Remove attribute from an element (#19)

+add docstrings for QuaCalNode

close #20

entropylab_qpudb/_entropy_cal.py

@@ -6,11 +6,12 @@
 from itertools import count
 from typing import Callable, List, Optional, Union, Iterable, Set
 
-from entropylab_qpudb._quaconfig import QuaConfig
 from entropylab.api.execution import EntropyContext
 from entropylab.api.graph import Node
 from entropylab.graph_experiment import PyNode
 
+from entropylab_qpudb._quaconfig import QuaConfig
+
 
 class AncestorRunStrategy(enum.Enum):
     RunAll = 1
@@ -142,12 +143,34 @@ def get_patches(config):
 
     @abstractmethod
     def prepare_config(self, config: QuaConfig, context: EntropyContext):
+        """
+            Gets a config, and modify it in place (modifies the QuaConfig object)
+            with necessary changes for the node execution
+        :param config:
+        :param context:
+        """
         pass
 
     @abstractmethod
     def run_program(self, config, context: EntropyContext):
+        """
+            defines the node program/measurement.
+            If AncestorRunStrategy.RunOnlyLast is used, only the program
+            of the last node will be executed.
+        :param config:
+        :param context:
+        """
         pass
 
     @abstractmethod
     def update_config(self, config: QuaConfig, context: EntropyContext):
+        """
+            Updates the config with needed changes in place
+            (modifies the QuaConfig object)
+            Changes here will affect the following nodes.
+        :param config:
+        :param context:
+        """
+        pass
+
         pass

entropylab_qpudb/_qpudatabase.py

@@ -297,6 +297,23 @@ def add_attribute(
             )
             root["elements"]._p_changed = True
 
+    def remove_attribute(self, element: str, attribute: str) -> None:
+        """
+        remove an existing attribute.
+
+        :raises: AttributeError if attribute does not exist.
+        :param element: the name of the element
+        :param attribute: the name of the atrribute to remove
+        """
+        root = self._con.root()
+        if attribute not in root["elements"][element]:
+            raise AttributeError(
+                f"attribute {attribute} does not exist for element {element}"
+            )
+        else:
+            del root["elements"][element][attribute]
+            root["elements"]._p_changed = True
+
     def add_element(self, element: str) -> None:
         """
         :raises: AttributeError if element already exists.

entropylab_qpudb/tests/test_qpudatabase.py

@@ -353,6 +353,26 @@ def test_add_elements_persistence(testdb):
         assert db.get("q_new", "p_new").value == "something"
 
 
+def test_add_and_remove_elements_persistence(testdb):
+    with _QpuDatabaseConnectionBase(testdb) as db:
+        db.add_element("q_new")
+        db.add_attribute("q_new", "p_new", "something")
+        db.commit()
+        db.remove_attribute("q_new", "p_new")
+        db.commit()
+
+    with _QpuDatabaseConnectionBase(testdb) as db:
+        with pytest.raises(AttributeError):
+            db.get("q_new", "p_new")
+
+    with _QpuDatabaseConnectionBase(testdb) as db:
+        db.restore_from_history(1)
+        assert db.get("q_new", "p_new").value == "something"
+        db.restore_from_history(2)
+        with pytest.raises(AttributeError):
+            db.get("q_new", "p_new")
+
+
 def test_with_resolver(testdb, simp_resolver):
     with QpuDatabaseConnection(testdb, simp_resolver) as db:
         db.update_q(1, "p1", 555)