From 6fd93368f1db2277d00bec9f2628224d652ceab1 Mon Sep 17 00:00:00 2001
From: Jim Ferenczi <jim.ferenczi@elastic.co>
Date: Fri, 18 May 2018 12:00:33 +0200
Subject: [PATCH] Ignore empty completion input

This change makes sure that an empty completion input does not throw an IAE when indexing.
Instead the input is ignored and the completion field is added in the list of ignored fields
for the document.

Closes #23121
---
 .../index/mapper/CompletionFieldMapper.java         |  4 ++++
 .../index/mapper/CompletionFieldMapperTests.java    | 13 +++++++++++++
 2 files changed, 17 insertions(+)

diff --git a/server/src/main/java/org/elasticsearch/index/mapper/CompletionFieldMapper.java b/server/src/main/java/org/elasticsearch/index/mapper/CompletionFieldMapper.java
index af50dfbcb4e18..cf08d93a197de 100644
--- a/server/src/main/java/org/elasticsearch/index/mapper/CompletionFieldMapper.java
+++ b/server/src/main/java/org/elasticsearch/index/mapper/CompletionFieldMapper.java
@@ -449,6 +449,10 @@ public Mapper parse(ParseContext context) throws IOException {
         // index
         for (Map.Entry<String, CompletionInputMetaData> completionInput : inputMap.entrySet()) {
             String input = completionInput.getKey();
+            if (input.trim().isEmpty()) {
+                context.addIgnoredField(fieldType.name());
+                continue;
+            }
             // truncate input
             if (input.length() > maxInputLength) {
                 int len = Math.min(maxInputLength, input.length());
diff --git a/server/src/test/java/org/elasticsearch/index/mapper/CompletionFieldMapperTests.java b/server/src/test/java/org/elasticsearch/index/mapper/CompletionFieldMapperTests.java
index be03a28a0aad2..1381b6e920559 100644
--- a/server/src/test/java/org/elasticsearch/index/mapper/CompletionFieldMapperTests.java
+++ b/server/src/test/java/org/elasticsearch/index/mapper/CompletionFieldMapperTests.java
@@ -397,6 +397,19 @@ public void testFieldValueValidation() throws Exception {
             assertThat(cause, instanceOf(IllegalArgumentException.class));
             assertThat(cause.getMessage(), containsString("[0x1e]"));
         }
+
+        // empty inputs are ignored
+        ParsedDocument doc = defaultMapper.parse(SourceToParse.source("test", "type1", "1", BytesReference
+                .bytes(XContentFactory.jsonBuilder()
+                    .startObject()
+                    .array("completion", "   ", "")
+                    .endObject()),
+            XContentType.JSON));
+        assertThat(doc.docs().size(), equalTo(1));
+        assertNull(doc.docs().get(0).get("completion"));
+        assertNotNull(doc.docs().get(0).getField("_ignored"));
+        IndexableField ignoredFields = doc.docs().get(0).getField("_ignored");
+        assertThat(ignoredFields.stringValue(), equalTo("completion"));
     }
 
     public void testPrefixQueryType() throws Exception {