Eino 编排引擎详解：Chain、Graph 与 Workflow 实战

用户输入 → Prompt 组装 → 模型推理 → 工具调用 → 结果解析 → 响应生成

package main

import (
    "context"

    "github.com/cloudwego/eino/compose"
    "github.com/cloudwego/eino/schema"
)

func buildChain(ctx context.Context) {
    // 创建 Chain：输入 map[string]any，输出 *schema.Message
    chain, _ := compose.NewChain[map[string]any, *schema.Message]().
        AppendChatTemplate(prompt).    // 节点1：组装 Prompt
        AppendChatModel(model).        // 节点2：调用模型
        AppendLambda(extractContent).  // 节点3：提取内容
        Compile(ctx)

    // 执行
    result, err := chain.Invoke(ctx, map[string]any{
        "query": "what's your name?",
    })
    if err != nil {
        panic(err)
    }
    fmt.Println(result.Content)
}

func buildAgentGraph(ctx context.Context) {
    graph := compose.NewGraph[map[string]any, *schema.Message]()

    // 添加节点
    _ = graph.AddChatTemplateNode("node_template", chatTpl)
    _ = graph.AddChatModelNode("node_model", chatModel)
    _ = graph.AddToolsNode("node_tools", toolsNode)
    _ = graph.AddLambdaNode("node_converter", takeOne)

    // 定义边
    _ = graph.AddEdge(compose.START, "node_template")
    _ = graph.AddEdge("node_template", "node_model")

    // 条件分支：模型输出是否包含工具调用
    branch := compose.NewBranch(func(ctx context.Context, msg *schema.Message) (string, error) {
        if len(msg.ToolCalls) > 0 {
            return "node_tools", nil
        }
        return compose.END, nil
    })
    _ = graph.AddBranch("node_model", branch)

    // 工具调用后的回路
    _ = graph.AddEdge("node_tools", "node_converter")
    _ = graph.AddEdge("node_converter", "node_model")

    // 编译并执行
    compiledGraph, err := graph.Compile(ctx)
    if err != nil {
        panic(err)
    }

    out, err := compiledGraph.Invoke(ctx, map[string]any{
        "query": "北京这周末天气怎么样",
    })
    fmt.Println(out.Content)
}

func buildWorkflow(ctx context.Context) {
    wf := compose.NewWorkflow[[]*schema.Message, *schema.Message]()

    // 添加节点并定义输入映射
    wf.AddChatModelNode("model", m).AddInput(compose.START)

    wf.AddLambdaNode("lambda1", compose.InvokableLambda(lambda1)).
        AddInput("model", compose.MapFields("Content", "Input"))

    wf.AddLambdaNode("lambda2", compose.InvokableLambda(lambda2)).
        AddInput("model", compose.MapFields("Role", "Role"))

    wf.AddLambdaNode("lambda3", compose.InvokableLambda(lambda3)).
        AddInput("lambda1", compose.MapFields("Output", "Query")).
        AddInput("lambda2", compose.MapFields("Output", "MetaData"))

    wf.End().AddInput("lambda3")

    // 编译并执行
    runnable, err := wf.Compile(ctx)
    if err != nil {
        panic(err)
    }

    result, err := runnable.Invoke(ctx, messages)
    fmt.Println(result.Content)
}

// 编译器会检查 map[string]any → *schema.Message 的类型链路
chain, _ := compose.NewChain[map[string]any, *schema.Message]()

// 为特定节点设置 Option
compiledGraph.Invoke(ctx, input,
    compose.WithNodeOption("node_model", model.WithTemperature(0.7)),
)

package main

import (
    "context"
    "fmt"

    "github.com/cloudwego/eino/compose"
    "github.com/cloudwego/eino/components/model"
    "github.com/cloudwego/eino/components/tool"
    "github.com/cloudwego/eino/schema"
)

// 定义工具：获取天气
func getWeather(ctx context.Context, params map[string]string) (string, error) {
    city := params["city"]
    return fmt.Sprintf("%s 本周末晴，气温 22-28°C", city), nil
}

func main() {
    ctx := context.Background()

    // 初始化组件
    chatModel := initChatModel()       // ChatModel 实例
    chatTpl := initChatTemplate()      // Prompt 模板
    toolsNode := initToolsNode()       // 工具节点
    converter := initConverter()       // 工具结果转换

    // 构建 Graph
    graph := compose.NewGraph[map[string]any, *schema.Message]()

    _ = graph.AddChatTemplateNode("template", chatTpl)
    _ = graph.AddChatModelNode("model", chatModel)
    _ = graph.AddToolsNode("tools", toolsNode)
    _ = graph.AddLambdaNode("converter", converter)

    // 定义执行拓扑
    _ = graph.AddEdge(compose.START, "template")
    _ = graph.AddEdge("template", "model")

    // 条件分支：是否需要调用工具
    branch := compose.NewBranch(func(ctx context.Context, msg *schema.Message) (string, error) {
        if len(msg.ToolCalls) > 0 {
            return "tools", nil
        }
        return compose.END, nil
    })
    _ = graph.AddBranch("model", branch)

    // 工具调用回路
    _ = graph.AddEdge("tools", "converter")
    _ = graph.AddEdge("converter", "model")

    // 编译
    agent, err := graph.Compile(ctx)
    if err != nil {
        panic(fmt.Sprintf("compile error: %v", err))
    }

    // 执行
    result, err := agent.Invoke(ctx, map[string]any{
        "query": "北京这周末天气怎么样？",
    })
    if err != nil {
        panic(err)
    }
    fmt.Println(result.Content)
    // 输出：北京本周末晴，气温 22-28°C，适合户外活动...
}