1,10 @@
 package validator
 
-import "testing"
+import (
+	sql "database/sql/driver"
+	"reflect"
+	"testing"
+)
 
 func BenchmarkFieldSuccess(b *testing.B) {
 	for n := 0; n < b.N; n++ {
@@ -14,6 +18,38 @@ func BenchmarkFieldFailure(b *testing.B) {
 	}
 }
 
+func BenchmarkFieldCustomTypeSuccess(b *testing.B) {
+
+	customTypes := map[reflect.Type]CustomTypeFunc{}
+	customTypes[reflect.TypeOf((*sql.Valuer)(nil))] = ValidateValuerType
+	customTypes[reflect.TypeOf(valuer{})] = ValidateValuerType
+
+	validate := New(Config{TagName: "validate", ValidationFuncs: BakedInValidators, CustomTypeFuncs: customTypes})
+
+	val := valuer{
+		Name: "1",
+	}
+
+	for n := 0; n < b.N; n++ {
+		validate.Field(val, "len=1")
+	}
+}
+
+func BenchmarkFieldCustomTypeFailure(b *testing.B) {
+
+	customTypes := map[reflect.Type]CustomTypeFunc{}
+	customTypes[reflect.TypeOf((*sql.Valuer)(nil))] = ValidateValuerType
+	customTypes[reflect.TypeOf(valuer{})] = ValidateValuerType
+
+	validate := New(Config{TagName: "validate", ValidationFuncs: BakedInValidators, CustomTypeFuncs: customTypes})
+
+	val := valuer{}
+
+	for n := 0; n < b.N; n++ {
+		validate.Field(val, "len=1")
+	}
+}
+
 func BenchmarkFieldOrTagSuccess(b *testing.B) {
 	for n := 0; n < b.N; n++ {
 		validate.Field("rgba(0,0,0,1)", "rgb|rgba")
@@ -54,6 +90,52 @@ func BenchmarkStructSimpleFailure(b *testing.B) {
 	}
 }
 
+func BenchmarkStructSimpleCustomTypeSuccess(b *testing.B) {
+
+	customTypes := map[reflect.Type]CustomTypeFunc{}
+	customTypes[reflect.TypeOf((*sql.Valuer)(nil))] = ValidateValuerType
+	customTypes[reflect.TypeOf(valuer{})] = ValidateValuerType
+
+	validate := New(Config{TagName: "validate", ValidationFuncs: BakedInValidators, CustomTypeFuncs: customTypes})
+
+	val := valuer{
+		Name: "1",
+	}
+
+	type Foo struct {
+		Valuer   valuer `validate:"len=1"`
+		IntValue int    `validate:"min=5,max=10"`
+	}
+
+	validFoo := &Foo{Valuer: val, IntValue: 7}
+
+	for n := 0; n < b.N; n++ {
+		validate.Struct(validFoo)
+	}
+}
+
+func BenchmarkStructSimpleCustomTypeFailure(b *testing.B) {
+
+	customTypes := map[reflect.Type]CustomTypeFunc{}
+	customTypes[reflect.TypeOf((*sql.Valuer)(nil))] = ValidateValuerType
+	customTypes[reflect.TypeOf(valuer{})] = ValidateValuerType
+
+	validate := New(Config{TagName: "validate", ValidationFuncs: BakedInValidators, CustomTypeFuncs: customTypes})
+
+	val := valuer{}
+
+	type Foo struct {
+		Valuer   valuer `validate:"len=1"`
+		IntValue int    `validate:"min=5,max=10"`
+	}
+
+	validFoo := &Foo{Valuer: val, IntValue: 3}
+
+	for n := 0; n < b.N; n++ {
+		validate.Struct(validFoo)
+	}
+}
+
 func BenchmarkStructSimpleSuccessParallel(b *testing.B) {
 
 	type Foo struct {

examples/simple.go

@@ -1,7 +1,11 @@
 package main
 
 import (
+	"errors"
 	"fmt"
+	"reflect"
+
+	sql "database/sql/driver"
 
