feat: supported langflow api provider (#1646)

* add langflow api provider

* chore: migration

* feat: okay for non-stream req

* fix: langflow sse data extracting

* doc: add comment on langflow api

---------

Co-authored-by: Junyan Qin <rockchinq@gmail.com>

pkg/persistence/migrations/dbm006_langflow_api_config.py

@@ -0,0 +1,45 @@
+from .. import migration
+
+import sqlalchemy
+
+from ...entity.persistence import pipeline as persistence_pipeline
+
+
+@migration.migration_class(6)
+class DBMigrateLangflowApiConfig(migration.DBMigration):
+    """Langflow API config"""
+
+    async def upgrade(self):
+        """Upgrade"""
+        # read all pipelines
+        pipelines = await self.ap.persistence_mgr.execute_async(sqlalchemy.select(persistence_pipeline.LegacyPipeline))
+
+        for pipeline in pipelines:
+            serialized_pipeline = self.ap.persistence_mgr.serialize_model(persistence_pipeline.LegacyPipeline, pipeline)
+
+            config = serialized_pipeline['config']
+
+            if 'langflow-api' not in config['ai']:
+                config['ai']['langflow-api'] = {
+                    'base-url': 'http://localhost:7860',
+                    'api-key': 'your-api-key',
+                    'flow-id': 'your-flow-id',
+                    'input-type': 'chat',
+                    'output-type': 'chat',
+                    'tweaks': '{}',
+                }
+
+            await self.ap.persistence_mgr.execute_async(
+                sqlalchemy.update(persistence_pipeline.LegacyPipeline)
+                .where(persistence_pipeline.LegacyPipeline.uuid == serialized_pipeline['uuid'])
+                .values(
+                    {
+                        'config': config,
+                        'for_version': self.ap.ver_mgr.get_current_version(),
+                    }
+                )
+            )
+
+    async def downgrade(self):
+        """Downgrade"""
+        pass

pkg/provider/runner.py

@@ -35,6 +35,6 @@ class RequestRunner(abc.ABC):
         self.pipeline_config = pipeline_config
 
     @abc.abstractmethod
-    async def run(self, query: core_entities.Query) -> typing.AsyncGenerator[llm_entities.Message, None]:
+    async def run(self, query: core_entities.Query) -> typing.AsyncGenerator[llm_entities.Message | llm_entities.MessageChunk, None]:
         """运行请求"""
         pass

