Contact Form Text Classifier for eCommerce
工作流概述
这是一个包含14个节点的复杂工作流，主要用于自动化处理各种任务。
工作流源代码
{
"id": "LGpVLWPpNZSt9ISM",
"meta": {
"instanceId": "a4bfc93e975ca233ac45ed7c9227d84cf5a2329310525917adaf3312e10d5462",
"templateCredsSetupCompleted": true
},
"name": "Contact Form Text Classifier for eCommerce",
"tags": [],
"nodes": [
{
"id": "13175d48-c3a6-4ca6-afed-b70f40289f38",
"name": "On form submission",
"type": "n8n-nodes-base.formTrigger",
"position": [
-480,
-320
],
"webhookId": "8e10c8ca-895c-4274-ba95-0d646b8bda4e",
"parameters": {
"options": {},
"formTitle": "Contacts",
"formFields": {
"values": [
{
"fieldLabel": "Name",
"placeholder": "Name",
"requiredField": true
},
{
"fieldLabel": "Email",
"placeholder": "Email",
"requiredField": true
},
{
"fieldType": "textarea",
"fieldLabel": "Message",
"placeholder": "Message",
"requiredField": true
}
]
},
"responseMode": "lastNode",
"formDescription": "Basic Contact Form"
},
"typeVersion": 2.2
},
{
"id": "7b352c9f-5d2e-46ca-9499-594063167e9a",
"name": "Text Classifier",
"type": "@n8n/n8n-nodes-langchain.textClassifier",
"position": [
-160,
-320
],
"parameters": {
"options": {
"fallback": "other",
"systemPromptTemplate": "=Please classify the text provided by the user into one of the following categories: {categories}, and use the provided formatting instructions below. Don't explain, and only output the json with the selected {categories}."
},
"inputText": "={{ $json.Message }}",
"categories": {
"categories": [
{
"category": "Request Quote",
"description": "Request for quote"
},
{
"category": "Product info",
"description": "General information about a product"
},
{
"category": "General problem",
"description": "General problems about a product"
},
{
"category": "Order",
"description": "Information about an order placed"
}
]
}
},
"typeVersion": 1
},
{
"id": "efef4c71-5f56-44b0-a613-9fa888e495b8",
"name": "OpenAI",
"type": "@n8n/n8n-nodes-langchain.lmChatOpenAi",
"position": [
-220,
-100
],
"parameters": {
"model": {
"__rl": true,
"mode": "list",
"value": "gpt-4o-mini",
"cachedResultName": "gpt-4o-mini"
},
"options": {}
},
"credentials": {
"openAiApi": {
"id": "CDX6QM4gLYanh0P4",
"name": "OpenAi account"
}
},
"typeVersion": 1.2
},
{
"id": "83f0d528-884c-4701-8fdd-dc07c05fafb5",
"name": "Prod. Dep.",
"type": "n8n-nodes-base.emailSend",
"position": [
320,
-540
],
"parameters": {
"html": "=Name: {{ $json.Name }}
Email: {{ $json.Email }}
Message:
{{ $json.Message }}
Tipo prodotto: {{ $json[\"tipo prodotto\"] }}",
"options": {
"replyTo": "={{ $json.Email }}"
},
"subject": "=[n8n Contacts] Product info",
"toEmail": "to@domain.com",
"fromEmail": "from@domain.com"
},
"credentials": {
"smtp": {
"id": "hRjP3XbDiIQqvi7x",
"name": "SMTP info@n3witalia.com"
}
},
"typeVersion": 2.1
},
{
"id": "88486500-dcea-4db9-9ffd-f55193eaa83d",
"name": "Quote Dep.",
"type": "n8n-nodes-base.emailSend",
"position": [
320,
-780
],
"parameters": {
"html": "=Name: {{ $json.Name }}
Email: {{ $json.Email }}
Message:
{{ $json.Message }}
Tipo prodotto: {{ $json[\"tipo prodotto\"] }}",
"options": {
"replyTo": "={{ $json.Email }}"
},
"subject": "=[n8n Contacts] Quote",
"toEmail": "to@domain.com",
"fromEmail": "from@domain.com"
},
"credentials": {
"smtp": {
"id": "hRjP3XbDiIQqvi7x",
