docs(user): add query strings tutorial

docs/user/tutorial.rst

@@ -1174,7 +1174,7 @@ Go ahead and edit your ``images.py`` file to look something like this:
 
         _CHUNK_SIZE_BYTES = 4096
         _IMAGE_NAME_PATTERN = re.compile(
-            '[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}\.[a-z]{2,4}$'
+            r'[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}\.[a-z]{2,4}$'
         )
 
         def __init__(self, storage_path, uuidgen=uuid.uuid4, fopen=io.open):
@@ -1307,7 +1307,7 @@ Inspecting the application now returns:
 Query Strings
 -------------
 Now that we are able to get the images from the service, we need a way to get
-a list available images. We have already set up this route. Before testing this
+a list of available images. We have already set up this route. Before testing this
 route let's change its output format back to JSON to have a more
 terminal-friendly output. The top of file ``images.py`` should look like this:
 
@@ -1390,7 +1390,7 @@ and also to enable a minimum value validation.
             self._image_store = image_store
 
         def on_get(self, req, resp):
-            max_size = req.get_param_as_int("maxsize", min_value=1, default=-1))
+            max_size = req.get_param_as_int("maxsize", min_value=1, default=-1)
             images = self._image_store.list(max_size)
             doc = {
                 'images': [
@@ -1421,7 +1421,7 @@ and also to enable a minimum value validation.
 
         _CHUNK_SIZE_BYTES = 4096
         _IMAGE_NAME_PATTERN = re.compile(
-            '[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}\.[a-z]{2,4}$'
+            r'[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}\.[a-z]{2,4}$'
         )
 
         def __init__(self, storage_path, uuidgen=uuid.uuid4, fopen=io.open):

examples/look/look/app.py

@@ -2,14 +2,15 @@
 
 import falcon
 
+from .images import Collection
 from .images import ImageStore
-from .images import Resource
+from .images import Item
 
 
 def create_app(image_store):
-    image_resource = Resource(image_store)
     app = falcon.App()
-    app.add_route('/images', image_resource)
+    app.add_route('/images', Collection(image_store))
+    app.add_route('/images/{name}', Item(image_store))
     return app
 
 

examples/look/look/images.py

@@ -1,28 +1,23 @@
 import io
+import json
 import mimetypes
 import os
+import re
 import uuid
 
-import msgpack
-
 import falcon
 
 
-class Resource:
+class Collection:
     def __init__(self, image_store):
         self._image_store = image_store
 
     def on_get(self, req, resp):
-        doc = {
-            'images': [
-                {
-                    'href': '/images/1eaf6ef1-7f2d-4ecc-a8d5-6e8adba7cc0e.png',
-                },
-            ],
-        }
-
-        resp.data = msgpack.packb(doc, use_bin_type=True)
-        resp.content_type = 'application/msgpack'
+        max_size = req.get_param_as_int('maxsize', min_value=1, default=-1)
+        images = self._image_store.list(max_size)
+        doc = {'images': [{'href': '/images/' + image} for image in images]}
+
+        resp.text = json.dumps(doc, ensure_ascii=False)
         resp.status = falcon.HTTP_200
 
     def on_post(self, req, resp):
@@ -31,8 +26,20 @@ def on_post(self, req, resp):
         resp.location = '/images/' + name
 
 
+class Item:
+    def __init__(self, image_store):
+        self._image_store = image_store
+
+    def on_get(self, req, resp, name):
+        resp.content_type = mimetypes.guess_type(name)[0]
+        resp.stream, resp.content_length = self._image_store.open(name)
+
+
 class ImageStore:
     _CHUNK_SIZE_BYTES = 4096
+    _IMAGE_NAME_PATTERN = re.compile(
+        r'[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}\.[a-z]{2,4}$'
+    )
 
