Session State

Use the session_state to cache intermediate results in a database.

All Workflows come with a session_state dictionary that you can use to cache intermediate results. Provide your workflows with storage and a session_id to enable caching.

For example, you can use the SqlWorkflowStorage to cache results in a Sqlite database.

# Create the workflow
generate_blog_post = BlogPostGenerator(
    session_id="my-session-id",
    storage=SqlWorkflowStorage(
        table_name="generate_blog_post_workflows",
        db_file="tmp/workflows.db",
    ),
)

Then in the run() method, you can read from and add to the session_state as needed.

class BlogPostGenerator(Workflow):
    # ... agents
    def run(self, topic: str, use_cache: bool = True) -> Iterator[RunResponse]:
        # Read from the session state cache
        if use_cache and "blog_posts" in self.session_state:
            logger.info("Checking if cached blog post exists")
            for cached_blog_post in self.session_state["blog_posts"]:
                if cached_blog_post["topic"] == topic:
                    logger.info("Found cached blog post")
                    yield RunResponse(
                        run_id=self.run_id,
                        event=RunEvent.workflow_completed,
                        content=cached_blog_post["blog_post"],
                    )
                    return

        # ... generate the blog post

        # Save to session state for future runs
        if "blog_posts" not in self.session_state:
            self.session_state["blog_posts"] = []
        self.session_state["blog_posts"].append({"topic": topic, "blog_post": self.writer.run_response.content})

When the workflow starts, the session_state for that particular session_id is read from the database and when the workflow ends, the session_state is stored in the database.

You can always call self.write_to_storage() to save the session_state to the database at any time. Incase you need to abort the workflow but want to store the intermediate results.

View the Blog Post Generator for an example of how to use session state for caching.