构建你的第一个 Flow

crewai create flow guide_creator_flow
cd guide_creator_flow

guide_creator_flow/
├── .gitignore
├── pyproject.toml
├── README.md
├── .env
├── main.py
├── crews/
│   └── poem_crew/
│       ├── config/
│       │   ├── agents.yaml
│       │   └── tasks.yaml
│       └── poem_crew.py
└── tools/
    └── custom_tool.py

crewai flow add-crew content-crew

# src/guide_creator_flow/crews/content_crew/config/agents.yaml
content_writer:
  role: >
    Educational Content Writer
  goal: >
    Create engaging, informative content that thoroughly explains the assigned topic
    and provides valuable insights to the reader
  backstory: >
    You are a talented educational writer with expertise in creating clear, engaging
    content. You have a gift for explaining complex concepts in accessible language
    and organizing information in a way that helps readers build their understanding.
  llm: provider/model-id  # e.g. openai/gpt-4o, google/gemini-2.0-flash, anthropic/claude...

content_reviewer:
  role: >
    Educational Content Reviewer and Editor
  goal: >
    Ensure content is accurate, comprehensive, well-structured, and maintains
    consistency with previously written sections
  backstory: >
    You are a meticulous editor with years of experience reviewing educational
    content. You have an eye for detail, clarity, and coherence. You excel at
    improving content while maintaining the original author's voice and ensuring
    consistent quality across multiple sections.
  llm: provider/model-id  # e.g. openai/gpt-4o, google/gemini-2.0-flash, anthropic/claude...

# src/guide_creator_flow/crews/content_crew/config/tasks.yaml
write_section_task:
  description: >
    Write a comprehensive section on the topic: "{section_title}"

    Section description: {section_description}
    Target audience: {audience_level} level learners

    Your content should:
    1. Begin with a brief introduction to the section topic
    2. Explain all key concepts clearly with examples
    3. Include practical applications or exercises where appropriate
    4. End with a summary of key points
    5. Be approximately 500-800 words in length

    Format your content in Markdown with appropriate headings, lists, and emphasis.

    Previously written sections:
    {previous_sections}

    Make sure your content maintains consistency with previously written sections
    and builds upon concepts that have already been explained.
  expected_output: >
    A well-structured, comprehensive section in Markdown format that thoroughly
    explains the topic and is appropriate for the target audience.
  agent: content_writer

review_section_task:
  description: >
    Review and improve the following section on "{section_title}":

    {draft_content}

    Target audience: {audience_level} level learners

    Previously written sections:
    {previous_sections}

    Your review should:
    1. Fix any grammatical or spelling errors
    2. Improve clarity and readability
    3. Ensure content is comprehensive and accurate
    4. Verify consistency with previously written sections
    5. Enhance the structure and flow
    6. Add any missing key information

    Provide the improved version of the section in Markdown format.
  expected_output: >
    An improved, polished version of the section that maintains the original
    structure but enhances clarity, accuracy, and consistency.
  agent: content_reviewer
  context:
    - write_section_task

# src/guide_creator_flow/crews/content_crew/content_crew.py
from crewai import Agent, Crew, Process, Task
from crewai.project import CrewBase, agent, crew, task
from crewai.agents.agent_builder.base_agent import BaseAgent
from typing import List

@CrewBase
class ContentCrew():
    """Content writing crew"""

    agents: List[BaseAgent]
    tasks: List[Task]

    @agent
    def content_writer(self) -> Agent:
        return Agent(
            config=self.agents_config['content_writer'], # type: ignore[index]
            verbose=True
        )

    @agent
    def content_reviewer(self) -> Agent:
        return Agent(
            config=self.agents_config['content_reviewer'], # type: ignore[index]
            verbose=True
        )

    @task
    def write_section_task(self) -> Task:
        return Task(
            config=self.tasks_config['write_section_task'] # type: ignore[index]
        )

    @task
    def review_section_task(self) -> Task:
        return Task(
            config=self.tasks_config['review_section_task'], # type: ignore[index]
            context=[self.write_section_task()]
        )

    @crew
    def crew(self) -> Crew:
        """Creates the content writing crew"""
        return Crew(
            agents=self.agents,
            tasks=self.tasks,
            process=Process.sequential,
            verbose=True,
        )

#!/usr/bin/env python
import json
import os
from typing import List, Dict
from pydantic import BaseModel, Field
from crewai import LLM
from crewai.flow.flow import Flow, listen, start
from guide_creator_flow.crews.content_crew.content_crew import ContentCrew

# Define our models for structured data
class Section(BaseModel):
    title: str = Field(description="Title of the section")
    description: str = Field(description="Brief description of what the section should cover")

class GuideOutline(BaseModel):
    title: str = Field(description="Title of the guide")
    introduction: str = Field(description="Introduction to the topic")
    target_audience: str = Field(description="Description of the target audience")
    sections: List[Section] = Field(description="List of sections in the guide")
    conclusion: str = Field(description="Conclusion or summary of the guide")