"name": "SMTP info@n3witalia.com"
}
},
"typeVersion": 2.1
},
{
"id": "f6a63c4f-ee2e-42f1-a12c-b1fc6cf48f94",
"name": "Gen. Dep.",
"type": "n8n-nodes-base.emailSend",
"position": [
320,
-320
],
"parameters": {
"html": "=Name: {{ $json.Name }}
Email: {{ $json.Email }}
Message:
{{ $json.Message }}
Tipo prodotto: {{ $json[\"tipo prodotto\"] }}",
"options": {
"replyTo": "={{ $json.Email }}"
},
"subject": "=[n8n Contacts] General",
"toEmail": "to@domain.com",
"fromEmail": "from@domain.com"
},
"credentials": {
"smtp": {
"id": "hRjP3XbDiIQqvi7x",
"name": "SMTP info@n3witalia.com"
}
},
"typeVersion": 2.1
},
{
"id": "04a3e144-af75-4a95-819f-d5f1d4591b67",
"name": "Order Dep.",
"type": "n8n-nodes-base.emailSend",
"position": [
320,
-80
],
"parameters": {
"html": "=Name: {{ $json.Name }}
Email: {{ $json.Email }}
Message:
{{ $json.Message }}
Tipo prodotto: {{ $json[\"tipo prodotto\"] }}",
"options": {
"replyTo": "={{ $json.Email }}"
},
"subject": "=[n8n Contacts] Order info",
"toEmail": "to@domain.com",
"fromEmail": "from@domain.com"
},
"credentials": {
"smtp": {
"id": "hRjP3XbDiIQqvi7x",
"name": "SMTP info@n3witalia.com"
}
},
"typeVersion": 2.1
},
{
"id": "3767e3c7-b792-4b0d-a1f2-fc068310cb11",
"name": "Other Dep.",
"type": "n8n-nodes-base.emailSend",
"position": [
320,
140
],
"parameters": {
"html": "=Name: {{ $json.Name }}
Email: {{ $json.Email }}
Message:
{{ $json.Message }}
Tipo prodotto: {{ $json[\"tipo prodotto\"] }}",
"options": {
"replyTo": "={{ $json.Email }}"
},
"subject": "=[n8n Contacts] Other",
"toEmail": "to@domain.com",
"fromEmail": "from@domain.com"
},
"credentials": {
"smtp": {
"id": "hRjP3XbDiIQqvi7x",
"name": "SMTP info@n3witalia.com"
}
},
"typeVersion": 2.1
},
{
"id": "c411a82d-0b86-49da-a11f-47ec79f9f7ff",
"name": "Quote DB",
"type": "n8n-nodes-base.googleSheets",
"position": [
520,
-780
],
"parameters": {
"columns": {
"value": {
"TO": "={{ (JSON.stringify($json.envelope.to)) }}",
"DATA": "={{ $('Text Classifier').item.json.submittedAt }}",
"NOME": "={{ $('Text Classifier').item.json.Name }}",
"EMAIL": "={{ $('Text Classifier').item.json.Email }}",
"CATEGORIA": "info prodotti",
"RICHIESTA": "={{ $('Text Classifier').item.json.Message }}"
},
"schema": [
{
"id": "DATA",
"type": "string",
"display": true,
"required": false,
"displayName": "DATA",
"defaultMatch": false,
"canBeUsedToMatch": true
},
{
"id": "NOME",
"type": "string",
"display": true,
"required": false,
"displayName": "NOME",
"defaultMatch": false,
"canBeUsedToMatch": true
},
{
"id": "EMAIL",
"type": "string",
"display": true,
"required": false,
"displayName": "EMAIL",
"defaultMatch": false,
"canBeUsedToMatch": true
},
{
"id": "RICHIESTA",
"type": "string",
"display": true,
"required": false,
"displayName": "RICHIESTA",
"defaultMatch": false,
"canBeUsedToMatch": true
},
{
"id": "CATEGORIA",
"type": "string",
"display": true,
"required": false,
"displayName": "CATEGORIA",
"defaultMatch": false,
"canBeUsedToMatch": true
},
{
"id": "TO",
"type": "string",
"display": true,
"removed": false,
"required": false,
"displayName": "TO",
"defaultMatch": false,
"canBeUsedToMatch": true
}
],
"mappingMode": "defineBelow",
"matchingColumns": [],
"attemptToConvertTypes": false,
"convertFieldsToString": false
},
"options": {},
