Merge pull request #2 from matsuri-tech/feat/issue-1

feat: hidden tag

Author: 2222-42

README.md

@@ -1 +1,12 @@
 # json-hidden-marshal
+
+## Example
+
+```go
+type User struct {
+    Name     string `json:"name"`
+    Password string `json:"password" hidden:"mask"` // -> masked like "*****", preserving the string length 
+    Hidden   int    `json:"hidden" hidden:"-"`
+    Hidden2  int    `json:"hidden" hidden:"true"` // hidden:"-" or hidden:"true" to skip
+}
+```

go.mod

@@ -1,3 +1,5 @@
 module github.com/matsuri-tech/json-hidden-marshal
 
 go 1.15
+
+require github.com/stretchr/testify v1.7.0

go.sum

@@ -0,0 +1,11 @@
+github.com/davecgh/go-spew v1.1.0 h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8=
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.7.0 h1:nwc3DEeHmmLAfoZucVR881uASk0Mfjw8xYJ99tb5CcY=
+github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c h1:dUUwHk2QECo/6vqA44rthZ8ie2QXMNeKRTHCNY2nXvo=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

marshal.go

@@ -0,0 +1,70 @@
+package json_hidden_marshal
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"reflect"
+	"strings"
+)
+
+func scanToMap(val interface{}) (map[string]interface{}, error) {
+	strct := reflect.TypeOf(val)
+	values := reflect.ValueOf(val)
+
+	// pointerであればderefする
+	// 一度しかderefしないのよくわからなくない？という気持ちもあるけど…
+	if values.Kind() == reflect.Ptr {
+		strct = strct.Elem()
+		values = values.Elem()
+	}
+
+	m := map[string]interface{}{}
+	for i := 0; i < strct.NumField(); i++ {
+		field := strct.Field(i)
+		hidden := field.Tag.Get("hidden")
+
+		// Marshal時にmap[string]interface{}に置き換えるため、失われるjsonタグの対応をする必要がある
+		// 現状は名前の変更のみ対応
+		jsonTags := strings.Split(field.Tag.Get("json"), ",")
+		fieldName := field.Name
+		if len(jsonTags) >= 1 {
+			if jsonTags[0] != "" {
+				fieldName = jsonTags[0]
+			}
+		}
+
+		if hidden == "" {
+			ival := values.Field(i)
+			if ival.Kind() == reflect.Struct {
+				// PERF: 再帰をやめる
+				v, err := scanToMap(ival.Interface())
+				if err != nil {
+					return nil, err
+				}
+
+				m[fieldName] = v
+			} else {
+				// 構造体でないときはbase typeなのでそのまま
+				m[fieldName] = ival.Interface()
+			}
+		} else if hidden == "-" || hidden == "true" {
+			continue
+		} else if hidden == "mask" {
+			m[fieldName] = strings.Repeat("*", len(values.Field(i).String()))
+		} else {
+			return nil, errors.New(fmt.Sprintf("unsupported hidden tag: %v", hidden))
+		}
+	}
+
+	return m, nil
+}
+
+func Marshal(val interface{}) ([]byte, error) {
+	m, err := scanToMap(val)
+	if err != nil {
+		return nil, err
+	}
+
+	return json.Marshal(m)
+}

marshal_test.go

@@ -0,0 +1,76 @@
+package json_hidden_marshal
+
+import (
+	"github.com/stretchr/testify/assert"
+	"testing"
+)
+
+func TestMarshal(t *testing.T) {
+	cases := []struct {
+		in       interface{}
+		expected string
+	}{
+		{
+			// hidden:- or hidden:true to skip, hidden:mask to mask
+			in: struct {
+				Name     string `json:"name"`
+				Name2    string `json:"name2" hidden:"-"`       // skip
+				Name3    string `json:"name3" hidden:"true"`    // skip
+				Password string `json:"password" hidden:"mask"` // masked
+			}{
+				Name:     "foo",
+				Password: "password",
+			},
+			expected: `{"name":"foo","password":"********"}`,
+		},
+		{
+			// nested type
+			in: struct {
+				Nested struct {
+					Open   string `json:"open"`
+					Hidden string `json:"hidden" hidden:"-"`
+				} `json:"nested"`
+			}{
+				Nested: struct {
+					Open   string `json:"open"`
+					Hidden string `json:"hidden" hidden:"-"`
+				}{
+					Open:   "open",
+					Hidden: "hidden",
+				},
+			},
+			expected: `{"nested":{"open":"open"}}`,
+		},
+		{
+			// Without json tags
+			in: struct {
+				Name     string
+				Password string `hidden:"-"`
+			}{
+				Name:     "foo",
+				Password: "password",
+			},
+			expected: `{"Name":"foo"}`,
+		},
+		{
+			// Pass pointer
+			in: &struct {
+				Name     string `json:"name"`
+				Password string `json:"password" hidden:"mask"`
+			}{
+				Name:     "foo",
+				Password: "password",
+			},
+			expected: `{"name":"foo","password":"********"}`,
+		},
+	}
+
+	for _, c := range cases {
+		out, err := Marshal(c.in)
+		if err != nil {
+			t.Errorf("%+v\n", err)
+		}
+
+		assert.JSONEq(t, string(out), c.expected)
+	}
+}