Merge pull request #230 from invopop/c14n-marshal

Support c14n direct marshalling

c14n/README.md

@@ -12,9 +12,9 @@ One of the objectives of GoBL is to create a document that could potentially be
 
 This `c14n` package, inspired by the works of others, thus aims to define a simple standardized approach to canonical JSON that could potentially be implemented easily in other languages. More than just a definition, the code here is a reference implementation from which libraries can be made in languages other than Go.
 
-## GoBL JSON C14n
+## GOBL JSON C14n
 
-GoBL considers the following JSON values as explicit types:
+GOBL considers the following JSON values as explicit types:
 
 - a string
 - a number, which extends the JSON spec and is split into:
@@ -56,7 +56,7 @@ JSON in canonical form:
    2. using six-character `\u00XX` uppercase hexadecimal escape sequences for control characters that require escaping but lack a two-character sequence described previously, and
    3. reject any string containing invalid encoding.
 
-The GoBL JSON c14n package has been designed to operate using any raw JSON source and uses the Go [`encoding/json`](https://golang.org/pkg/encoding/json/) library's streaming methods to parse and recreate a document in memory. A simplified object model is used to map JSON structures ready to be converted into canonical JSON.
+The GOBL JSON c14n package has been designed to operate using any raw JSON source and uses the Go [`encoding/json`](https://golang.org/pkg/encoding/json/) library's streaming methods to parse and recreate a document in memory. A simplified object model is used to map JSON structures ready to be converted into canonical JSON.
 
 ## Usage Example
 

c14n/c14n.go

@@ -2,8 +2,10 @@
 package c14n
 
 import (
+	"bytes"
 	"encoding/json"
 	"errors"
+	"fmt"
 	"io"
 )
 
@@ -23,6 +25,17 @@ func UnmarshalJSON(src io.Reader) (Canonicalable, error) {
 	return res, nil
 }
 
+// MarshalJSON takes any Go object that can be serialized into JSON and generates
+// the canonical JSON representation of that object.
+func MarshalJSON(src any) ([]byte, error) {
+	data := new(bytes.Buffer)
+	enc := json.NewEncoder(data)
+	if err := enc.Encode(src); err != nil {
+		return nil, fmt.Errorf("encoding: %w", err)
+	}
+	return CanonicalJSON(data)
+}
+
 // CanonicalJSON performs the unmarshal and marshal commands in one go.
 func CanonicalJSON(src io.Reader) ([]byte, error) {
 	obj, err := UnmarshalJSON(src)

c14n/c14n_test.go

@@ -7,6 +7,7 @@ import (
 	"testing"
 
 	"github.com/invopop/gobl/c14n"
+	"github.com/stretchr/testify/assert"
 )
 
 func TestJSONToArray(t *testing.T) {
@@ -69,3 +70,19 @@ func TestJSONToArray(t *testing.T) {
 		t.Errorf("unexpected sum, please check marshaled data, got: %v", s)
 	}
 }
+
+func TestMarshalJSON(t *testing.T) {
+	obj := struct {
+		Title string `json:"title"`
+		Idx   int64  `json:"idx"`
+		Body  string `json:"body,omitempty"`
+	}{
+		Title: "test",
+		Idx:   1,
+		Body:  "Test body to play around with",
+	}
+	d, err := c14n.MarshalJSON(obj)
+	assert.NoError(t, err)
+	out := `{"body":"Test body to play around with","idx":1,"title":"test"}`
+	assert.Contains(t, string(d), out)
+}

version.go

@@ -8,7 +8,7 @@ import (
 type Version string
 
 // VERSION is the current version of the GOBL library.
-const VERSION Version = "v0.65.1"
+const VERSION Version = "v0.65.2"
 
 // Semver parses and returns semver
 func (v Version) Semver() *semver.Version {