Error checking when adding to blaze server.

blaze/server/server.py

@@ -50,11 +50,8 @@ def _get_option(option, options, default=_no_default):
             return default
 
         # Provides a more informative error message.
-        raise TypeError(
-            'The blaze api must be registered with {option}'.format(
-                option=option,
-            ),
-        )
+        msg = 'The blaze api must be registered with {option}'
+        raise TypeError(msg.format(option=option))
 
 
 def ensure_dir(path):
@@ -70,12 +67,9 @@ def _register_api(app, options, first_registration=False):
     Register the data with the blueprint.
     """
     _get_data.cache[app] = _get_option('data', options)
-    _get_format.cache[app] = dict(
-        (f.name, f) for f in _get_option('formats', options)
-    )
-    _get_auth.cache[app] = (
-        _get_option('authorization', options, None) or (lambda a: True)
-    )
+    _get_format.cache[app] = dict((f.name, f) for f in _get_option('formats', options))
+    _get_auth.cache[app] = (_get_option('authorization', options, None) or
+                            (lambda a: True))
     allow_profiler = _get_option('allow_profiler', options, False)
     profiler_output = _get_option('profiler_output', options, None)
     profile_by_default = _get_option('profile_by_default', options, False)
@@ -607,21 +601,46 @@ def log_time(start=time()):
 def addserver(payload, serial):
     """Add a data resource to the server.
 
-    The reuest should contain serialized MutableMapping (dictionary) like
-    object, and the server should already be hosting a MutableMapping
-    resource.
+    The request should contain serialized MutableMapping (dictionary) like
+    object, and the server should already be hosting a MutableMapping resource.
     """
+
     data = _get_data.cache[flask.current_app]
 
-    data_not_mm_msg = ("Cannot update blaze server data since its current data"
-                       " is a %s and not a mutable mapping (dictionary like).")
     if not isinstance(data, collections.MutableMapping):
+        data_not_mm_msg = ("Cannot update blaze server data since its current "
+                           "data is a %s and not a mutable mapping (dictionary "
+                           "like).")
         return (data_not_mm_msg % type(data), 422)
 
-    payload_not_mm_msg = ("Cannot update blaze server with a %s payload, since"
-                          " it is not a mutable mapping (dictionary like).")
-    if not isinstance(payload, collections.MutableMapping):
-        return (payload_not_mm_msg % type(payload), 422)
+    if not isinstance(payload, collections.Mapping):
+        payload_not_mm_msg = ("Need a dictionary-like payload; instead was "
+                              "given %s of type %s.")
+        return (payload_not_mm_msg % (payload, type(payload)), 422)
 
-    data.update(valmap(resource, payload))
-    return 'OK'
+    if len(payload) > 1:
+        error_msg = "Given more than one resource to add: %s"
+        return (error_msg % list(payload.keys()), 422)
+
+    [(name, resource_args)] = payload.items()
+
+    if name in data:
+        msg = "Cannot add dataset named %s, already exists on server."
+        return (msg % name, 409)
+
+    try:
+        data.update({name: resource(resource_args)})
+        # Force discovery of new dataset to check that the data is loadable.
+        ds = discover(data)
+        if name not in ds.dict:
+            raise ValueError("%s not added." % name)
+    except NotImplementedError as e:
+        error_msg = "Addition not supported:\n%s: %s" 
+        return (error_msg % (type(e).__name__, e),
+                422)
+    except Exception as e:
+        error_msg = "Addition failed with message:\n%s: %s" 
+        return (error_msg % (type(e).__name__, e),
+                422)
+
+    return ('OK', 200)