The list action node adds methods to extract specific list objects (#10421)

Co-authored-by: luowei <glpat-EjySCyNjWiLqAED-YmwM>
Co-authored-by: crazywoola <427733928@qq.com>
Co-authored-by: crazywoola <100913391+crazywoola@users.noreply.github.com>

api/core/workflow/nodes/list_operator/entities.py

@@ -49,8 +49,14 @@ class Limit(BaseModel):
     size: int = -1
 
 
+class ExtractConfig(BaseModel):
+    enabled: bool = False
+    serial: str = "1"
+
+
 class ListOperatorNodeData(BaseNodeData):
     variable: Sequence[str] = Field(default_factory=list)
     filter_by: FilterBy
     order_by: OrderBy
     limit: Limit
+    extract_by: ExtractConfig

api/core/workflow/nodes/list_operator/node.py

@@ -58,6 +58,10 @@ class ListOperatorNode(BaseNode[ListOperatorNodeData]):
             if self.node_data.filter_by.enabled:
                 variable = self._apply_filter(variable)
 
+            # Extract
+            if self.node_data.extract_by.enabled:
+                variable = self._extract_slice(variable)
+
             # Order
             if self.node_data.order_by.enabled:
                 variable = self._apply_order(variable)
@@ -140,6 +144,16 @@ class ListOperatorNode(BaseNode[ListOperatorNodeData]):
         result = variable.value[: self.node_data.limit.size]
         return variable.model_copy(update={"value": result})
 
+    def _extract_slice(
+        self, variable: Union[ArrayFileSegment, ArrayNumberSegment, ArrayStringSegment]
+    ) -> Union[ArrayFileSegment, ArrayNumberSegment, ArrayStringSegment]:
+        value = int(self.graph_runtime_state.variable_pool.convert_template(self.node_data.extract_by.serial).text) - 1
+        if len(variable.value) > int(value):
+            result = variable.value[value]
+        else:
+            result = ""
+        return variable.model_copy(update={"value": [result]})
+
 
 def _get_file_extract_number_func(*, key: str) -> Callable[[File], int]:
     match key: