Playground

The Playground is a dynamic interface designed for real-time interaction with LLMs, allowing users to chat, access memories, and monitor inputs and outputs. Here, users can directly prototype their models, making adjustments and observing different outcomes.

As long as you have an Input or Output component working, you can open it by clicking the Playground button. The Playground's window arrangement changes depending on what components are being used.

Run a flow in the playgound

When you run a flow in the Playground, Langflow calls the /build/{flow_id}/flow endpoint in chat.py. This call retrieves the flow data, builds a graph, and executes the graph. As each component (or node) is executed, the build_vertex function calls build_and_run, which may call the individual components' def_build method, if it exists. If a component doesn't have a def_build function, the build still returns a component.

The build function allows components to execute logic at runtime. For example, the Recursive character text splitter is a child of the LCTextSplitterComponent class. When text needs to be processed, the parent class's build method is called, which creates a RecursiveCharacterTextSplitter object and uses it to split the text according to the defined parameters. The split text is then passed on to the next component. This all occurs when the component is built.

View playground messages by session ID

When you send a message from the Playground interface, the interactions are stored in the Message Logs by session_id. A single flow can have multiple chats, and different flows can share the same chat. Each chat will have a different session_id.

To view messages by session_id within the Playground, click the menu of any chat session, and then select Message Logs.

Individual messages in chat memory can be edited or deleted. Modifying these memories influences the behavior of the chatbot responses.

To learn more about chat memories in Langflow, see Memory components.

Use custom Session IDs for multiple user interactions

session_id values are used to track user interactions in a flow. By default, if the session_id value is empty, it is set to the same value as the flow_id. In this case, every chat call uses the same session_id, and you effectively have one chat session.

The session_id value can be configured in the Advanced Settings of the Chat Input and Chat Output components.

To have more than one session in a single flow, pass a specific Session ID to a flow with the session_id parameter in the URL. All the components in the flow will automatically use this session_id value.

To post a message to a flow with a specific Session ID with curl, enter the following command:

_10

curl -X POST "http://127.0.0.1:7860/api/v1/run/$FLOW_ID" \

_10

-H 'Content-Type: application/json' \

_10

-d '{

_10

"session_id": "custom_session_123",

_10

"input_value": "message",

_10

"input_type": "chat",

_10

"output_type": "chat"

_10

}'

Check your flow's Playground. In addition to the messages stored for the Default Session, a new session is started with your custom Session ID.