"operation": "append",
"sheetName": {
"__rl": true,
"mode": "list",
"value": "gid=0",
"cachedResultUrl": "https://docs.google.com/spreadsheets/d/1D6tfsAK81ZE6VA0-sd_syuyI_rloNYjgWOhwgszPIZw/edit#gid=0",
"cachedResultName": "Foglio1"
},
"documentId": {
"__rl": true,
"mode": "list",
"value": "1D6tfsAK81ZE6VA0-sd_syuyI_rloNYjgWOhwgszPIZw",
"cachedResultUrl": "https://docs.google.com/spreadsheets/d/1D6tfsAK81ZE6VA0-sd_syuyI_rloNYjgWOhwgszPIZw/edit?usp=drivesdk",
"cachedResultName": "Classified Contact Form"
}
},
"credentials": {
"googleSheetsOAuth2Api": {
"id": "JYR6a64Qecd6t8Hb",
"name": "Google Sheets account"
}
},
"typeVersion": 4.5
},
{
"id": "c14008fb-8932-44ad-88ef-42f6d4029fb1",
"name": "Prod DB",
"type": "n8n-nodes-base.googleSheets",
"position": [
520,
-540
],
"parameters": {
"columns": {
"value": {
"TO": "={{ (JSON.stringify($json.envelope.to)) }}",
"DATA": "={{ $('Text Classifier').item.json.submittedAt }}",
"NOME": "={{ $('Text Classifier').item.json.Name }}",
"EMAIL": "={{ $('Text Classifier').item.json.Email }}",
"CATEGORIA": "info prodotti",
"RICHIESTA": "={{ $('Text Classifier').item.json.Message }}"
},
"schema": [
{
"id": "DATA",
"type": "string",
"display": true,
"required": false,
"displayName": "DATA",
"defaultMatch": false,
"canBeUsedToMatch": true
},
{
"id": "NOME",
"type": "string",
"display": true,
"required": false,
"displayName": "NOME",
"defaultMatch": false,
"canBeUsedToMatch": true
},
{
"id": "EMAIL",
"type": "string",
"display": true,
"required": false,
"displayName": "EMAIL",
"defaultMatch": false,
"canBeUsedToMatch": true
},
{
"id": "RICHIESTA",
"type": "string",
"display": true,
"required": false,
"displayName": "RICHIESTA",
"defaultMatch": false,
"canBeUsedToMatch": true
},
{
"id": "CATEGORIA",
"type": "string",
"display": true,
"required": false,
"displayName": "CATEGORIA",
"defaultMatch": false,
"canBeUsedToMatch": true
},
{
"id": "TO",
"type": "string",
"display": true,
"removed": false,
"required": false,
"displayName": "TO",
"defaultMatch": false,
"canBeUsedToMatch": true
}
],
"mappingMode": "defineBelow",
"matchingColumns": [],
"attemptToConvertTypes": false,
"convertFieldsToString": false
},
"options": {},
"operation": "append",
"sheetName": {
"__rl": true,
"mode": "list",
"value": "gid=0",
"cachedResultUrl": "https://docs.google.com/spreadsheets/d/1D6tfsAK81ZE6VA0-sd_syuyI_rloNYjgWOhwgszPIZw/edit#gid=0",
"cachedResultName": "Foglio1"
},
"documentId": {
"__rl": true,
"mode": "list",
"value": "1D6tfsAK81ZE6VA0-sd_syuyI_rloNYjgWOhwgszPIZw",
"cachedResultUrl": "https://docs.google.com/spreadsheets/d/1D6tfsAK81ZE6VA0-sd_syuyI_rloNYjgWOhwgszPIZw/edit?usp=drivesdk",
"cachedResultName": "Classified Contact Form"
}
},
"credentials": {
"googleSheetsOAuth2Api": {
"id": "JYR6a64Qecd6t8Hb",
"name": "Google Sheets account"
}
},
"typeVersion": 4.5
},
{
"id": "f2e02c07-7218-4d08-a816-1ce2de289312",
"name": "General DB",
"type": "n8n-nodes-base.googleSheets",
"position": [
520,
-320
],
"parameters": {
"columns": {
"value": {
"TO": "={{ (JSON.stringify($json.envelope.to)) }}",
"DATA": "={{ $('Text Classifier').item.json.submittedAt }}",
"NOME": "={{ $('Text Classifier').item.json.Name }}",
"EMAIL": "={{ $('Text Classifier').item.json.Email }}",
"CATEGORIA": "info prodotti",
