Firebase ML Kit Get Model API implementation (#326)

* added GetModel
* Added tests for get_model

Author: ifielker

.travis.yml

@@ -16,7 +16,6 @@ before_install:
   - nvm install 8 && npm install -g firebase-tools
 script:
   - pytest
-  - firebase emulators:exec --only database --project fake-project-id 'pytest integration/test_db.py'
 cache:
   pip: true
   npm: true

firebase_admin/mlkit.py

@@ -18,8 +18,77 @@
 deleting, publishing and unpublishing Firebase ML Kit models.
 """
 
+import re
+import requests
+import six
+
+from firebase_admin import _http_client
+from firebase_admin import _utils
+
+
+_MLKIT_ATTRIBUTE = '_mlkit'
+
+
+def _get_mlkit_service(app):
+    """ Returns an _MLKitService instance for an App.
+
+    Args:
+      app: A Firebase App instance (or None to use the default App).
+
+    Returns:
+      _MLKitService: An _MLKitService for the specified App instance.
+
+    Raises:
+      ValueError: If the app argument is invalid.
+    """
+    return _utils.get_app_service(app, _MLKIT_ATTRIBUTE, _MLKitService)
+
+
+def get_model(model_id, app=None):
+    mlkit_service = _get_mlkit_service(app)
+    return Model(mlkit_service.get_model(model_id))
+
+
+class Model(object):
+    """A Firebase ML Kit Model object."""
+    def __init__(self, data):
+        """Created from a data dictionary."""
+        self._data = data
+
+    def __eq__(self, other):
+        if isinstance(other, self.__class__):
+            return self._data == other._data # pylint: disable=protected-access
+        else:
+            return False
+
+    def __ne__(self, other):
+        return not self.__eq__(other)
+
+    #TODO(ifielker): define the Model properties etc
+
+
 class _MLKitService(object):
     """Firebase MLKit service."""
 
-    BASE_URL = 'https://mlkit.googleapis.com'
-    PROJECT_URL = 'https://mlkit.googleapis.com/projects/{0}/'
+    PROJECT_URL = 'https://mlkit.googleapis.com/v1beta1/projects/{0}/'
+
+    def __init__(self, app):
+        project_id = app.project_id
+        if not project_id:
+            raise ValueError(
+                'Project ID is required to access MLKit service. Either set the '
+                'projectId option, or use service account credentials.')
+        self._project_url = _MLKitService.PROJECT_URL.format(project_id)
+        self._client = _http_client.JsonHttpClient(
+            credential=app.credential.get_credential(),
+            base_url=self._project_url)
+
+    def get_model(self, model_id):
+        if not isinstance(model_id, six.string_types):
+            raise TypeError('Model ID must be a string.')
+        if not re.match(r'^[A-Za-z0-9_-]{1,60}$', model_id):
+            raise ValueError('Model ID format is invalid.')
+        try:
+            return self._client.body('get', url='models/{0}'.format(model_id))
+        except requests.exceptions.RequestException as error:
+            raise _utils.handle_platform_error_from_requests(error)

