fix(json): do not HTML-escape <, > and & in JSON output

CHANGELOG.md

@@ -17,6 +17,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Fixed
 
+- The JSON writer no longer escapes `<`, `>` and `&` as `\u003c`, `\u003e` and `\u0026`. That escaping is only needed when embedding JSON in HTML, so e.g. `dasel -i toml -o json` now emits `"setuptools>=77.0.3"` rather than `"setuptools\u003e=77.0.3"` ([#552](https://github.com/TomWright/dasel/issues/552)).
 - The TOML writer no longer relies on go-toml encoding a bare value as a document root, which go-toml v2.4 rejects. Selecting a scalar or list and writing it as TOML (e.g. `dasel -i json -o toml 'hello'`) works again.
 - Writing a list of tables as the top level value now emits a valid inline array of tables (e.g. `[{a = 1}, {a = 2}]`) instead of table headers with an empty key.
 

parsing/json/json_test.go

@@ -96,6 +96,35 @@ func TestJsonCompact(t *testing.T) {
 	}
 }
 
+func TestJsonDoesNotEscapeHTMLCharacters(t *testing.T) {
+	doc := []byte(`{
+    "string": "setuptools>=77.0.3 & <b>"
+}
+`)
+	reader, err := json.JSON.NewReader(parsing.DefaultReaderOptions())
+	if err != nil {
+		t.Fatal(err)
+	}
+	writer, err := json.JSON.NewWriter(parsing.DefaultWriterOptions())
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	value, err := reader.Read(doc)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	newDoc, err := writer.Write(value)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if string(doc) != string(newDoc) {
+		t.Fatalf("expected %s, got %s...\n%s", string(doc), string(newDoc), cmp.Diff(string(doc), string(newDoc)))
+	}
+}
+
 func TestNDJSON(t *testing.T) {
 	newReader := func(t *testing.T) parsing.Reader {
 		t.Helper()

parsing/json/json_writer.go

@@ -34,11 +34,17 @@ func (j *jsonWriter) Write(value *model.Value) ([]byte, error) {
 	}
 
 	encoderFn := func(v any) error {
-		res, err := json.Marshal(v)
-		if err != nil {
+		// json.Marshal escapes <, > and & as \u003c, \u003e and \u0026.
+		// That is only required when embedding JSON in HTML, so use an
+		// encoder with HTML escaping disabled to keep the output readable.
+		valBuf := new(bytes.Buffer)
+		enc := json.NewEncoder(valBuf)
+		enc.SetEscapeHTML(false)
+		if err := enc.Encode(v); err != nil {
 			return err
 		}
-		_, err = buf.Write(res)
+		// Encode appends a trailing newline that we do not want here.
+		_, err := buf.Write(bytes.TrimSuffix(valBuf.Bytes(), []byte("\n")))
 		return err
 	}