From b308c8b0a9969044dfd06b3f09faa801577bb60a Mon Sep 17 00:00:00 2001
From: Suhas Karanth <sudo.suhas@gmail.com>
Date: Sat, 10 Mar 2018 08:35:08 +0530
Subject: [PATCH] fix(binding): Move validator engine getter inside interface

---
 README.md                                 |  8 ++++----
 binding/binding.go                        | 21 ++++-----------------
 binding/default_validator.go              |  9 +++++++++
 binding/validate_test.go                  |  4 ++--
 examples/custom-validation/server.go      |  8 ++++----
 examples/struct-lvl-validations/server.go |  8 ++++----
 6 files changed, 27 insertions(+), 31 deletions(-)

diff --git a/README.md b/README.md
index cc2d653a..d3f85fa9 100644
--- a/README.md
+++ b/README.md
@@ -564,11 +564,11 @@ func bookableDate(
 
 func main() {
 	route := gin.Default()
-	v := binding.ValidatorEngine()
-	if v == nil {
-		panic("validator engine is nil")
+
+	if v, ok := binding.Validator.Engine().(*validator.Validate); ok {
+		v.RegisterValidation("bookabledate", bookableDate)
 	}
-	v.RegisterValidation("bookabledate", bookableDate)
+
 	route.GET("/bookable", getBookable)
 	route.Run(":8085")
 }
diff --git a/binding/binding.go b/binding/binding.go
index 20ee6f86..646eb80a 100644
--- a/binding/binding.go
+++ b/binding/binding.go
@@ -6,8 +6,6 @@ package binding
 
 import (
 	"net/http"
-
-	validator "gopkg.in/go-playground/validator.v8"
 )
 
 const (
@@ -42,6 +40,10 @@ type StructValidator interface {
 	// If the struct is not valid or the validation itself fails, a descriptive error should be returned.
 	// Otherwise nil must be returned.
 	ValidateStruct(interface{}) error
+
+	// Engine returns the underlying validator engine which powers the
+	// StructValidator implementation.
+	Engine() interface{}
 }
 
 // Validator is the default validator which implements the StructValidator
@@ -89,18 +91,3 @@ func validate(obj interface{}) error {
 	}
 	return Validator.ValidateStruct(obj)
 }
-
-// ValidatorEngine returns the underlying validator engine which powers the
-// default Validator instance. This is useful if you want to register custom
-// validations or struct level validations. See validator GoDoc for more info -
-// https://godoc.org/gopkg.in/go-playground/validator.v8
-func ValidatorEngine() *validator.Validate {
-	if Validator == nil {
-		return nil
-	}
-	if v, ok := Validator.(*defaultValidator); ok {
-		v.lazyinit()
-		return v.validate
-	}
-	return nil
-}
diff --git a/binding/default_validator.go b/binding/default_validator.go
index 19885f16..c67aa8a3 100644
--- a/binding/default_validator.go
+++ b/binding/default_validator.go
@@ -28,6 +28,15 @@ func (v *defaultValidator) ValidateStruct(obj interface{}) error {
 	return nil
 }
 
+// Engine returns the underlying validator engine which powers the default
+// Validator instance. This is useful if you want to register custom validations
+// or struct level validations. See validator GoDoc for more info -
+// https://godoc.org/gopkg.in/go-playground/validator.v8
+func (v *defaultValidator) Engine() interface{} {
+	v.lazyinit()
+	return v.validate
+}
+
 func (v *defaultValidator) lazyinit() {
 	v.once.Do(func() {
 		config := &validator.Config{TagName: "binding"}
diff --git a/binding/validate_test.go b/binding/validate_test.go
index 76ef89c3..cb76063c 100644
--- a/binding/validate_test.go
+++ b/binding/validate_test.go
@@ -218,8 +218,8 @@ func TestValidatorEngine(t *testing.T) {
 	// This validates that the function `notOne` matches
 	// the expected function signature by `defaultValidator`
 	// and by extension the validator library.
-	engine := ValidatorEngine()
-	assert.NotNil(t, engine)
+	engine, ok := Validator.Engine().(*validator.Validate)
+	assert.True(t, ok)
 
 	err := engine.RegisterValidation("notone", notOne)
 	// Check that we can register custom validation without error
diff --git a/examples/custom-validation/server.go b/examples/custom-validation/server.go
index 28cdad97..dea0c302 100644
--- a/examples/custom-validation/server.go
+++ b/examples/custom-validation/server.go
@@ -30,11 +30,11 @@ func bookableDate(
 
 func main() {
 	route := gin.Default()
-	v := binding.ValidatorEngine()
-	if v == nil {
-		panic("validator engine is nil")
+
+	if v, ok := binding.Validator.Engine().(*validator.Validate); ok {
+		v.RegisterValidation("bookabledate", bookableDate)
 	}
-	v.RegisterValidation("bookabledate", bookableDate)
+
 	route.GET("/bookable", getBookable)
 	route.Run(":8085")
 }
diff --git a/examples/struct-lvl-validations/server.go b/examples/struct-lvl-validations/server.go
index 2027940e..be807b78 100644
--- a/examples/struct-lvl-validations/server.go
+++ b/examples/struct-lvl-validations/server.go
@@ -42,11 +42,11 @@ func UserStructLevelValidation(v *validator.Validate, structLevel *validator.Str
 
 func main() {
 	route := gin.Default()
-	v := binding.ValidatorEngine()
-	if v == nil {
-		panic("validator engine is nil")
+
+	if v, ok := binding.Validator.Engine().(*validator.Validate); ok {
+		v.RegisterStructValidation(UserStructLevelValidation, User{})
 	}
-	v.RegisterStructValidation(UserStructLevelValidation, User{})
+
 	route.POST("/user", validateUser)
 	route.Run(":8085")
 }