From 741ff717ad4decc8d3a02ae2bb1d18dcef58abab Mon Sep 17 00:00:00 2001
From: Julien Le Dem <julien@dremio.com>
Date: Thu, 8 Dec 2016 21:56:09 -0800
Subject: [PATCH] ARROW-400: set struct length on json load

---
 .../main/java/org/apache/arrow/vector/complex/MapVector.java  | 2 +-
 .../org/apache/arrow/vector/file/json/JsonFileReader.java     | 4 ++++
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/java/vector/src/main/java/org/apache/arrow/vector/complex/MapVector.java b/java/vector/src/main/java/org/apache/arrow/vector/complex/MapVector.java
index c2f216b197e..31a1bb74b8e 100644
--- a/java/vector/src/main/java/org/apache/arrow/vector/complex/MapVector.java
+++ b/java/vector/src/main/java/org/apache/arrow/vector/complex/MapVector.java
@@ -50,7 +50,7 @@ public class MapVector extends AbstractMapVector {
   private final SingleMapReaderImpl reader = new SingleMapReaderImpl(this);
   private final Accessor accessor = new Accessor();
   private final Mutator mutator = new Mutator();
-  int valueCount;
+  public int valueCount;
 
   public MapVector(String name, BufferAllocator allocator, CallBack callBack) {
     super(name, allocator, callBack);
diff --git a/java/vector/src/main/java/org/apache/arrow/vector/file/json/JsonFileReader.java b/java/vector/src/main/java/org/apache/arrow/vector/file/json/JsonFileReader.java
index 26dd3f6dfe5..152867c1a11 100644
--- a/java/vector/src/main/java/org/apache/arrow/vector/file/json/JsonFileReader.java
+++ b/java/vector/src/main/java/org/apache/arrow/vector/file/json/JsonFileReader.java
@@ -47,6 +47,7 @@
 import org.apache.arrow.vector.ValueVector.Mutator;
 import org.apache.arrow.vector.VarCharVector;
 import org.apache.arrow.vector.VectorSchemaRoot;
+import org.apache.arrow.vector.complex.NullableMapVector;
 import org.apache.arrow.vector.schema.ArrowVectorType;
 import org.apache.arrow.vector.types.pojo.Field;
 import org.apache.arrow.vector.types.pojo.Schema;
@@ -153,6 +154,9 @@ private void readVector(Field field, FieldVector vector) throws JsonParseExcepti
         }
         readToken(END_ARRAY);
       }
+      if (vector instanceof NullableMapVector) {
+        ((NullableMapVector)vector).valueCount = count;
+      }
     }
     readToken(END_OBJECT);
   }