Feat: conversation variable & variable assigner node (#7222)

Signed-off-by: -LAN- <laipz8200@outlook.com>
Co-authored-by: Joel <iamjoel007@gmail.com>
Co-authored-by: -LAN- <laipz8200@outlook.com>

api/core/workflow/nodes/base_node.py

@@ -8,6 +8,7 @@ from core.workflow.callbacks.base_workflow_callback import WorkflowCallback
 from core.workflow.entities.base_node_data_entities import BaseIterationState, BaseNodeData
 from core.workflow.entities.node_entities import NodeRunResult, NodeType
 from core.workflow.entities.variable_pool import VariablePool
+from models import WorkflowNodeExecutionStatus
 
 
 class UserFrom(Enum):
@@ -91,14 +92,19 @@ class BaseNode(ABC):
         :param variable_pool: variable pool
         :return:
         """
-        result = self._run(
-            variable_pool=variable_pool
-        )
+        try:
+            result = self._run(
+                variable_pool=variable_pool
+            )
+            self.node_run_result = result
+            return result
+        except Exception as e:
+            return NodeRunResult(
+                status=WorkflowNodeExecutionStatus.FAILED,
+                error=str(e),
+            )
 
-        self.node_run_result = result
-        return result
-
-    def publish_text_chunk(self, text: str, value_selector: list[str] = None) -> None:
+    def publish_text_chunk(self, text: str, value_selector: list[str] | None = None) -> None:
         """
         Publish text chunk
         :param text: chunk text

api/core/workflow/nodes/variable_assigner/__init__.py

@@ -0,0 +1,109 @@
+from collections.abc import Sequence
+from enum import Enum
+from typing import Optional, cast
+
+from sqlalchemy import select
+from sqlalchemy.orm import Session
+
+from core.app.segments import SegmentType, Variable, factory
+from core.workflow.entities.base_node_data_entities import BaseNodeData
+from core.workflow.entities.node_entities import NodeRunResult, NodeType
+from core.workflow.entities.variable_pool import VariablePool
+from core.workflow.nodes.base_node import BaseNode
+from extensions.ext_database import db
+from models import ConversationVariable, WorkflowNodeExecutionStatus
+
+
+class VariableAssignerNodeError(Exception):
+    pass
+
+
+class WriteMode(str, Enum):
+    OVER_WRITE = 'over-write'
+    APPEND = 'append'
+    CLEAR = 'clear'
+
+
+class VariableAssignerData(BaseNodeData):
+    title: str = 'Variable Assigner'
+    desc: Optional[str] = 'Assign a value to a variable'
+    assigned_variable_selector: Sequence[str]
+    write_mode: WriteMode
+    input_variable_selector: Sequence[str]
+
+
+class VariableAssignerNode(BaseNode):
+    _node_data_cls: type[BaseNodeData] = VariableAssignerData
+    _node_type: NodeType = NodeType.CONVERSATION_VARIABLE_ASSIGNER
+
+    def _run(self, variable_pool: VariablePool) -> NodeRunResult:
+        data = cast(VariableAssignerData, self.node_data)
+
+        # Should be String, Number, Object, ArrayString, ArrayNumber, ArrayObject
+        original_variable = variable_pool.get(data.assigned_variable_selector)
+        if not isinstance(original_variable, Variable):
+            raise VariableAssignerNodeError('assigned variable not found')
+
+        match data.write_mode:
+            case WriteMode.OVER_WRITE:
+                income_value = variable_pool.get(data.input_variable_selector)
+                if not income_value:
+                    raise VariableAssignerNodeError('input value not found')
+                updated_variable = original_variable.model_copy(update={'value': income_value.value})
+
+            case WriteMode.APPEND:
+                income_value = variable_pool.get(data.input_variable_selector)
+                if not income_value:
+                    raise VariableAssignerNodeError('input value not found')
+                updated_value = original_variable.value + [income_value.value]
+                updated_variable = original_variable.model_copy(update={'value': updated_value})
+
+            case WriteMode.CLEAR:
+                income_value = get_zero_value(original_variable.value_type)
+                updated_variable = original_variable.model_copy(update={'value': income_value.to_object()})
+
+            case _:
+                raise VariableAssignerNodeError(f'unsupported write mode: {data.write_mode}')
+
+        # Over write the variable.
+        variable_pool.add(data.assigned_variable_selector, updated_variable)
+
+        # Update conversation variable.
+        # TODO: Find a better way to use the database.
+        conversation_id = variable_pool.get(['sys', 'conversation_id'])
+        if not conversation_id:
+            raise VariableAssignerNodeError('conversation_id not found')
+        update_conversation_variable(conversation_id=conversation_id.text, variable=updated_variable)
+
+        return NodeRunResult(
+            status=WorkflowNodeExecutionStatus.SUCCEEDED,
+            inputs={
+                'value': income_value.to_object(),
+            },
+        )
+
+
+def update_conversation_variable(conversation_id: str, variable: Variable):
+    stmt = select(ConversationVariable).where(
+        ConversationVariable.id == variable.id, ConversationVariable.conversation_id == conversation_id
+    )
+    with Session(db.engine) as session:
+        row = session.scalar(stmt)
+        if not row:
+            raise VariableAssignerNodeError('conversation variable not found in the database')
+        row.data = variable.model_dump_json()
+        session.commit()
+
+
+def get_zero_value(t: SegmentType):
+    match t:
+        case SegmentType.ARRAY_OBJECT | SegmentType.ARRAY_STRING | SegmentType.ARRAY_NUMBER:
+            return factory.build_segment([])
+        case SegmentType.OBJECT:
+            return factory.build_segment({})
+        case SegmentType.STRING:
+            return factory.build_segment('')
+        case SegmentType.NUMBER:
+            return factory.build_segment(0)
+        case _:
+            raise VariableAssignerNodeError(f'unsupported variable type: {t}')