Clean up comments, reorder types

pkg/util/validation/errors.go

@@ -25,6 +25,38 @@ import (
 	"github.com/davecgh/go-spew/spew"
 )
 
+// Error is an implementation of the 'error' interface, which represents a
+// validation error.
+type Error struct {
+	Type     ErrorType
+	Field    string
+	BadValue interface{}
+	Detail   string
+}
+
+var _ error = &Error{}
+
+// Error implements the error interface.
+func (v *Error) Error() string {
+	return fmt.Sprintf("%s: %s", v.Field, v.ErrorBody())
+}
+
+// ErrorBody returns the error message without the field name.  This is useful
+// for building nice-looking higher-level error reporting.
+func (v *Error) ErrorBody() string {
+	var s string
+	switch v.Type {
+	case ErrorTypeRequired, ErrorTypeTooLong:
+		s = spew.Sprintf("%s", v.Type)
+	default:
+		s = spew.Sprintf("%s '%+v'", v.Type, v.BadValue)
+	}
+	if len(v.Detail) != 0 {
+		s += fmt.Sprintf(", Details: %s", v.Detail)
+	}
+	return s
+}
+
 // ErrorType is a machine readable value providing more detail about why
 // a field is invalid.  These values are expected to match 1-1 with
 // CauseType in api/types.go.
@@ -32,30 +64,35 @@ type ErrorType string
 
 // TODO: These values are duplicated in api/types.go, but there's a circular dep.  Fix it.
 const (
-	// ErrorType is used to report failure to find a requested value
-	// (e.g. looking up an ID).
+	// ErrorTypeNotFound is used to report failure to find a requested value
+	// (e.g. looking up an ID).  See NewFieldNotFound.
 	ErrorTypeNotFound ErrorType = "FieldValueNotFound"
 	// ErrorTypeRequired is used to report required values that are not
-	// provided (e.g. empty strings, null values, or empty arrays).
+	// provided (e.g. empty strings, null values, or empty arrays).  See
+	// NewFieldRequired.
 	ErrorTypeRequired ErrorType = "FieldValueRequired"
 	// ErrorTypeDuplicate is used to report collisions of values that must be
-	// unique (e.g. unique IDs).
+	// unique (e.g. unique IDs).  See NewFieldDuplicate.
 	ErrorTypeDuplicate ErrorType = "FieldValueDuplicate"
 	// ErrorTypeInvalid is used to report malformed values (e.g. failed regex
-	// match).
+	// match, too long, out of bounds).  See NewFieldInvalid.
 	ErrorTypeInvalid ErrorType = "FieldValueInvalid"
 	// ErrorTypeNotSupported is used to report valid (as per formatting rules)
-	// values that can not be handled (e.g. an enumerated string).
+	// values that can not be handled (e.g. an enumerated string).  See
+	// NewFieldValueNotSupported.
 	ErrorTypeNotSupported ErrorType = "FieldValueNotSupported"
 	// ErrorTypeForbidden is used to report valid (as per formatting rules)
-	// values which would be accepted by some api instances, but which would invoke behavior
-	// not permitted by this api instance (such as due to stricter security policy).
+	// values which would be accepted under some conditions, but which are not
+	// permitted by the current conditions (such as security policy).  See
+	// NewFieldForbidden.
 	ErrorTypeForbidden ErrorType = "FieldValueForbidden"
-	// ErrorTypeTooLong is used to report that given value is too long.
+	// ErrorTypeTooLong is used to report that the given value is too long.
+	// This is similar to ErrorTypeInvalid, but the error will not include the
+	// too-long value.  See NewFieldTooLong.
 	ErrorTypeTooLong ErrorType = "FieldValueTooLong"
 )
 
-// String converts a ErrorType into its corresponding error message.
+// String converts a ErrorType into its corresponding canonical error message.
 func (t ErrorType) String() string {
 	switch t {
 	case ErrorTypeNotFound:
@@ -73,50 +110,39 @@ func (t ErrorType) String() string {
 	case ErrorTypeTooLong:
 		return "too long"
 	default:
-		panic(fmt.Sprintf("unrecognized validation type: %#v", t))
+		panic(fmt.Sprintf("unrecognized validation error: %q", t))
 		return ""
 	}
 }
 
