deepset-ai · silvanocerza · Sep 4, 2023 · Aug 31, 2023 · Aug 31, 2023 · Aug 31, 2023
diff --git a/canals/component/component.py b/canals/component/component.py
@@ -94,17 +94,6 @@ def run(self, **kwargs) -> Dict[str, Any]:
         or with `component.set_output_types()` if dynamic.
         """
 
-    def to_dict(self) -> Dict[str, Any]:
-        """
-        Serializes the component to a dictionary.
-        """
-
-    @classmethod
-    def from_dict(cls, data: Dict[str, Any]) -> "Component":
-        """
-        Deserializes the component from a dictionary.
-        """
-
 
 class _Component:
     """
@@ -234,16 +223,6 @@ def _component(self, class_):
             raise ComponentError(f"{class_.__name__} must have a 'run()' method. See the docs for more information.")
         run_signature = inspect.signature(class_.run)
 
-        if not hasattr(class_, "to_dict"):
-            raise ComponentError(
-                f"{class_.__name__} must have a 'to_dict()' method. See the docs for more information."
-            )
-
-        if not hasattr(class_, "from_dict"):
-            raise ComponentError(
-                f"{class_.__name__} must have a 'from_dict()' method. See the docs for more information."
-            )
-
         # Create the input sockets
         class_.run.__canals_input__ = {
             param: {

diff --git a/canals/errors.py b/canals/errors.py
@@ -39,3 +39,7 @@ class ComponentDeserializationError(Exception):
 
 class DeserializationError(Exception):
     pass
+
+
+class SerializationError(Exception):
+    pass
diff --git a/canals/pipeline/draw/mermaid.py b/canals/pipeline/draw/mermaid.py
@@ -10,6 +10,7 @@
 
 from canals.errors import PipelineDrawingError
 from canals.utils import _type_name
+from canals.serialization import component_to_dict
 
 logger = logging.getLogger(__name__)
 
@@ -69,7 +70,7 @@ def _to_mermaid_text(graph: networkx.MultiDiGraph) -> str:
     for name, comp in graph.nodes(data="instance"):
         if name in ["input", "output"]:
             continue
-        data = comp.to_dict()
+        data = component_to_dict(comp)
         params = [f"{k}={json.dumps(v)}" for k, v in data.get("init_parameters", {}).items()]
         init_params[name] = ",<br>".join(params)
     states = "\n".join(

diff --git a/canals/pipeline/pipeline.py b/canals/pipeline/pipeline.py
@@ -26,6 +26,7 @@
 from canals.pipeline.validation import _validate_pipeline_input
 from canals.pipeline.connections import _parse_connection_name, _find_unambiguous_connection
 from canals.utils import _type_name
+from canals.serialization import component_to_dict, component_from_dict
 
 logger = logging.getLogger(__name__)
 
@@ -84,7 +85,10 @@ def to_dict(self) -> Dict[str, Any]:
         Returns this Pipeline instance as a dictionary.
         This is meant to be an intermediate representation but it can be also used to save a pipeline to file.
         """
-        components = {name: instance.to_dict() for name, instance in self.graph.nodes(data="instance")}
+        components = {}
+        for name, instance in self.graph.nodes(data="instance"):
+            components[name] = component_to_dict(instance)
+
         connections = []
         for sender, receiver, sockets in self.graph.edges:
             (sender_socket, receiver_socket) = sockets.split("/")
@@ -152,7 +156,8 @@ def from_dict(cls, data: Dict[str, Any], **kwargs) -> "Pipeline":
                 if component_data["type"] not in component.registry:
                     raise PipelineError(f"Component '{component_data['type']}' not imported.")
                 # Create a new one
-                instance = component.registry[component_data["type"]].from_dict(component_data)
+                component_class = component.registry[component_data["type"]]
+                instance = component_from_dict(component_class, component_data)
             pipe.add_component(name=name, instance=instance)
 
         for connection in data.get("connections", []):

diff --git a/canals/serialization.py b/canals/serialization.py
@@ -1,9 +1,50 @@
 # SPDX-FileCopyrightText: 2022-present deepset GmbH <info@deepset.ai>
 #
 # SPDX-License-Identifier: Apache-2.0
+import inspect
 from typing import Type, Dict, Any
 
