From 4dec187d80a59cbe0d1a8b78d58dab20131516f7 Mon Sep 17 00:00:00 2001
From: Bert Blommers <info@bertblommers.nl>
Date: Sat, 5 Oct 2019 15:20:43 +0100
Subject: [PATCH] #1834 - Check item size in DynamoDB

---
 moto/dynamodb2/responses.py           |  4 ++++
 tests/test_dynamodb2/test_dynamodb.py | 21 +++++++++++++++++++++
 2 files changed, 25 insertions(+)

diff --git a/moto/dynamodb2/responses.py b/moto/dynamodb2/responses.py
index d07beefd6..e7f5f2825 100644
--- a/moto/dynamodb2/responses.py
+++ b/moto/dynamodb2/responses.py
@@ -225,6 +225,10 @@ class DynamoHandler(BaseResponse):
             er = 'com.amazonaws.dynamodb.v20111205#ValidationException'
             return self.error(er, 'Return values set to invalid value')
 
+        if len(str(item).encode('utf-8')) > 405000:
+            er = 'com.amazonaws.dynamodb.v20111205#ValidationException'
+            return self.error(er, 'Item size has exceeded the maximum allowed size')
+
         if has_empty_keys_or_values(item):
             return get_empty_str_error()
 
diff --git a/tests/test_dynamodb2/test_dynamodb.py b/tests/test_dynamodb2/test_dynamodb.py
index b0952f101..4fd0fb472 100644
--- a/tests/test_dynamodb2/test_dynamodb.py
+++ b/tests/test_dynamodb2/test_dynamodb.py
@@ -2278,6 +2278,27 @@ def test_index_with_unknown_attributes_should_fail():
     ex.exception.response['Error']['Message'].should.contain(expected_exception)
 
 
+# https://github.com/spulec/moto/issues/1874
+@mock_dynamodb2
+def test_item_size_is_under_400KB():
+    dynamodb = boto3.client('dynamodb', region_name='us-east-1')
+
+    dynamodb.create_table(
+        TableName='moto-test',
+        KeySchema=[{'AttributeName': 'id', 'KeyType': 'HASH'}],
+        AttributeDefinitions=[{'AttributeName': 'id', 'AttributeType': 'S'}],
+        ProvisionedThroughput={'ReadCapacityUnits': 1, 'WriteCapacityUnits': 1}
+    )
+
+    with assert_raises(ClientError) as ex:
+        large_item = 'x' * 410 * 1000
+        dynamodb.put_item(
+            TableName='moto-test',
+            Item={'id': {'S': 'foo'}, 'item': {'S': large_item}})
+    ex.exception.response['Error']['Code'].should.equal('ValidationException')
+    ex.exception.response['Error']['Message'].should.equal('Item size has exceeded the maximum allowed size')
+
+
 def _create_user_table():
     client = boto3.client('dynamodb', region_name='us-east-1')
     client.create_table(