 	"gopkg.in/bluesuncorp/validator.v6"
 )
@@ -90,3 +94,57 @@ func validateField() {
 
 	// email ok, move on
 }
+
+var validate2 *validator.Validate
+
+type valuer struct {
+	Name string
+}
+
+func (v valuer) Value() (sql.Value, error) {
+
+	if v.Name == "errorme" {
+		return nil, errors.New("some kind of error")
+	}
+
+	if v.Name == "blankme" {
+		return "", nil
+	}
+
+	if len(v.Name) == 0 {
+		return nil, nil
+	}
+
+	return v.Name, nil
+}
+
+func main2() {
+
+	customTypes := map[reflect.Type]validator.CustomTypeFunc{}
+	customTypes[reflect.TypeOf((*sql.Valuer)(nil))] = ValidateValuerType
+	customTypes[reflect.TypeOf(valuer{})] = ValidateValuerType
+
+	config := validator.Config{
+		TagName:         "validate",
+		ValidationFuncs: validator.BakedInValidators,
+		CustomTypeFuncs: customTypes,
+	}
+
+	validate2 = validator.New(config)
+
+	validateCustomFieldType()
+}
+
+func validateCustomFieldType() {
+	val := valuer{
+		Name: "blankme",
+	}
+
+	errs := validate2.Field(val, "required")
+	if errs != nil {
+		fmt.Println(errs) // output: Key: "" Error:Field validation for "" failed on the "required" tag
+		return
+	}
+
+	// all ok
+}

validator.go

@@ -45,7 +45,7 @@ var (
 
 // returns new ValidationErrors to the pool
 func newValidationErrors() interface{} {
-	return map[string]*FieldError{}
+	return ValidationErrors{}
 }
 
 type tagCache struct {
@@ -81,8 +81,15 @@ type Validate struct {
 type Config struct {
 	TagName         string
 	ValidationFuncs map[string]Func
+	CustomTypeFuncs map[reflect.Type]CustomTypeFunc
+	hasCustomFuncs  bool
 }
 
+// CustomTypeFunc allows for overriding or adding custom field type handler functions
+// field = field value of the type to return a value to be validated
+// example Valuer from sql drive see https://golang.org/src/database/sql/driver/types.go?s=1210:1293#L29
+type CustomTypeFunc func(field reflect.Value) interface{}
+
 // Func accepts all values needed for file and cross field validation
 // topStruct     = top level struct when validating by struct otherwise nil
 // currentStruct = current level struct when validating by struct otherwise optional comparison value
@@ -124,6 +131,11 @@ type FieldError struct {
 
 // New creates a new Validate instance for use.
 func New(config Config) *Validate {
+
+	if config.CustomTypeFuncs != nil && len(config.CustomTypeFuncs) > 0 {
+		config.hasCustomFuncs = true
+	}
+
 	return &Validate{config: config}
 }
 
@@ -150,7 +162,7 @@ func (v *Validate) RegisterValidation(key string, f Func) error {
 // validate Array, Slice and maps fields which may contain more than one error
 func (v *Validate) Field(field interface{}, tag string) ValidationErrors {
 
-	errs := errsPool.Get().(map[string]*FieldError)
+	errs := errsPool.Get().(ValidationErrors)
 	fieldVal := reflect.ValueOf(field)
 
 	v.traverseField(fieldVal, fieldVal, fieldVal, "", errs, false, tag, "")
@@ -168,7 +180,7 @@ func (v *Validate) Field(field interface{}, tag string) ValidationErrors {
 // validate Array, Slice and maps fields which may contain more than one error
 func (v *Validate) FieldWithValue(val interface{}, field interface{}, tag string) ValidationErrors {
 
-	errs := errsPool.Get().(map[string]*FieldError)
+	errs := errsPool.Get().(ValidationErrors)
 	topVal := reflect.ValueOf(val)
 
 	v.traverseField(topVal, topVal, reflect.ValueOf(field), "", errs, false, tag, "")
@@ -184,7 +196,7 @@ func (v *Validate) FieldWithValue(val interface{}, field interface{}, tag string
 // Struct validates a structs exposed fields, and automatically validates nested structs, unless otherwise specified.
 func (v *Validate) Struct(current interface{}) ValidationErrors {
 
-	errs := errsPool.Get().(map[string]*FieldError)
+	errs := errsPool.Get().(ValidationErrors)
 	sv := reflect.ValueOf(current)
 
 	v.tranverseStruct(sv, sv, sv, "", errs, true)
@@ -316,6 +328,13 @@ func (v *Validate) traverseField(topStruct reflect.Value, currentStruct reflect.
 
 			if kind == reflect.Struct {
 
+				if v.config.hasCustomFuncs {
+					if fn, ok := v.config.CustomTypeFuncs[typ]; ok {
+						v.traverseField(topStruct, currentStruct, reflect.ValueOf(fn(current)), errPrefix, errs, isStructField, tag, name)
+						return
+					}
+				}
+
 				// required passed validation above so stop here
 				// if only validating the structs existance.
 				if strings.Contains(tag, structOnlyTag) {
@@ -334,6 +353,13 @@ func (v *Validate) traverseField(topStruct reflect.Value, currentStruct reflect.
 		}
 	}
 