"RICHIESTA": "={{ $('Text Classifier').item.json.Message }}"
},
"schema": [
{
"id": "DATA",
"type": "string",
"display": true,
"required": false,
"displayName": "DATA",
"defaultMatch": false,
"canBeUsedToMatch": true
},
{
"id": "NOME",
"type": "string",
"display": true,
"required": false,
"displayName": "NOME",
"defaultMatch": false,
"canBeUsedToMatch": true
},
{
"id": "EMAIL",
"type": "string",
"display": true,
"required": false,
"displayName": "EMAIL",
"defaultMatch": false,
"canBeUsedToMatch": true
},
{
"id": "RICHIESTA",
"type": "string",
"display": true,
"required": false,
"displayName": "RICHIESTA",
"defaultMatch": false,
"canBeUsedToMatch": true
},
{
"id": "CATEGORIA",
"type": "string",
"display": true,
"required": false,
"displayName": "CATEGORIA",
"defaultMatch": false,
"canBeUsedToMatch": true
},
{
"id": "TO",
"type": "string",
"display": true,
"removed": false,
"required": false,
"displayName": "TO",
"defaultMatch": false,
"canBeUsedToMatch": true
}
],
"mappingMode": "defineBelow",
"matchingColumns": [],
"attemptToConvertTypes": false,
"convertFieldsToString": false
},
"options": {},
"operation": "append",
"sheetName": {
"__rl": true,
"mode": "list",
"value": "gid=0",
"cachedResultUrl": "https://docs.google.com/spreadsheets/d/1D6tfsAK81ZE6VA0-sd_syuyI_rloNYjgWOhwgszPIZw/edit#gid=0",
"cachedResultName": "Foglio1"
},
"documentId": {
"__rl": true,
"mode": "list",
"value": "1D6tfsAK81ZE6VA0-sd_syuyI_rloNYjgWOhwgszPIZw",
"cachedResultUrl": "https://docs.google.com/spreadsheets/d/1D6tfsAK81ZE6VA0-sd_syuyI_rloNYjgWOhwgszPIZw/edit?usp=drivesdk",
"cachedResultName": "Classified Contact Form"
}
},
"credentials": {
"googleSheetsOAuth2Api": {
"id": "JYR6a64Qecd6t8Hb",
"name": "Google Sheets account"
}
},
"typeVersion": 4.5
},
{
"id": "d6ee5c05-d966-47c1-a7ec-df721f77c5d0",
"name": "Order DB",
"type": "n8n-nodes-base.googleSheets",
"position": [
520,
-80
],
"parameters": {
"columns": {
"value": {
"TO": "={{ (JSON.stringify($json.envelope.to)) }}",
"DATA": "={{ $('Text Classifier').item.json.submittedAt }}",
"NOME": "={{ $('Text Classifier').item.json.Name }}",
"EMAIL": "={{ $('Text Classifier').item.json.Email }}",
"CATEGORIA": "info prodotti",
"RICHIESTA": "={{ $('Text Classifier').item.json.Message }}"
},
"schema": [
{
"id": "DATA",
"type": "string",
"display": true,
"required": false,
"displayName": "DATA",
"defaultMatch": false,
"canBeUsedToMatch": true
},
{
"id": "NOME",
"type": "string",
"display": true,
"required": false,
"displayName": "NOME",
"defaultMatch": false,
"canBeUsedToMatch": true
},
{
"id": "EMAIL",
"type": "string",
"display": true,
"required": false,
"displayName": "EMAIL",
"defaultMatch": false,
"canBeUsedToMatch": true
},
{
"id": "RICHIESTA",
"type": "string",
"display": true,
"required": false,
"displayName": "RICHIESTA",
"defaultMatch": false,
"canBeUsedToMatch": true
},
{
"id": "CATEGORIA",
"type": "string",
"display": true,
"required": false,
"displayName": "CATEGORIA",
"defaultMatch": false,
"canBeUsedToMatch": true
},
{
"id": "TO",
"type": "string",
"display": true,
"removed": false,
"required": false,
"displayName": "TO",
"defaultMatch": false,
"canBeUsedToMatch": true
}
],
"mappingMode": "defineBelow",
"matchingColumns": [],
"attemptToConvertTypes": false,