pkg/provider/runners/langflowapi.py

@@ -0,0 +1,180 @@
+from __future__ import annotations
+
+import typing
+import json
+import httpx
+import uuid
+import traceback
+
+from .. import runner
+from ...core import app, entities as core_entities
+from .. import entities as llm_entities
+
+
+@runner.runner_class('langflow-api')
+class LangflowAPIRunner(runner.RequestRunner):
+    """Langflow API 对话请求器"""
+
+    def __init__(self, ap: app.Application, pipeline_config: dict):
+        self.ap = ap
+        self.pipeline_config = pipeline_config
+
+    async def _build_request_payload(self, query: core_entities.Query) -> dict:
+        """构建请求负载
+
+        Args:
+            query: 用户查询对象
+
+        Returns:
+            dict: 请求负载
+        """
+        # 获取用户消息文本
+        user_message_text = ''
+        if isinstance(query.user_message.content, str):
+            user_message_text = query.user_message.content
+        elif isinstance(query.user_message.content, list):
+            for item in query.user_message.content:
+                if item.type == 'text':
+                    user_message_text += item.text
+
+        # 从配置中获取 input_type 和 output_type，如果未配置则使用默认值
+        input_type = self.pipeline_config['ai']['langflow-api'].get('input_type', 'chat')
+        output_type = self.pipeline_config['ai']['langflow-api'].get('output_type', 'chat')
+
+        # 构建基本负载
+        payload = {
+            'output_type': output_type,
+            'input_type': input_type,
+            'input_value': user_message_text,
+            'session_id': str(uuid.uuid4()),
+        }
+
+        # 如果配置中有tweaks，则添加到负载中
+        tweaks = json.loads(self.pipeline_config['ai']['langflow-api'].get('tweaks'))
+        if tweaks:
+            payload['tweaks'] = tweaks
+
+        return payload
+
+    async def run(
+        self, query: core_entities.Query
+    ) -> typing.AsyncGenerator[llm_entities.Message | llm_entities.MessageChunk, None]:
+        """运行请求
+
+        Args:
+            query: 用户查询对象
+
+        Yields:
+            Message: 回复消息
+        """
+        # 检查是否支持流式输出
+        is_stream = False
+        try:
+            is_stream = await query.adapter.is_stream_output_supported()
+        except AttributeError:
+            is_stream = False
+
+        # 从配置中获取API参数
+        base_url = self.pipeline_config['ai']['langflow-api']['base-url']
+        api_key = self.pipeline_config['ai']['langflow-api']['api-key']
+        flow_id = self.pipeline_config['ai']['langflow-api']['flow-id']
+
+        # 构建API URL
+        url = f'{base_url.rstrip("/")}/api/v1/run/{flow_id}'
+
+        # 构建请求负载
+        payload = await self._build_request_payload(query)
+
+        # 设置请求头
+        headers = {'Content-Type': 'application/json', 'x-api-key': api_key}
+
+        # 发送请求
+        async with httpx.AsyncClient() as client:
+            if is_stream:
+                # 流式请求
+                async with client.stream('POST', url, json=payload, headers=headers, timeout=120.0) as response:
+                    print(response)
+                    response.raise_for_status()
+
+                    accumulated_content = ''
+                    message_count = 0
+
+                    async for line in response.aiter_lines():
+                        data_str = line
+
+                        if data_str.startswith('data: '):
+                            data_str = data_str[6:]  # 移除 "data: " 前缀
+
+                        try:
+                            data = json.loads(data_str)
+
+                            # 提取消息内容
+                            message_text = ''
+                            if 'outputs' in data and len(data['outputs']) > 0:
+                                output = data['outputs'][0]
+                                if 'outputs' in output and len(output['outputs']) > 0:
+                                    inner_output = output['outputs'][0]
+                                    if 'outputs' in inner_output and 'message' in inner_output['outputs']:
+                                        message_data = inner_output['outputs']['message']
+                                        if 'message' in message_data:
+                                            message_text = message_data['message']
+
+                            # 如果没有找到消息，尝试其他可能的路径
+                            if not message_text and 'messages' in data:
+                                messages = data['messages']
+                                if messages and len(messages) > 0:
+                                    message_text = messages[0].get('message', '')
+
+                            if message_text:
+                                # 更新累积内容
+                                accumulated_content = message_text
+                                message_count += 1
+
+                                # 每8条消息或有新内容时生成一个chunk
+                                if message_count % 8 == 0 or len(message_text) > 0:
+                                    yield llm_entities.MessageChunk(
+                                        role='assistant', content=accumulated_content, is_final=False
+                                    )
+                        except json.JSONDecodeError:
+                            # 如果不是JSON，跳过这一行
+                            traceback.print_exc()
+                            continue
+
+                    # 发送最终消息
+                    yield llm_entities.MessageChunk(role='assistant', content=accumulated_content, is_final=True)
+            else:
+                # 非流式请求
+                response = await client.post(url, json=payload, headers=headers, timeout=120.0)
+                response.raise_for_status()
+
+                # 解析响应
+                response_data = response.json()
+
+                # 提取消息内容
+                # 根据Langflow API文档，响应结构可能在outputs[0].outputs[0].outputs.message.message中
+                message_text = ''
+                if 'outputs' in response_data and len(response_data['outputs']) > 0:
+                    output = response_data['outputs'][0]
+                    if 'outputs' in output and len(output['outputs']) > 0:
+                        inner_output = output['outputs'][0]
+                        if 'outputs' in inner_output and 'message' in inner_output['outputs']:
+                            message_data = inner_output['outputs']['message']
+                            if 'message' in message_data:
+                                message_text = message_data['message']
+
+                # 如果没有找到消息，尝试其他可能的路径
+                if not message_text and 'messages' in response_data:
+                    messages = response_data['messages']
+                    if messages and len(messages) > 0:
+                        message_text = messages[0].get('message', '')
+
+                # 如果仍然没有找到消息，返回完整响应的字符串表示
+                if not message_text:
+                    message_text = json.dumps(response_data, ensure_ascii=False, indent=2)
+
+                # 生成回复消息
+                if is_stream:
+                    yield llm_entities.MessageChunk(role='assistant', content=message_text, is_final=True)
+                else:
+                    reply_message = llm_entities.Message(role='assistant', content=message_text)
+                    yield reply_message