tests/test_mlkit.py

@@ -0,0 +1,134 @@
+# Copyright 2019 Google Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Test cases for the firebase_admin.mlkit module."""
+
+import json
+import pytest
+
+import firebase_admin
+from firebase_admin import exceptions
+from firebase_admin import mlkit
+from tests import testutils
+
+BASE_URL = 'https://mlkit.googleapis.com/v1beta1/'
+
+PROJECT_ID = 'myProject1'
+MODEL_ID_1 = 'modelId1'
+MODEL_NAME_1 = 'projects/{0}/models/{1}'.format(PROJECT_ID, MODEL_ID_1)
+DISPLAY_NAME_1 = 'displayName1'
+MODEL_JSON_1 = {
+    'name': MODEL_NAME_1,
+    'displayName': DISPLAY_NAME_1
+}
+MODEL_1 = mlkit.Model(MODEL_JSON_1)
+_DEFAULT_RESPONSE = json.dumps(MODEL_JSON_1)
+
+ERROR_CODE = 404
+ERROR_MSG = 'The resource was not found'
+ERROR_STATUS = 'NOT_FOUND'
+ERROR_JSON = {
+    'error': {
+        'code': ERROR_CODE,
+        'message': ERROR_MSG,
+        'status': ERROR_STATUS
+    }
+}
+_ERROR_RESPONSE = json.dumps(ERROR_JSON)
+
+
+class TestGetModel(object):
+    """Tests mlkit.get_model."""
+    @classmethod
+    def setup_class(cls):
+        cred = testutils.MockCredential()
+        firebase_admin.initialize_app(cred, {'projectId': PROJECT_ID})
+
+    @classmethod
+    def teardown_class(cls):
+        testutils.cleanup_apps()
+
+    @staticmethod
+    def check_error(err, err_type, msg):
+        assert isinstance(err, err_type)
+        assert str(err) == msg
+
+    @staticmethod
+    def check_firebase_error(err, code, status, msg):
+        assert isinstance(err, exceptions.FirebaseError)
+        assert err.code == code
+        assert err.http_response is not None
+        assert err.http_response.status_code == status
+        assert str(err) == msg
+
+    def _get_url(self, project_id, model_id):
+        return BASE_URL + 'projects/{0}/models/{1}'.format(project_id, model_id)
+
+    def _instrument_mlkit_service(self, app=None, status=200, payload=_DEFAULT_RESPONSE):
+        if not app:
+            app = firebase_admin.get_app()
+        mlkit_service = mlkit._get_mlkit_service(app)
+        recorder = []
+        mlkit_service._client.session.mount(
+            'https://mlkit.googleapis.com',
+            testutils.MockAdapter(payload, status, recorder)
+        )
+        return mlkit_service, recorder
+
+    def test_get_model(self):
+        _, recorder = self._instrument_mlkit_service()
+        model = mlkit.get_model(MODEL_ID_1)
+        assert len(recorder) == 1
+        assert recorder[0].method == 'GET'
+        assert recorder[0].url == self._get_url(PROJECT_ID, MODEL_ID_1)
+        assert model == MODEL_1
+        assert model._data['name'] == MODEL_NAME_1
+        assert model._data['displayName'] == DISPLAY_NAME_1
+
+    def test_get_model_validation_errors(self):
+        #Empty model-id
+        with pytest.raises(ValueError) as err:
+            mlkit.get_model('')
+        self.check_error(err.value, ValueError, 'Model ID format is invalid.')
+
+        #None model-id
+        with pytest.raises(TypeError) as err:
+            mlkit.get_model(None)
+        self.check_error(err.value, TypeError, 'Model ID must be a string.')
+
+        #Wrong type
+        with pytest.raises(TypeError) as err:
+            mlkit.get_model(12345)
+        self.check_error(err.value, TypeError, 'Model ID must be a string.')
+
+        #Invalid characters
+        with pytest.raises(ValueError) as err:
+            mlkit.get_model('&_*#@:/?')
+        self.check_error(err.value, ValueError, 'Model ID format is invalid.')
+
+    def test_get_model_error(self):
+        _, recorder = self._instrument_mlkit_service(status=404, payload=_ERROR_RESPONSE)
+        with pytest.raises(exceptions.NotFoundError) as err:
+            mlkit.get_model(MODEL_ID_1)
+        self.check_firebase_error(err.value, ERROR_STATUS, ERROR_CODE, ERROR_MSG)
+        assert len(recorder) == 1
+        assert recorder[0].method == 'GET'
+        assert recorder[0].url == self._get_url(PROJECT_ID, MODEL_ID_1)
+
+    def test_no_project_id(self):
+        def evaluate():
+            app = firebase_admin.initialize_app(testutils.MockCredential(), name='no_project_id')
+            with pytest.raises(ValueError):
+                mlkit.get_model(MODEL_ID_1, app)
+        testutils.run_without_project_id(evaluate)