Build a Cloud Aspect Engine whose product the key lacks, and log it once

location/src/fiftyone_location/location_cloud.py

@@ -44,12 +44,3 @@ def __init__(self, location_provider="fiftyonedegrees"):
             self.datakey = "location_digitalelement"
         else:
             raise Exception("The location provider " + location_provider + " was not recognized.")
-
-    def on_registration(self, pipeline):
-        available_properties = pipeline.flow_elements_list.get(
-            "cloud", {}).flow_element_properties
-        if "location" not in available_properties:
-            raise Exception("Location data was not available. "
-                            "Check that this key is authorised "
-                            "for geolocation data")
-        return super().on_registration(pipeline)

pipeline/fiftyone_pipeline_cloudrequestengine/src/fiftyone_pipeline_cloudrequestengine/cloudengine.py

@@ -82,11 +82,15 @@ def on_registration(self, pipeline):
 
         # The accessible properties come from the cloud service for the
         # key in use, a resource key or a licence key, so a section missing
-        # from them means that key does not carry the product at all.
-        if not self.datakey in pipeline.flow_elements_list["cloud"].flow_element_properties:
-            raise Exception("The key in use does not include access to any properties under the engine with key " + self.datakey +  " that was added to the pipeline. For more details on resource keys, see our explainer: https://51degrees.com/documentation/_services__cloud__resource_keys.html?utm_source=code&utm_medium=comment&utm_campaign=51degrees-python&utm_content=fiftyone_pipeline_cloudrequestengine-src-fiftyone_pipeline_cloudrequestengine-cloudengine.py&utm_term=engine-properties-not-accessible " + "Available engine data keys are: " + str([e for e in pipeline.flow_elements_list["cloud"].flow_element_properties]))
-
-        self.properties = pipeline.flow_elements_list["cloud"].flow_element_properties[self.datakey]
+        # from them means that key does not carry the product at all. That
+        # is not a configuration error, so the engine is built with no
+        # properties and the missing product is logged here, once.
+        carried = pipeline.flow_elements_list["cloud"].flow_element_properties
+        if not self.datakey in carried:
+            pipeline.log("warning", "The key in use does not include access to any properties under the engine with key " + self.datakey +  " that was added to the pipeline. For more details on resource keys, see our explainer: https://51degrees.com/documentation/_services__cloud__resource_keys.html?utm_source=code&utm_medium=comment&utm_campaign=51degrees-python&utm_content=fiftyone_pipeline_cloudrequestengine-src-fiftyone_pipeline_cloudrequestengine-cloudengine.py&utm_term=engine-properties-not-accessible " + "Available engine data keys are: " + str([e for e in carried]))
+            self.properties = {}
+        else:
+            self.properties = carried[self.datakey]
 
         # Add a special message to the pipeline 
         # when requesting an element that does not exist

pipeline/fiftyone_pipeline_cloudrequestengine/tests/test_cloudengine_missing_product.py

@@ -0,0 +1,97 @@
+
+"""
+A Cloud Aspect Engine whose product the key does not include builds with
+empty Property metadata, logs the missing product once, and logs nothing
+about it on each response, as the Cloud Aspect Engine specification says.
+"""
+
+import json
+import unittest
+
+from fiftyone_pipeline_cloudrequestengine.cloudengine import CloudEngine
+from fiftyone_pipeline_core.elementdata_dictionary import ElementDataDictionary
+from fiftyone_pipeline_core.flowelement import FlowElement
+from fiftyone_pipeline_core.logger import Logger
+from fiftyone_pipeline_core.pipelinebuilder import PipelineBuilder
+
+
+class RecordingLogger(Logger):
+
+    def __init__(self):
+        super(RecordingLogger, self).__init__("debug")
+        self.logged = []
+
+    def log_internal(self, level, log):
+        self.logged.append((level, log["message"]))
+
+
+class FakeCloudRequestEngine(FlowElement):
+    """Stands in for the Cloud Request Engine of a key that carries only the
+    device product."""
+
+    def __init__(self):
+        super(FakeCloudRequestEngine, self).__init__()
+        self.datakey = "cloud"
+        self.flow_element_properties = {
+            "device": {"ismobile": {"name": "IsMobile", "type": "Boolean"}}}
+
+    def process_internal(self, flowdata):
+        flowdata.set_element_data(ElementDataDictionary(
+            self, {"cloud": json.dumps({"device": {"ismobile": True}})}))
+
+
+def location_engine():
+    engine = CloudEngine()
+    engine.datakey = "location"
+    return engine
+
+
+class MissingProductTests(unittest.TestCase):
+
+    def build(self):
+        logger = RecordingLogger()
+        builder = PipelineBuilder({"add_javascript_builder": False,
+                                   "use_setheader_properties": False})
+        builder.add_logger(logger)
+        engine = location_engine()
+        pipeline = builder.add(FakeCloudRequestEngine()).add(engine).build()
+        self.addCleanup(pipeline.close)
+        return pipeline, engine, logger
+
+    def testPipelineBuildsWithEmptyMetadata(self):
+        pipeline, engine, logger = self.build()
+        self.assertEqual({}, engine.get_properties())
+
+    def testMissingProductIsLoggedOnce(self):
+        pipeline, engine, logger = self.build()
+        missing = [entry for entry in logger.logged
+                   if "location" in entry[1]]
+        self.assertEqual(1, len(missing), logger.logged)
+        # The specification asks for the warning level.
+        self.assertEqual("warning", missing[0][0])
+
+    def testNothingIsLoggedOnEachResponse(self):
+        pipeline, engine, logger = self.build()
+        before = len(logger.logged)
+        for _ in range(3):
+            flowdata = pipeline.create_flowdata()
+            flowdata.process()
+            self.assertEqual(0, len(flowdata.errors))
+            self.assertEqual({}, flowdata.get("location").as_dictionary())
+        self.assertEqual(before, len(logger.logged), logger.logged)
+
+    def testEngineWithItsProductStillBuildsWithItsProperties(self):
+        logger = RecordingLogger()
+        builder = PipelineBuilder({"add_javascript_builder": False,
+                                   "use_setheader_properties": False})
+        builder.add_logger(logger)
+        engine = CloudEngine()
+        engine.datakey = "device"
+        pipeline = builder.add(FakeCloudRequestEngine()).add(engine).build()
+        self.addCleanup(pipeline.close)
+        self.assertEqual(["ismobile"], list(engine.get_properties()))
+        self.assertEqual([], logger.logged)
+
+
+if __name__ == "__main__":
+    unittest.main()