Merge pull request #15130 from codeconsole/7.0.x-gson-datecal-precision

gson views date/calendar should have millisecond precision to match standard rendering

Author: codeconsole

grails-views-gson/src/main/groovy/grails/plugin/json/builder/JsonGenerator.java

@@ -121,7 +121,7 @@ interface Converter {
      */
     class Options {
 
-        protected static final String JSON_DATE_FORMAT = "yyyy-MM-dd'T'HH:mm:ssZ";
+        protected static final String JSON_DATE_FORMAT = "yyyy-MM-dd'T'HH:mm:ss.SSSX";
         protected static final Locale JSON_DATE_FORMAT_LOCALE = Locale.US;
         protected static final String DEFAULT_TIMEZONE = "GMT";
 

grails-views-gson/src/main/groovy/grails/plugin/json/view/JsonViewGeneratorConfiguration.groovy

@@ -29,7 +29,7 @@ class JsonViewGeneratorConfiguration {
 
     Boolean escapeUnicode = false
 
-    String dateFormat = /yyyy-MM-dd'T'HH:mm:ss'Z'/
+    String dateFormat = /yyyy-MM-dd'T'HH:mm:ss.SSSX/
 
     String timeZone = 'GMT'
 

grails-views-gson/src/test/groovy/grails/plugin/json/view/DateTimeRenderingSpec.groovy

@@ -62,8 +62,8 @@ json {
             createdInstant: instant
         ])
 
-        then: "Date and Instant render with Z suffix"
-        result.json.createdDate == "2025-10-07T21:14:31Z"
+        then: "Date and Instant render with Z suffix and millisecond precision"
+        result.json.createdDate == "2025-10-07T21:14:31.000Z"
         result.json.createdInstant == "2025-10-07T21:14:31Z"
 
         and: "LocalDateTime renders without timezone (local time)"
@@ -194,4 +194,37 @@ json {
         result.json.date == "2025-10-08"
         result.json.date instanceof String
     }
+
+    void "Test Date and Calendar render with millisecond precision"() {
+        given: "A view that renders Date and Calendar"
+        String source = '''
+model {
+    Date date
+    Calendar calendar
+}
+
+json {
+    date date
+    calendar calendar
+}
+'''
+
+        and: "Date and Calendar with millisecond precision"
+        // Create a date with 407 milliseconds: 2025-10-08T07:48:46.407Z
+        def calendar = Calendar.getInstance(TimeZone.getTimeZone("GMT"))
+        calendar.set(2025, Calendar.OCTOBER, 8, 7, 48, 46)
+        calendar.set(Calendar.MILLISECOND, 407)
+        def date = calendar.getTime()
+
+        when: "The view is rendered"
+        def result = render(source, [date: date, calendar: calendar])
+
+        then: "Date renders with millisecond precision"
+        result.json.date == "2025-10-08T07:48:46.407Z"
+        result.json.date instanceof String
+
+        and: "Calendar renders with millisecond precision"
+        result.json.calendar == "2025-10-08T07:48:46.407Z"
+        result.json.calendar instanceof String
+    }
 }