From 09ac77d979d455dccba6bb73fad73b0b0cd8de85 Mon Sep 17 00:00:00 2001
From: sawandas <38201746+sawandas@users.noreply.github.com>
Date: Mon, 9 Apr 2018 12:10:44 +0530
Subject: [PATCH 1/2] Issue #1539 : Fixing dynamodb filtering (contains, begins
 with)

Currently contains and begins with are not respecting the given filter value
---
 moto/dynamodb2/comparisons.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/moto/dynamodb2/comparisons.py b/moto/dynamodb2/comparisons.py
index 68051460e..51d62fb83 100644
--- a/moto/dynamodb2/comparisons.py
+++ b/moto/dynamodb2/comparisons.py
@@ -176,6 +176,8 @@ def get_filter_expression(expr, names, values):
 
             next_token = six.next(token_iterator)
             while next_token != ')':
+                if next_token in values_map:
+                    next_token = values_map[next_token]
                 function_list.append(next_token)
                 next_token = six.next(token_iterator)
 

From 861c47a552db20c9f022856c66d7c2e82e506d42 Mon Sep 17 00:00:00 2001
From: sawandas <38201746+sawandas@users.noreply.github.com>
Date: Mon, 9 Apr 2018 13:42:50 +0530
Subject: [PATCH 2/2] Update test cases for dynamodb contains filter

---
 tests/test_dynamodb2/test_dynamodb.py | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/tests/test_dynamodb2/test_dynamodb.py b/tests/test_dynamodb2/test_dynamodb.py
index d7c5b5843..1d7fa4034 100644
--- a/tests/test_dynamodb2/test_dynamodb.py
+++ b/tests/test_dynamodb2/test_dynamodb.py
@@ -658,6 +658,14 @@ def test_filter_expression():
         {':v0': {'N': '7'}}
     )
     filter_expr.expr(row1).should.be(True)
+    # Expression from to check contains on string value
+    filter_expr = moto.dynamodb2.comparisons.get_filter_expression(
+        'contains(#n0, :v0)',
+        {'#n0': 'Desc'},
+        {':v0': {'S': 'Some'}}
+    )
+    filter_expr.expr(row1).should.be(True)
+    filter_expr.expr(row2).should.be(False)
 
 
 @mock_dynamodb2
@@ -699,6 +707,11 @@ def test_query_filter():
     )
     assert response['Count'] == 1
     assert response['Items'][0]['app'] == 'app2'
+    response = table.query(
+        KeyConditionExpression=Key('client').eq('client1'),
+        FilterExpression=Attr('app').contains('app')
+    )
+    assert response['Count'] == 2
 
 
 @mock_dynamodb2