     # Note the use of dependency injection for standard library
     # methods. We'll use these later to avoid monkey-patching.
@@ -55,3 +62,26 @@ def save(self, image_stream, image_content_type):
                 image_file.write(chunk)
 
         return name
+
+    def open(self, name):
+        # Always validate untrusted input!
+        if not self._IMAGE_NAME_PATTERN.match(name):
+            raise IOError('File not found')
+
+        image_path = os.path.join(self._storage_path, name)
+        stream = self._fopen(image_path, 'rb')
+        content_length = os.path.getsize(image_path)
+
+        return stream, content_length
+
+    def list(self, max_size):
+        images = [
+            image
+            for image in os.listdir(self._storage_path)
+            if self._IMAGE_NAME_PATTERN.match(image)
+            and (
+                max_size == -1
+                or os.path.getsize(os.path.join(self._storage_path, image)) <= max_size
+            )
+        ]
+        return images

examples/look/tests/test_app.py

@@ -1,10 +1,13 @@
 import io
+import json
+import os
+from unittest import TestCase
 from unittest.mock import call
 from unittest.mock import MagicMock
 from unittest.mock import mock_open
+import uuid
 from wsgiref.validate import InputWrapper
 
-import msgpack
 import pytest
 
 import falcon
@@ -25,19 +28,17 @@ def client(mock_store):
     return testing.TestClient(api)
 
 
-def test_list_images(client):
-    doc = {
-        'images': [
-            {
-                'href': '/images/1eaf6ef1-7f2d-4ecc-a8d5-6e8adba7cc0e.png',
-            },
-        ],
-    }
+def test_list_images(client, mock_store):
+    images = ['first-file', 'second-file', 'third-file']
+    image_docs = [{'href': '/images/' + image} for image in images]
+
+    mock_store.list.return_value = images
 
     response = client.simulate_get('/images')
-    result_doc = msgpack.unpackb(response.content, raw=False)
 
-    assert result_doc == doc
+    result = json.loads(response.content)
+
+    assert result['images'] == image_docs
     assert response.status == falcon.HTTP_OK
 
 
@@ -64,7 +65,7 @@ def test_post_image(client, mock_store):
     assert saver_call[0][1] == image_content_type
 
 
-def test_saving_image(monkeypatch):
+def test_saving_image():
     # This still has some mocks, but they are more localized and do not
     # have to be monkey-patched into standard library modules (always a
     # risky business).
@@ -84,3 +85,55 @@ def mock_uuidgen():
 
     assert store.save(fake_request_stream, 'image/png') == fake_uuid + '.png'
     assert call().write(fake_image_bytes) in mock_file_open.mock_calls
+
+
+def test_get_image(client, mock_store):
+    file_bytes = b'fake-image-bytes'
+
+    mock_store.open.return_value = ((file_bytes,), 17)
+
+    response = client.simulate_get('/images/filename.png')
+
+    assert response.status == falcon.HTTP_OK
+    assert response.content == file_bytes
+
+
+def test_opening_image():
+    file_name = f'{uuid.uuid4()}.png'
+    storage_path = '.'
+    file_path = f'{storage_path}/{file_name}'
+    fake_image_bytes = b'fake-image-bytes'
+    with open(file_path, 'wb') as image_file:
+        file_length = image_file.write(fake_image_bytes)
+
+    store = look.images.ImageStore(storage_path)
+
+    file_reader, content_length = store.open(file_name)
+    assert content_length == file_length
+    assert file_reader.read() == fake_image_bytes
+    os.remove(file_path)
+
+    with TestCase().assertRaises(IOError):
+        store.open('wrong_file_name_format')
+
+
+def test_listing_images():
+    file_names = [f'{uuid.uuid4()}.png' for _ in range(2)]
+    storage_path = '.'
+    file_paths = [f'{storage_path}/{name}' for name in file_names]
+    fake_images_bytes = [
+        b'fake-image-bytes',  # 17
+        b'fake-image-bytes-with-more-length',  # 34
+    ]
+    for i in range(2):
+        with open(file_paths[i], 'wb') as image_file:
+            image_file.write(fake_images_bytes[i])
+
+    store = look.images.ImageStore(storage_path)
+    assert store.list(10) == []
+    assert store.list(20) == [file_names[0]]
+    assert len(store.list(40)) == 2
+    assert sorted(store.list(40)) == sorted(file_names)
+
+    for file_path in file_paths:
+        os.remove(file_path)