feat(binding): Add global default function

Change-Id: I7fd43d85cd50ebe7cbe7c2ba0f89b4261b761507

binding/bind.go

@@ -72,7 +72,7 @@ func (b *Binding) Bind(structPointer interface{}, req *http.Request, pathParams
 	return err
 }
 
-// Validate validates whether the fields of v is valid.
+// Validate validates whether the fields of value is valid.
 func (b *Binding) Validate(value interface{}) error {
 	return b.vd.Validate(value)
 }

binding/default.go

@@ -0,0 +1,42 @@
+package binding
+
+import "net/http"
+
+var defaultBinding = New(nil)
+
+// Default returns the default binding.
+// NOTE:
+//  path tag name is 'path';
+//  query tag name is 'query';
+//  header tag name is 'header';
+//  cookie tag name is 'cookie';
+//  rawbody tag name is 'rawbody';
+//  form tag name is 'form';
+//  validator tag name is 'vd';
+//  protobuf tag name is 'protobuf';
+//  json tag name is 'json'.
+func Default() *Binding {
+	return defaultBinding
+}
+
+// SetErrorFactory customizes the factory of validation error.
+// NOTE:
+//  If errFactory==nil, the default is used
+func SetErrorFactory(bindErrFactory, validatingErrFactory func(failField, msg string) error) {
+	defaultBinding.SetErrorFactory(bindErrFactory, validatingErrFactory)
+}
+
+// BindAndValidate binds the request parameters and validates them if needed.
+func BindAndValidate(structPointer interface{}, req *http.Request, pathParams PathParams) error {
+	return defaultBinding.BindAndValidate(structPointer, req, pathParams)
+}
+
+// Bind binds the request parameters.
+func Bind(structPointer interface{}, req *http.Request, pathParams PathParams) error {
+	return defaultBinding.Bind(structPointer, req, pathParams)
+}
+
+// Validate validates whether the fields of value is valid.
+func Validate(value interface{}) error {
+	return defaultBinding.Validate(value)
+}