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// Copyright 2019 Red Hat, Inc
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.)
package validate
import (
"reflect"
"strings"
"github.com/coreos/vcontext/path"
"github.com/coreos/vcontext/report"
)
type CustomValidator func(v reflect.Value, c path.ContextPath) report.Report
// validator is the interface the DefaultValidator function uses when validating types.
// Most users should implement this interface on types they want to validate.
type validator interface {
Validate(path.ContextPath) report.Report
}
// DefaultValidator checks if the type implements the validator interface and calls the
// validate function if it does, returning the report.
func DefaultValidator(v reflect.Value, c path.ContextPath) report.Report {
// first check if this object has Validate(context) defined, but only on value
// recievers. Both pointer and value receivers satisfy a value receiver interface
// so ensure we're not a pointer too.
if obj, ok := v.Interface().(validator); ok && v.Kind() != reflect.Ptr {
return obj.Validate(c)
}
return report.Report{}
}
// ValidateCustom validates thing using the custom validation function supplied. Most users will not need this
// and should use Validate() instead.
func ValidateCustom(thing interface{}, tag string, customValidator CustomValidator) report.Report {
if thing == nil {
return report.Report{}
}
v := reflect.ValueOf(thing)
ctx := path.ContextPath{Tag: tag}
return validate(ctx, v, customValidator)
}
// Validate walks the structs, slices, and pointers in thing and calls any Validate(path.ContextPath) report.Report
// functions defined on the types, aggregating the results.
func Validate(thing interface{}, tag string) report.Report {
return ValidateCustom(thing, tag, DefaultValidator)
}
func validate(context path.ContextPath, v reflect.Value, validateFunc CustomValidator) (r report.Report) {
if !v.IsValid() {
return
}
if v.Kind() == reflect.Interface {
if v.IsNil() {
return
} else {
v = makeConcrete(v)
}
}
r.Merge(validateFunc(v, context))
switch v.Kind() {
case reflect.Struct:
r.Merge(validateStruct(context, v, validateFunc))
case reflect.Slice:
r.Merge(validateSlice(context, v, validateFunc))
case reflect.Ptr:
if !v.IsNil() {
r.Merge(validate(context, v.Elem(), validateFunc))
}
}
return
}
// StructField is an extension of go's reflect.StructField that also includes the value.
type StructField struct {
reflect.StructField
Value reflect.Value
}
// makeConcrete takes a value and if it is a value of an interface returns the
// value of the actual underlying type implementing that interface. If the value
// is already concrete, it returns the same value.
func makeConcrete(v reflect.Value) reflect.Value {
return reflect.ValueOf(v.Interface())
}
// GetFields takes a value of a struct and flattens all embedded structs in it.
// If any fields are interfaces, it "dereferences" the interface to its underlying type.
func GetFields(v reflect.Value) []StructField {
ret := []StructField{}
if v.Kind() != reflect.Struct {
return ret
}
for i := 0; i < v.NumField(); i++ {
field := v.Type().Field(i)
if !field.Anonymous {
ret = append(ret, StructField{
StructField: field,
Value: v.Field(i),
})
} else {
concrete := makeConcrete(v.Field(i))
ret = append(ret, GetFields(concrete)...)
}
}
return ret
}
func FieldName(s StructField, tag string) string {
if tag == "" {
return s.Name
}
tag = s.Tag.Get(tag)
return strings.Split(tag, ",")[0]
}
func validateStruct(context path.ContextPath, v reflect.Value, f CustomValidator) (r report.Report) {
fields := GetFields(v)
for _, field := range fields {
fieldContext := context.Append(FieldName(field, context.Tag))
r.Merge(validate(fieldContext, field.Value, f))
}
return
}
func validateSlice(context path.ContextPath, v reflect.Value, f CustomValidator) (r report.Report) {
for i := 0; i < v.Len(); i++ {
childContext := context.Append(i)
r.Merge(validate(childContext, v.Index(i), f))
}
return
}
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