-from canals.errors import DeserializationError
+from canals.errors import DeserializationError, SerializationError
+
+
+def component_to_dict(obj: Any) -> Dict[str, Any]:
+    """
+    The marshaller used by the Pipeline. If a `to_dict` method is present in the
+    component instance, that will be used instead of the default method.
+    """
+    if hasattr(obj, "to_dict"):
+        return obj.to_dict()
+
+    init_parameters = {}
+    for name, param in inspect.signature(obj.__init__).parameters.items():
+        try:
+            # This only works if the Component constructor assigns the init
+            # parameter to an instance variable or property with the same name
+            param_value = getattr(obj, name)
+        except AttributeError as e:
+            # If the parameter doesn't have a default value, raise an error
+            if param.default is param.empty:
+                raise SerializationError(
+                    f"Cannot determined the value of the init parameter '{name}'. "
+                    f"You can fix this error by assigning 'self.{name} = {name}' or adding a "
+                    f"custom serialization method 'to_dict' to the class {obj.__class__.__name__}"
+                ) from e
+            # In case the init parameter was not assigned, we use the default value
+            param_value = param.default
+        init_parameters[name] = param_value
+
+    return default_to_dict(obj, **init_parameters)
+
+
+def component_from_dict(cls: Type[object], data: Dict[str, Any]) -> Any:
+    """
+    The unmarshaller used by the Pipeline. If a `from_dict` method is present in the
+    component instance, that will be used instead of the default method.
+    """
+    if hasattr(cls, "from_dict"):
+        return cls.from_dict(data)
+
+    return default_from_dict(cls, data)
 
 
 def default_to_dict(obj: Any, **init_parameters) -> Dict[str, Any]:

diff --git a/pyproject.toml b/pyproject.toml
@@ -91,4 +91,5 @@ disable = [
   "line-too-long",
   "missing-class-docstring",
   "missing-module-docstring",
+  "too-few-public-methods",
 ]
diff --git a/sample_components/greet.py b/sample_components/greet.py
@@ -1,11 +1,10 @@
 # SPDX-FileCopyrightText: 2022-present deepset GmbH <info@deepset.ai>
 #
 # SPDX-License-Identifier: Apache-2.0
-from typing import Optional, Dict, Any
+from typing import Optional
 import logging
 
 from canals import component
-from canals.serialization import default_to_dict, default_from_dict
 
 
 logger = logging.getLogger(__name__)
@@ -31,13 +30,6 @@ def __init__(
         self.message = message
         self.log_level = log_level
 
-    def to_dict(self) -> Dict[str, Any]:  # pylint: disable=missing-function-docstring
-        return default_to_dict(self, message=self.message, log_level=self.log_level)
-
-    @classmethod
-    def from_dict(cls, data: Dict[str, Any]) -> "Greet":  # pylint: disable=missing-function-docstring
-        return default_from_dict(cls, data)
-
     @component.output_types(value=int)
     def run(self, value: int, message: Optional[str] = None, log_level: Optional[str] = None):
         """

diff --git a/test/sample_components/test_greet.py b/test/sample_components/test_greet.py
@@ -4,11 +4,12 @@
 import logging
 
 from sample_components import Greet
+from canals.serialization import component_to_dict, component_from_dict
 
 
 def test_to_dict():
     component = Greet()
-    res = component.to_dict()
+    res = component_to_dict(component)
     assert res == {
         "type": "Greet",
         "init_parameters": {
@@ -20,7 +21,7 @@ def test_to_dict():
 
 def test_to_dict_with_custom_parameters():
     component = Greet(message="My message", log_level="ERROR")
-    res = component.to_dict()
+    res = component_to_dict(component)
     assert res == {
         "type": "Greet",
         "init_parameters": {
@@ -35,7 +36,7 @@ def test_from_dict():
         "type": "Greet",
         "init_parameters": {},
     }
-    component = Greet.from_dict(data)
+    component = component_from_dict(Greet, data)
     assert component.message == "\nGreeting component says: Hi! The value is {value}\n"
     assert component.log_level == "INFO"
 
@@ -45,7 +46,7 @@ def test_from_with_custom_parameters():
         "type": "Greet",
         "init_parameters": {"message": "My message", "log_level": "ERROR"},
     }
-    component = Greet.from_dict(data)
+    component = component_from_dict(Greet, data)
     assert component.message == "My message"
     assert component.log_level == "ERROR"
-Original file line number
+Diff line change
@@ Expand Up / @@ -39,3 +39,7 @@ class ComponentDeserializationError(Exception): @@
     class DeserializationError(Exception):
         pass
+    class SerializationError(Exception):
+        pass