From 1ae8ea0f03cfb9f25b1e25f3194c456c3649789c Mon Sep 17 00:00:00 2001
From: Simon Willison <simonw@eventbrite.com>
Date: Tue, 24 Oct 2017 17:06:23 -0700
Subject: [PATCH] Started implementing ?name__contains=X filters

So far we support __contains=, __startswith=, __endswith= and __exact=

Refs #23
---
 app.py          | 41 ++++++++++++++++++++++++++++++++++++++++-
 test_helpers.py | 19 +++++++++++++++++++
 2 files changed, 59 insertions(+), 1 deletion(-)

diff --git a/app.py b/app.py
index dc0711c1..0eb2dd98 100644
--- a/app.py
+++ b/app.py
@@ -183,7 +183,15 @@ class TableView(BaseView):
 
     def data(self, request, name, hash, table):
         conn = get_conn(name)
-        rows = conn.execute('select * from {} limit 20'.format(table))
+        if request.args:
+            where_clause, params = build_where_clause(request.args)
+            sql = 'select * from "{}" where {} limit 50'.format(
+                table, where_clause
+            )
+        else:
+            sql = 'select * from "{}" limit 50'.format(table)
+            params = []
+        rows = conn.execute(sql, params)
         columns = [r[0] for r in rows.description]
         pks = pks_for_table(conn, table)
         rows = list(rows)
@@ -294,6 +302,37 @@ def path_from_row_pks(row, pks):
     return ','.join(bits)
 
 
+def build_where_clause(args):
+    sql_bits = []
+    for key, values in args.items():
+        if '__' in key:
+            column, lookup = key.rsplit('__', 1)
+        else:
+            column = key
+            lookup = 'exact'
+        template = {
+            'exact': '"{}" = ?',
+            'contains': '"{}" like ?',
+            'endswith': '"{}" like ?',
+            'startswith': '"{}" like ?',
+        }[lookup]
+        value = values[0]
+        value_convert = {
+            'exact': lambda s: s,
+            'contains': lambda s: '%{}%'.format(s),
+            'endswith': lambda s: '%{}'.format(s),
+            'startswith': lambda s: '{}%'.format(s),
+        }[lookup]
+        converted = value_convert(value)
+        sql_bits.append(
+            (template.format(column), converted)
+        )
+    sql_bits.sort(key=lambda p: p[0])
+    where_clause = ' and '.join(p[0] for p in sql_bits)
+    params = [p[1] for p in sql_bits]
+    return where_clause, params
+
+
 class CustomJSONEncoder(json.JSONEncoder):
     def default(self, obj):
         if isinstance(obj, sqlite3.Row):
diff --git a/test_helpers.py b/test_helpers.py
index 42e90166..75779d71 100644
--- a/test_helpers.py
+++ b/test_helpers.py
@@ -64,3 +64,22 @@ def test_custom_json_encoder(obj, expected):
         sort_keys=True
     )
     assert expected == actual
+
+
+@pytest.mark.parametrize('args,expected_where,expected_params', [
+    ({
+        'name_english__contains': ['foo'],
+    }, '"name_english" like ?', ['%foo%']),
+    ({
+        'foo': ['bar'],
+        'bar__contains': ['baz'],
+    }, '"bar" like ? and "foo" = ?', ['%baz%', 'bar']),
+    ({
+        'foo__startswith': ['bar'],
+        'bar__endswith': ['baz'],
+    }, '"bar" like ? and "foo" like ?', ['%baz', 'bar%']),
+])
+def test_build_where(args, expected_where, expected_params):
+    actual_where, actual_params = app.build_where_clause(args)
+    assert expected_where == actual_where
+    assert expected_params == actual_params