+	if v.config.hasCustomFuncs {
+		if fn, ok := v.config.CustomTypeFuncs[typ]; ok {
+			v.traverseField(topStruct, currentStruct, reflect.ValueOf(fn(current)), errPrefix, errs, isStructField, tag, name)
+			return
+		}
+	}
+
 	tags, isCached := tagsCache.Get(tag)
 
 	if !isCached {

validator_test.go

@@ -1,11 +1,14 @@
 package validator
 
 import (
+	"errors"
 	"fmt"
 	"reflect"
 	"testing"
 	"time"
 
+	sql "database/sql/driver"
+
 	. "gopkg.in/bluesuncorp/assert.v1"
 )
 
@@ -119,6 +122,131 @@ func AssertError(t *testing.T, errs ValidationErrors, key, field, expectedTag st
 	EqualSkip(t, 2, val.Tag, expectedTag)
 }
 
+type valuer struct {
+	Name string
+}
+
+func (v valuer) Value() (sql.Value, error) {
+
+	if v.Name == "errorme" {
+		return nil, errors.New("some kind of error")
+	}
+
+	if len(v.Name) == 0 {
+		return nil, nil
+	}
+
+	return v.Name, nil
+}
+
+type MadeUpCustomType struct {
+	FirstName string
+	LastName  string
+}
+
+func ValidateCustomType(field reflect.Value) interface{} {
+	if cust, ok := field.Interface().(MadeUpCustomType); ok {
+
+		if len(cust.FirstName) == 0 || len(cust.LastName) == 0 {
+			return ""
+		}
+
+		return cust.FirstName + " " + cust.LastName
+	}
+
+	return ""
+}
+
+func OverrideIntTypeForSomeReason(field reflect.Value) interface{} {
+
+	if i, ok := field.Interface().(int); ok {
+		if i == 1 {
+			return "1"
+		}
+
+		if i == 2 {
+			return "12"
+		}
+	}
+
+	return ""
+}
+
+type CustomMadeUpStruct struct {
+	MadeUp        MadeUpCustomType `validate:"required"`
+	OverriddenInt int              `validate:"gt=1"`
+}
+
+func ValidateValuerType(field reflect.Value) interface{} {
+	if valuer, ok := field.Interface().(sql.Valuer); ok {
+		val, err := valuer.Value()
+		if err != nil {
+			// handle the error how you want
+			return nil
+		}
+
+		return val
+	}
+
+	return nil
+}
+
+func TestSQLValueValidation(t *testing.T) {
+
+	customTypes := map[reflect.Type]CustomTypeFunc{}
+	customTypes[reflect.TypeOf((*sql.Valuer)(nil))] = ValidateValuerType
+	customTypes[reflect.TypeOf(valuer{})] = ValidateValuerType
+	customTypes[reflect.TypeOf(MadeUpCustomType{})] = ValidateCustomType
+	customTypes[reflect.TypeOf(1)] = OverrideIntTypeForSomeReason
+
+	validate := New(Config{TagName: "validate", ValidationFuncs: BakedInValidators, CustomTypeFuncs: customTypes})
+
+	val := valuer{
+		Name: "",
+	}
+
+	errs := validate.Field(val, "required")
+	NotEqual(t, errs, nil)
+	AssertError(t, errs, "", "", "required")
+
+	val.Name = "Valid Name"
+	errs = validate.Field(val, "required")
+	Equal(t, errs, nil)
+
+	val.Name = "errorme"
+
+	PanicMatches(t, func() { errs = validate.Field(val, "required") }, "SQL Driver Valuer error: some kind of error")
+
+	type myValuer valuer
+
+	myVal := valuer{
+		Name: "",
+	}
+
+	errs = validate.Field(myVal, "required")
+	NotEqual(t, errs, nil)
+	AssertError(t, errs, "", "", "required")
+
+	cust := MadeUpCustomType{
+		FirstName: "Joey",
+		LastName:  "Bloggs",
+	}
+
+	c := CustomMadeUpStruct{MadeUp: cust, OverriddenInt: 2}
+
+	errs = validate.Struct(c)
+	Equal(t, errs, nil)
+
+	c.MadeUp.FirstName = ""
+	c.OverriddenInt = 1
+
+	errs = validate.Struct(c)
+	NotEqual(t, errs, nil)
+	Equal(t, len(errs), 2)
+	AssertError(t, errs, "CustomMadeUpStruct.MadeUp", "MadeUp", "required")
+	AssertError(t, errs, "CustomMadeUpStruct.OverriddenInt", "OverriddenInt", "gt")
+}
+
 func TestMACValidation(t *testing.T) {
 	tests := []struct {
 		param    string