add get upa from object method

lib/SampleService/core/api_translation.py

@@ -27,7 +27,7 @@
 from SampleService.core.errors import MissingParameterError as _MissingParameterError
 from SampleService.core.errors import UnauthorizedError as _UnauthorizedError
 from SampleService.core.user import UserID as _UserID
-from SampleService.core.workspace import DataUnitID, UPA as _UPA
+from SampleService.core.workspace import DataUnitID, UPA
 
 ID = 'id'
 ''' The ID of a sample. '''
@@ -374,6 +374,7 @@ def create_data_link_params(params: Dict[str, Any]) -> Tuple[DataUnitID, SampleN
         1) The data unit ID that is the target of the link,
         2) The sample node that is the target of the link,
         3) A boolean that indicates whether the link should be updated if it already exists.
+    :raises MissingParameterError: if any of the required arguments are missing.
     :raises IllegalParameterError: if any of the arguments are illegal.
     '''
     _check_params(params)
@@ -384,15 +385,30 @@ def create_data_link_params(params: Dict[str, Any]) -> Tuple[DataUnitID, SampleN
         _cast(str, _check_string(params, 'node', True))
     )
     duid = DataUnitID(
-        _UPA(_cast(str, _check_string(params, 'upa', True))),
+        get_upa_from_object(params),
         _check_string(params, 'dataid'))
     return (duid, sna, bool(params.get('update')))
 
 
+def get_upa_from_object(params: Dict[str, Any]) -> UPA:
+    '''
+    Get an UPA from a parameter object. Expects the UPA in the key 'upa'.
+    :params params: the parameters.
+    :returns: the UPA.
+    :raises MissingParameterError: if the UPA is missing.
+    :raises IllegalParameterError: if the UPA is illegal.
+    '''
+    _check_params(params)
+    return UPA(_cast(str, _check_string(params, 'upa', True)))
+
+
 def _check_string(params: Dict[str, Any], key: str, required=False) -> Optional[str]:
     v = params.get(key)
-    if v is None and not required:
-        return None
+    if v is None:
+        if required:
+            raise _MissingParameterError(key)
+        else:
+            return None
     if type(v) != str:
         raise _IllegalParameterError(f'{key} key is not a string as required')
     return _cast(str, v)

test/core/api_translation_test.py

@@ -14,7 +14,8 @@
     get_static_key_metadata_params,
     create_data_link_params,
     get_datetime_from_epochmilliseconds_in_object,
-    links_to_dicts
+    links_to_dicts,
+    get_upa_from_object
 )
 from SampleService.core.data_link import DataLink
 from SampleService.core.sample import (
@@ -644,12 +645,18 @@ def test_create_data_link_params_fail_bad_args():
         IllegalParameterError('Illegal version argument: -1'))
     _create_data_link_params_fail(
         {'id': id_, 'version': 1},
+        MissingParameterError('node'))
+    _create_data_link_params_fail(
+        {'id': id_, 'version': 1, 'node': {'a': 'b'}},
         IllegalParameterError('node key is not a string as required'))
     _create_data_link_params_fail(
         {'id': id_, 'version': 1, 'node': 'foo\tbar'},
         IllegalParameterError('node contains control characters'))
     _create_data_link_params_fail(
         {'id': id_, 'version': 1, 'node': 'm'},
+        MissingParameterError('upa'))
+    _create_data_link_params_fail(
+        {'id': id_, 'version': 1, 'node': 'm', 'upa': 3.4},
         IllegalParameterError('upa key is not a string as required'))
     _create_data_link_params_fail(
         {'id': id_, 'version': 1, 'node': 'm', 'upa': '1/0/1'},
@@ -668,6 +675,25 @@ def _create_data_link_params_fail(params, expected):
     assert_exception_correct(got.value, expected)
 
 
+def test_get_upa_from_object():
+    assert get_upa_from_object({'upa': '1/1/1'}) == UPA('1/1/1')
+    assert get_upa_from_object({'upa': '8/3/2'}) == UPA('8/3/2')
+
+
+def test_get_upa_from_object_fail_bad_args():
+    _get_upa_from_object_fail(None, ValueError('params cannot be None'))
+    _get_upa_from_object_fail({}, MissingParameterError('upa'))
+    _get_upa_from_object_fail({'upa': '1/0/1'}, IllegalParameterError('1/0/1 is not a valid UPA'))
+    _get_upa_from_object_fail({'upa': 82}, IllegalParameterError(
+        'upa key is not a string as required'))
+
+
+def _get_upa_from_object_fail(params, expected):
+    with raises(Exception) as got:
+        get_upa_from_object(params)
+    assert_exception_correct(got.value, expected)
+
+
 def test_get_datetime_from_epochmilliseconds_in_object():
     gt = get_datetime_from_epochmilliseconds_in_object
     assert gt({}, 'foo') is None