"convertFieldsToString": false
},
"options": {},
"operation": "append",
"sheetName": {
"__rl": true,
"mode": "list",
"value": "gid=0",
"cachedResultUrl": "https://docs.google.com/spreadsheets/d/1D6tfsAK81ZE6VA0-sd_syuyI_rloNYjgWOhwgszPIZw/edit#gid=0",
"cachedResultName": "Foglio1"
},
"documentId": {
"__rl": true,
"mode": "list",
"value": "1D6tfsAK81ZE6VA0-sd_syuyI_rloNYjgWOhwgszPIZw",
"cachedResultUrl": "https://docs.google.com/spreadsheets/d/1D6tfsAK81ZE6VA0-sd_syuyI_rloNYjgWOhwgszPIZw/edit?usp=drivesdk",
"cachedResultName": "Classified Contact Form"
}
},
"credentials": {
"googleSheetsOAuth2Api": {
"id": "JYR6a64Qecd6t8Hb",
"name": "Google Sheets account"
}
},
"typeVersion": 4.5
},
{
"id": "b4f344bd-a5c4-4977-af96-edbab85b49d0",
"name": "Other DB",
"type": "n8n-nodes-base.googleSheets",
"position": [
520,
140
],
"parameters": {
"columns": {
"value": {
"TO": "={{ (JSON.stringify($json.envelope.to)) }}",
"DATA": "={{ $('Text Classifier').item.json.submittedAt }}",
"NOME": "={{ $('Text Classifier').item.json.Name }}",
"EMAIL": "={{ $('Text Classifier').item.json.Email }}",
"CATEGORIA": "info prodotti",
"RICHIESTA": "={{ $('Text Classifier').item.json.Message }}"
},
"schema": [
{
"id": "DATA",
"type": "string",
"display": true,
"required": false,
"displayName": "DATA",
"defaultMatch": false,
"canBeUsedToMatch": true
},
{
"id": "NOME",
"type": "string",
"display": true,
"required": false,
"displayName": "NOME",
"defaultMatch": false,
"canBeUsedToMatch": true
},
{
"id": "EMAIL",
"type": "string",
"display": true,
"required": false,
"displayName": "EMAIL",
"defaultMatch": false,
"canBeUsedToMatch": true
},
{
"id": "RICHIESTA",
"type": "string",
"display": true,
"required": false,
"displayName": "RICHIESTA",
"defaultMatch": false,
"canBeUsedToMatch": true
},
{
"id": "CATEGORIA",
"type": "string",
"display": true,
"required": false,
"displayName": "CATEGORIA",
"defaultMatch": false,
"canBeUsedToMatch": true
},
{
"id": "TO",
"type": "string",
"display": true,
"removed": false,
"required": false,
"displayName": "TO",
"defaultMatch": false,
"canBeUsedToMatch": true
}
],
"mappingMode": "defineBelow",
"matchingColumns": [],
"attemptToConvertTypes": false,
"convertFieldsToString": false
},
"options": {},
"operation": "append",
"sheetName": {
"__rl": true,
"mode": "list",
"value": "gid=0",
"cachedResultUrl": "https://docs.google.com/spreadsheets/d/1D6tfsAK81ZE6VA0-sd_syuyI_rloNYjgWOhwgszPIZw/edit#gid=0",
"cachedResultName": "Foglio1"
},
"documentId": {
"__rl": true,
"mode": "list",
"value": "1D6tfsAK81ZE6VA0-sd_syuyI_rloNYjgWOhwgszPIZw",
"cachedResultUrl": "https://docs.google.com/spreadsheets/d/1D6tfsAK81ZE6VA0-sd_syuyI_rloNYjgWOhwgszPIZw/edit?usp=drivesdk",
"cachedResultName": "Classified Contact Form"
}
},
"credentials": {
"googleSheetsOAuth2Api": {
"id": "JYR6a64Qecd6t8Hb",
"name": "Google Sheets account"
}
},
"typeVersion": 4.5
},
{
"id": "99872f49-85c3-47a0-b0ea-10ebbdbb67f5",
"name": "Sticky Note",
"type": "n8n-nodes-base.stickyNote",
"position": [
-480,
-680
],
"parameters": {
"width": 580,
"height": 280,
"content": "## Important notes
This very simple workflow is ideal for eCommerce businesses or customer support teams looking to automate and streamline the handling of contact form submissions.