-// Error is an implementation of the 'error' interface, which represents an error of validation.
-type Error struct {
-	Type     ErrorType
-	Field    string
-	BadValue interface{}
-	Detail   string
-}
-
-var _ error = &Error{}
-
-func (v *Error) Error() string {
-	return fmt.Sprintf("%s: %s", v.Field, v.ErrorBody())
-}
-
-func (v *Error) ErrorBody() string {
-	var s string
-	switch v.Type {
-	case ErrorTypeRequired, ErrorTypeTooLong:
-		s = spew.Sprintf("%s", v.Type)
-	default:
-		s = spew.Sprintf("%s '%+v'", v.Type, v.BadValue)
-	}
-	if len(v.Detail) != 0 {
-		s += fmt.Sprintf(", Details: %s", v.Detail)
-	}
-	return s
+// NewFieldNotFound returns a *Error indicating "value not found".  This is
+// used to report failure to find a requested value (e.g. looking up an ID).
+func NewFieldNotFound(field string, value interface{}) *Error {
+	return &Error{ErrorTypeNotFound, field, value, ""}
 }
 
-// NewFieldRequired returns a *Error indicating "value required"
+// NewFieldRequired returns a *Error indicating "value required".  This is used
+// to report required values that are not provided (e.g. empty strings, null
+// values, or empty arrays).
 func NewFieldRequired(field string) *Error {
 	return &Error{ErrorTypeRequired, field, "", ""}
 }
 
-// NewFieldInvalid returns a *Error indicating "invalid value"
+// NewFieldDuplicate returns a *Error indicating "duplicate value".  This is
+// used to report collisions of values that must be unique (e.g. names or IDs).
+func NewFieldDuplicate(field string, value interface{}) *Error {
+	return &Error{ErrorTypeDuplicate, field, value, ""}
+}
+
+// NewFieldInvalid returns a *Error indicating "invalid value".  This is used
+// to report malformed values (e.g. failed regex match, too long, out of bounds).
 func NewFieldInvalid(field string, value interface{}, detail string) *Error {
 	return &Error{ErrorTypeInvalid, field, value, detail}
 }
 
-// NewFieldValueNotSupported returns a *Error indicating "unsupported value"
+// NewFieldValueNotSupported returns a *Error indicating "unsupported value".
+// This is used to report valid (as per formatting rules) values that can not
+// be handled (e.g. an enumerated string).
 func NewFieldValueNotSupported(field string, value interface{}, validValues []string) *Error {
 	detail := ""
 	if validValues != nil && len(validValues) > 0 {
@@ -125,25 +151,23 @@ func NewFieldValueNotSupported(field string, value interface{}, validValues []st
 	return &Error{ErrorTypeNotSupported, field, value, detail}
 }
 
-// NewFieldForbidden returns a *Error indicating "forbidden"
+// NewFieldForbidden returns a *Error indicating "forbidden".  This is used to
+// report valid (as per formatting rules) values which would be accepted under
+// some conditions, but which are not permitted by current conditions (e.g.
+// security policy).
 func NewFieldForbidden(field string, value interface{}) *Error {
 	return &Error{ErrorTypeForbidden, field, value, ""}
 }
 
-// NewFieldDuplicate returns a *Error indicating "duplicate value"
-func NewFieldDuplicate(field string, value interface{}) *Error {
-	return &Error{ErrorTypeDuplicate, field, value, ""}
-}
-
-// NewFieldNotFound returns a *Error indicating "value not found"
-func NewFieldNotFound(field string, value interface{}) *Error {
-	return &Error{ErrorTypeNotFound, field, value, ""}
-}
-
+// NewFieldTooLong returns a *Error indicating "too long".  This is used to
+// report that the given value is too long.  This is similar to
+// NewFieldInvalid, but the returned error will not include the too-long
+// value.
 func NewFieldTooLong(field string, value interface{}, maxLength int) *Error {
 	return &Error{ErrorTypeTooLong, field, value, fmt.Sprintf("must have at most %d characters", maxLength)}
 }
 
+// ErrorList holds a set of errors.
 type ErrorList []error
 
 // Prefix adds a prefix to the Field of every Error in the list.