🚀 feat(api): add support for frontend_node in validate_prompt endpoint

✨ feat(base.py): add frontend_node parameter to ValidatePromptRequest and PromptValidationResponse models
The validate_prompt endpoint now accepts a frontend_node parameter in the ValidatePromptRequest model. This parameter is used to add input variables to the frontend_node's template fields and custom fields. The PromptValidationResponse model now includes the frontend_node parameter to return the updated frontend_node object.

src/backend/langflow/api/v1/base.py

@@ -1,3 +1,4 @@
+from langflow.template.frontend_node.base import FrontendNode
 from pydantic import BaseModel, validator
 
 from langflow.interface.utils import extract_input_variables_from_prompt
@@ -12,8 +13,9 @@ class Code(BaseModel):
     code: str
 
 
-class Prompt(BaseModel):
+class ValidatePromptRequest(BaseModel):
     template: str
+    frontend_node: FrontendNode
 
 
 # Build ValidationResponse class for {"imports": {"errors": []}, "function": {"errors": []}}
@@ -32,6 +34,7 @@ class CodeValidationResponse(BaseModel):
 
 class PromptValidationResponse(BaseModel):
     input_variables: list
+    frontend_node: FrontendNode
 
 
 INVALID_CHARACTERS = {
@@ -66,7 +69,7 @@ def validate_prompt(template: str):
     # if len(input_variables) > 1:
     #     # If there's more than one input variable
 
-    return PromptValidationResponse(input_variables=input_variables)
+    return input_variables
 
 
 def check_input_variables(input_variables: list):

src/backend/langflow/api/v1/validate.py

@@ -3,10 +3,11 @@ from fastapi import APIRouter, HTTPException
 from langflow.api.v1.base import (
     Code,
     CodeValidationResponse,
-    Prompt,
+    ValidatePromptRequest,
     PromptValidationResponse,
     validate_prompt,
 )
+from langflow.template.field.base import TemplateField
 from langflow.utils.logger import logger
 from langflow.utils.validate import validate_code
 
@@ -27,9 +28,24 @@ def post_validate_code(code: Code):
 
 
 @router.post("/prompt", status_code=200, response_model=PromptValidationResponse)
-def post_validate_prompt(prompt: Prompt):
+def post_validate_prompt(prompt: ValidatePromptRequest):
     try:
-        return validate_prompt(prompt.template)
+        input_variables = validate_prompt(prompt.template)
+        for variable in input_variables:
+            try:
+                template_field = TemplateField(
+                    name=variable, field_type="str", show=True, advanced=False
+                )
+                prompt.frontend_node.template.fields.append(template_field)
+                prompt.frontend_node.custom_fields.append(variable)
+            except Exception as exc:
+                logger.exception(exc)
+                raise HTTPException(status_code=500, detail=str(exc)) from exc
+
+        return PromptValidationResponse(
+            input_variables=input_variables,
+            frontend_node=prompt.frontend_node,
+        )
     except Exception as e:
         logger.exception(e)
         raise HTTPException(status_code=500, detail=str(e)) from e