# Define our flow state
class GuideCreatorState(BaseModel):
    topic: str = ""
    audience_level: str = ""
    guide_outline: GuideOutline = None
    sections_content: Dict[str, str] = {}

class GuideCreatorFlow(Flow[GuideCreatorState]):
    """Flow for creating a comprehensive guide on any topic"""

    @start()
    def get_user_input(self):
        """Get input from the user about the guide topic and audience"""
        print("\n=== Create Your Comprehensive Guide ===\n")

        # Get user input
        self.state.topic = input("What topic would you like to create a guide for? ")

        # Get audience level with validation
        while True:
            audience = input("Who is your target audience? (beginner/intermediate/advanced) ").lower()
            if audience in ["beginner", "intermediate", "advanced"]:
                self.state.audience_level = audience
                break
            print("Please enter 'beginner', 'intermediate', or 'advanced'")

        print(f"\nCreating a guide on {self.state.topic} for {self.state.audience_level} audience...\n")
        return self.state

    @listen(get_user_input)
    def create_guide_outline(self, state):
        """Create a structured outline for the guide using a direct LLM call"""
        print("Creating guide outline...")

        # Initialize the LLM
        llm = LLM(model="openai/gpt-4o-mini", response_format=GuideOutline)

        # Create the messages for the outline
        messages = [
            {"role": "system", "content": "You are a helpful assistant designed to output JSON."},
            {"role": "user", "content": f"""
            Create a detailed outline for a comprehensive guide on "{state.topic}" for {state.audience_level} level learners.

            The outline should include:
            1. A compelling title for the guide
            2. An introduction to the topic
            3. 4-6 main sections that cover the most important aspects of the topic
            4. A conclusion or summary

            For each section, provide a clear title and a brief description of what it should cover.
            """}
        ]

        # Make the LLM call with JSON response format
        response = llm.call(messages=messages)

        # Parse the JSON response
        outline_dict = json.loads(response)
        self.state.guide_outline = GuideOutline(**outline_dict)

        # Ensure output directory exists before saving
        os.makedirs("output", exist_ok=True)

        # Save the outline to a file
        with open("output/guide_outline.json", "w") as f:
            json.dump(outline_dict, f, indent=2)

        print(f"Guide outline created with {len(self.state.guide_outline.sections)} sections")
        return self.state.guide_outline

    @listen(create_guide_outline)
    def write_and_compile_guide(self, outline):
        """Write all sections and compile the guide"""
        print("Writing guide sections and compiling...")
        completed_sections = []

        # Process sections one by one to maintain context flow
        for section in outline.sections:
            print(f"Processing section: {section.title}")

            # Build context from previous sections
            previous_sections_text = ""
            if completed_sections:
                previous_sections_text = "# Previously Written Sections\n\n"
                for title in completed_sections:
                    previous_sections_text += f"## {title}\n\n"
                    previous_sections_text += self.state.sections_content.get(title, "") + "\n\n"
            else:
                previous_sections_text = "No previous sections written yet."

            # Run the content crew for this section
            result = ContentCrew().crew().kickoff(inputs={
                "section_title": section.title,
                "section_description": section.description,
                "audience_level": self.state.audience_level,
                "previous_sections": previous_sections_text,
                "draft_content": ""
            })

            # Store the content
            self.state.sections_content[section.title] = result.raw
            completed_sections.append(section.title)
            print(f"Section completed: {section.title}")

        # Compile the final guide
        guide_content = f"# {outline.title}\n\n"
        guide_content += f"## Introduction\n\n{outline.introduction}\n\n"

        # Add each section in order
        for section in outline.sections:
            section_content = self.state.sections_content.get(section.title, "")
            guide_content += f"\n\n{section_content}\n\n"

        # Add conclusion
        guide_content += f"## Conclusion\n\n{outline.conclusion}\n\n"

        # Save the guide
        with open("output/complete_guide.md", "w") as f:
            f.write(guide_content)

        print("\nComplete guide compiled and saved to output/complete_guide.md")
        return "Guide creation completed successfully"

def kickoff():
    """Run the guide creator flow"""
    GuideCreatorFlow().kickoff()
    print("\n=== Flow Complete ===")
    print("Your comprehensive guide is ready in the output directory.")
    print("Open output/complete_guide.md to view it.")

def plot():
    """Generate a visualization of the flow"""
    flow = GuideCreatorFlow()
    flow.plot("guide_creator_flow")
    print("Flow visualization saved to guide_creator_flow.html")

if __name__ == "__main__":
    kickoff()

crewai install

crewai flow kickoff

crewai flow plot

llm = LLM(
    model="model-id-here",  # gpt-4o, gemini-2.0-flash, anthropic/claude...
    response_format=GuideOutline
)
response = llm.call(messages=messages)

@start()
def get_user_input(self):
    # First step in the flow
    # ...

@listen(get_user_input)
def create_guide_outline(self, state):
    # This runs when get_user_input completes
    # ...

class GuideCreatorState(BaseModel):
    topic: str = ""
    audience_level: str = ""
    guide_outline: GuideOutline = None
    sections_content: Dict[str, str] = {}

result = ContentCrew().crew().kickoff(inputs={
    "section_title": section.title,
    # ...
})