feat: add MCP support (#20716)
Co-authored-by: QuantumGhost <obelisk.reg+git@gmail.com>
This commit is contained in:
Novice
224
api/core/mcp/server/streamable_http.py
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224
api/core/mcp/server/streamable_http.py
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import json
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import logging
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from collections.abc import Mapping
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from typing import Any, cast
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from configs import dify_config
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from controllers.web.passport import generate_session_id
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from core.app.app_config.entities import VariableEntity, VariableEntityType
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from core.app.entities.app_invoke_entities import InvokeFrom
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from core.app.features.rate_limiting.rate_limit import RateLimitGenerator
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from core.mcp import types
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from core.mcp.types import INTERNAL_ERROR, INVALID_PARAMS, METHOD_NOT_FOUND
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from core.mcp.utils import create_mcp_error_response
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from core.model_runtime.utils.encoders import jsonable_encoder
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from extensions.ext_database import db
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from models.model import App, AppMCPServer, AppMode, EndUser
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from services.app_generate_service import AppGenerateService
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"""
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Apply to MCP HTTP streamable server with stateless http
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"""
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logger = logging.getLogger(__name__)
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class MCPServerStreamableHTTPRequestHandler:
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def __init__(
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self, app: App, request: types.ClientRequest | types.ClientNotification, user_input_form: list[VariableEntity]
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):
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self.app = app
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self.request = request
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mcp_server = db.session.query(AppMCPServer).filter(AppMCPServer.app_id == self.app.id).first()
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if not mcp_server:
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raise ValueError("MCP server not found")
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self.mcp_server: AppMCPServer = mcp_server
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self.end_user = self.retrieve_end_user()
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self.user_input_form = user_input_form
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@property
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def request_type(self):
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return type(self.request.root)
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@property
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def parameter_schema(self):
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parameters, required = self._convert_input_form_to_parameters(self.user_input_form)
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if self.app.mode in {AppMode.COMPLETION.value, AppMode.WORKFLOW.value}:
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return {
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"type": "object",
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"properties": parameters,
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"required": required,
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}
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return {
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"type": "object",
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"properties": {
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"query": {"type": "string", "description": "User Input/Question content"},
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**parameters,
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},
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"required": ["query", *required],
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}
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@property
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def capabilities(self):
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return types.ServerCapabilities(
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tools=types.ToolsCapability(listChanged=False),
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)
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def response(self, response: types.Result | str):
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if isinstance(response, str):
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sse_content = f"event: ping\ndata: {response}\n\n".encode()
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yield sse_content
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return
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json_response = types.JSONRPCResponse(
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jsonrpc="2.0",
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id=(self.request.root.model_extra or {}).get("id", 1),
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result=response.model_dump(by_alias=True, mode="json", exclude_none=True),
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)
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json_data = json.dumps(jsonable_encoder(json_response))
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sse_content = f"event: message\ndata: {json_data}\n\n".encode()
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yield sse_content
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def error_response(self, code: int, message: str, data=None):
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request_id = (self.request.root.model_extra or {}).get("id", 1) or 1
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return create_mcp_error_response(request_id, code, message, data)
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def handle(self):
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handle_map = {
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types.InitializeRequest: self.initialize,
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types.ListToolsRequest: self.list_tools,
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types.CallToolRequest: self.invoke_tool,
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types.InitializedNotification: self.handle_notification,
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}
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try:
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if self.request_type in handle_map:
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return self.response(handle_map[self.request_type]())
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else:
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return self.error_response(METHOD_NOT_FOUND, f"Method not found: {self.request_type}")
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except ValueError as e:
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logger.exception("Invalid params")
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return self.error_response(INVALID_PARAMS, str(e))
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except Exception as e:
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logger.exception("Internal server error")
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return self.error_response(INTERNAL_ERROR, f"Internal server error: {str(e)}")
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def handle_notification(self):
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return "ping"
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def initialize(self):
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request = cast(types.InitializeRequest, self.request.root)
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client_info = request.params.clientInfo
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clinet_name = f"{client_info.name}@{client_info.version}"
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if not self.end_user:
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end_user = EndUser(
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tenant_id=self.app.tenant_id,
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app_id=self.app.id,
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type="mcp",
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name=clinet_name,
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session_id=generate_session_id(),
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external_user_id=self.mcp_server.id,
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)
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db.session.add(end_user)
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db.session.commit()
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return types.InitializeResult(
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protocolVersion=types.SERVER_LATEST_PROTOCOL_VERSION,
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capabilities=self.capabilities,
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serverInfo=types.Implementation(name="Dify", version=dify_config.project.version),
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instructions=self.mcp_server.description,
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)
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def list_tools(self):
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if not self.end_user:
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raise ValueError("User not found")
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return types.ListToolsResult(
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tools=[
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types.Tool(
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name=self.app.name,
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description=self.mcp_server.description,
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inputSchema=self.parameter_schema,
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)
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],
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)
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def invoke_tool(self):
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if not self.end_user:
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raise ValueError("User not found")
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request = cast(types.CallToolRequest, self.request.root)
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args = request.params.arguments
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if not args:
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raise ValueError("No arguments provided")
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if self.app.mode in {AppMode.WORKFLOW.value}:
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args = {"inputs": args}
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elif self.app.mode in {AppMode.COMPLETION.value}:
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args = {"query": "", "inputs": args}
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else:
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args = {"query": args["query"], "inputs": {k: v for k, v in args.items() if k != "query"}}
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response = AppGenerateService.generate(
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self.app,
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self.end_user,
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args,
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InvokeFrom.SERVICE_API,
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streaming=self.app.mode == AppMode.AGENT_CHAT.value,
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)
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answer = ""
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if isinstance(response, RateLimitGenerator):
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for item in response.generator:
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data = item
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if isinstance(data, str) and data.startswith("data: "):
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try:
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json_str = data[6:].strip()
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parsed_data = json.loads(json_str)
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if parsed_data.get("event") == "agent_thought":
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answer += parsed_data.get("thought", "")
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except json.JSONDecodeError:
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continue
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if isinstance(response, Mapping):
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if self.app.mode in {
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AppMode.ADVANCED_CHAT.value,
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AppMode.COMPLETION.value,
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AppMode.CHAT.value,
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AppMode.AGENT_CHAT.value,
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}:
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answer = response["answer"]
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elif self.app.mode in {AppMode.WORKFLOW.value}:
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answer = json.dumps(response["data"]["outputs"], ensure_ascii=False)
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else:
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raise ValueError("Invalid app mode")
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# Not support image yet
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return types.CallToolResult(content=[types.TextContent(text=answer, type="text")])
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def retrieve_end_user(self):
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return (
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db.session.query(EndUser)
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.filter(EndUser.external_user_id == self.mcp_server.id, EndUser.type == "mcp")
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.first()
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)
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def _convert_input_form_to_parameters(self, user_input_form: list[VariableEntity]):
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parameters: dict[str, dict[str, Any]] = {}
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required = []
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for item in user_input_form:
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parameters[item.variable] = {}
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if item.type in (
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VariableEntityType.FILE,
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VariableEntityType.FILE_LIST,
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VariableEntityType.EXTERNAL_DATA_TOOL,
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):
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continue
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if item.required:
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required.append(item.variable)
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# if the workflow republished, the parameters not changed
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# we should not raise error here
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try:
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description = self.mcp_server.parameters_dict[item.variable]
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except KeyError:
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description = ""
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parameters[item.variable]["description"] = description
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if item.type in (VariableEntityType.TEXT_INPUT, VariableEntityType.PARAGRAPH):
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parameters[item.variable]["type"] = "string"
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elif item.type == VariableEntityType.SELECT:
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parameters[item.variable]["type"] = "string"
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parameters[item.variable]["enum"] = item.options
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elif item.type == VariableEntityType.NUMBER:
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parameters[item.variable]["type"] = "float"
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return parameters, required
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