Fix returning an empty flowable. Fixes #82

micronaut-projects · Oct 12, 2020 · 8e72f2b · 8e72f2b
1 parent 76b95e1
commit 8e72f2b
Show file tree

Hide file tree

Showing 2 changed files with 24 additions and 1 deletion.
diff --git a/http-server-jetty/src/test/groovy/io/micronaut/servlet/jetty/JettyJsonStreamSpec.groovy b/http-server-jetty/src/test/groovy/io/micronaut/servlet/jetty/JettyJsonStreamSpec.groovy
@@ -182,13 +182,25 @@ class JettyJsonStreamSpec extends Specification {
         result.timeout(10, TimeUnit.SECONDS).blockingGet().bookCount == 7
     }
 
+    void "test returning an empty publisher"() {
+        when:
+        List<Book> books = Flowable.fromPublisher(bookClient.empty()).toList().blockingGet()
+
+        then:
+        noExceptionThrown()
+        books.isEmpty()
+    }
+
     @Client("/jsonstream/books")
     static interface BookClient {
         @Get(consumes = MediaType.APPLICATION_JSON_STREAM)
         Publisher<Book> list();
 
         @Post(uri = "/count", processes = MediaType.APPLICATION_JSON_STREAM)
         Single<LibraryStats> count(@Body Flowable<Book> theBooks)
+
+        @Get(uri = "/empty", consumes = MediaType.APPLICATION_JSON)
+        Publisher<Book> empty();
     }
 
     @Controller("/jsonstream/books")
@@ -219,6 +231,11 @@ class JettyJsonStreamSpec extends Specification {
                     .map({ chunkList -> "\n" + chunkList.join("\n")})
                     .blockingGet()
         }
+
+        @Get(uri = "/empty", produces = MediaType.APPLICATION_JSON)
+        Publisher<Book> empty() {
+            return Flowable.empty()
+        }
     }
 
     static class Book {

diff --git a/servlet-engine/src/main/java/io/micronaut/servlet/engine/DefaultServletHttpResponse.java b/servlet-engine/src/main/java/io/micronaut/servlet/engine/DefaultServletHttpResponse.java
@@ -55,6 +55,8 @@
 @Internal
 public class DefaultServletHttpResponse<B> implements ServletHttpResponse<HttpServletResponse, B> {
 
+    private static final byte[] EMPTY_ARRAY = "[]".getBytes();
+
     private final HttpServletResponse delegate;
     private final DefaultServletHttpRequest<?> request;
     private final ServletResponseHeaders headers;
@@ -181,7 +183,11 @@ public void onComplete() {
                 if (finished.compareAndSet(false, true)) {
                     try {
                         if (!raw && isJson && outputStream.isReady()) {
-                            outputStream.write(']');
+                            if (first) { //empty publisher
+                                outputStream.write(EMPTY_ARRAY);
+                            } else {
+                                outputStream.write(']');
+                            }
                             flushIfReady();
                         }
                         emitter.onNext(DefaultServletHttpResponse.this);