pkg/utils/constants.py

@@ -1,6 +1,6 @@
 semantic_version = 'v4.2.2'
 
-required_database_version = 5
+required_database_version = 6
 """Tag the version of the database schema, used to check if the database needs to be migrated"""
 
 debug_mode = False

templates/default-pipeline-config.json

@@ -70,6 +70,14 @@
             "header-value": "",
             "timeout": 120,
             "output-key": "response"
+        },
+        "langflow-api": {
+            "base-url": "http://localhost:7860",
+            "api-key": "your-api-key",
+            "flow-id": "your-flow-id",
+            "input-type": "chat",
+            "output-type": "chat",
+            "tweaks": "{}"
         }
     },
     "output": {

templates/metadata/pipeline/ai.yaml

@@ -35,6 +35,10 @@ stages:
             label:
               en_US: n8n Workflow API
               zh_Hans: n8n 工作流 API
+          - name: langflow-api
+            label:
+              en_US: Langflow API
+              zh_Hans: Langflow API
   - name: local-agent
     label:
       en_US: Local Agent
@@ -288,4 +292,68 @@ stages:
         type: string
         required: false
         default: 'response'
-  
+  - name: langflow-api
+    label:
+      en_US: Langflow API
+      zh_Hans: Langflow API
+    description:
+      en_US: Configure the Langflow API of the pipeline, call the Langflow flow through the `Simplified Run Flow` interface
+      zh_Hans: 配置 Langflow API，通过 `Simplified Run Flow` 接口调用 Langflow 的流程
+    config:
+      - name: base-url
+        label:
+          en_US: Base URL
+          zh_Hans: 基础 URL
+        description:
+          en_US: The base URL of the Langflow server
+          zh_Hans: Langflow 服务器的基础 URL
+        type: string
+        required: true
+      - name: api-key
+        label:
+          en_US: API Key
+          zh_Hans: API 密钥
+        description:
+          en_US: The API key for the Langflow server
+          zh_Hans: Langflow 服务器的 API 密钥
+        type: string
+        required: true
+      - name: flow-id
+        label:
+          en_US: Flow ID
+          zh_Hans: 流程 ID
+        description:
+          en_US: The ID of the flow to run
+          zh_Hans: 要运行的流程 ID
+        type: string
+        required: true
+      - name: input-type
+        label:
+          en_US: Input Type
+          zh_Hans: 输入类型
+        description:
+          en_US: The input type for the flow
+          zh_Hans: 流程的输入类型
+        type: string
+        required: false
+        default: 'chat'
+      - name: output-type
+        label:
+          en_US: Output Type
+          zh_Hans: 输出类型
+        description:
+          en_US: The output type for the flow
+          zh_Hans: 流程的输出类型
+        type: string
+        required: false
+        default: 'chat'
+      - name: tweaks
+        label:
+          en_US: Tweaks
+          zh_Hans: 调整参数
+        description:
+          en_US: Optional tweaks to apply to the flow
+          zh_Hans: 可选的流程调整参数
+        type: json
+        required: false
+        default: '{}'