- It is possible to hook any external form such as CF7 for Wordpress through a webhook
- It is possible to send the email through other providers by replacing them with the relative nodes (Gmail, Outlook....)
- It is possible to change the collection database with other tools"
},
"typeVersion": 1
}
],
"active": false,
"pinData": {},
"settings": {
"executionOrder": "v1"
},
"versionId": "649d6a6a-a2a1-49f6-b63a-6def1a8831f1",
"connections": {
"OpenAI": {
"ai_languageModel": [
[
{
"node": "Text Classifier",
"type": "ai_languageModel",
"index": 0
}
]
]
},
"Gen. Dep.": {
"main": [
[
{
"node": "General DB",
"type": "main",
"index": 0
}
]
]
},
"Order Dep.": {
"main": [
[
{
"node": "Order DB",
"type": "main",
"index": 0
}
]
]
},
"Other Dep.": {
"main": [
[
{
"node": "Other DB",
"type": "main",
"index": 0
}
]
]
},
"Prod. Dep.": {
"main": [
[
{
"node": "Prod DB",
"type": "main",
"index": 0
}
]
]
},
"Quote Dep.": {
"main": [
[
{
"node": "Quote DB",
"type": "main",
"index": 0
}
]
]
},
"Text Classifier": {
"main": [
[
{
"node": "Quote Dep.",
"type": "main",
"index": 0
},
{
"node": "Prod. Dep.",
"type": "main",
"index": 0
}
],
[],
[
{
"node": "Gen. Dep.",
"type": "main",
"index": 0
}
],
[
{
"node": "Order Dep.",
"type": "main",
"index": 0
}
],
[
{
"node": "Other Dep.",
"type": "main",
"index": 0
}
]
]
},
"On form submission": {
"main": [
[
{
"node": "Text Classifier",
"type": "main",
"index": 0
}
]
]
}
}
}功能特点
- 自动检测新邮件
- AI智能内容分析
- 自定义分类规则
- 批量处理能力
- 详细的处理日志
技术分析
节点类型及作用
- Formtrigger
- @N8N/N8N Nodes Langchain.Textclassifier
- @N8N/N8N Nodes Langchain.Lmchatopenai
- Emailsend
- Googlesheets
复杂度评估
配置难度：
维护难度：
扩展性：
实施指南
前置条件
- 有效的Gmail账户
- n8n平台访问权限
- Google API凭证
- AI分类服务订阅
配置步骤
- 在n8n中导入工作流JSON文件
- 配置Gmail节点的认证信息
- 设置AI分类器的API密钥
- 自定义分类规则和标签映射
- 测试工作流执行
- 配置定时触发器（可选）
关键参数
| 参数名称 | 默认值 | 说明 |
|---|---|---|
| maxEmails | 50 | 单次处理的最大邮件数量 |
| confidenceThreshold | 0.8 | 分类置信度阈值 |
| autoLabel | true | 是否自动添加标签 |
最佳实践
优化建议
- 定期更新AI分类模型以提高准确性
- 根据邮件量调整处理批次大小
- 设置合理的分类置信度阈值
- 定期清理过期的分类规则
安全注意事项
- 妥善保管API密钥和认证信息
- 限制工作流的访问权限
- 定期审查处理日志
- 启用双因素认证保护Gmail账户
性能优化
- 使用增量处理减少重复工作
- 缓存频繁访问的数据
- 并行处理多个邮件分类任务
- 监控系统资源使用情况
故障排除
常见问题
邮件未被正确分类
检查AI分类器的置信度阈值设置，适当降低阈值或更新训练数据。
Gmail认证失败
确认Google API凭证有效且具有正确的权限范围，重新进行OAuth授权。
调试技巧
- 启用详细日志记录查看每个步骤的执行情况
- 使用测试邮件验证分类逻辑
- 检查网络连接和API服务状态
- 逐步执行工作流定位问题节点
错误处理
工作流包含以下错误处理机制：
- 网络超时自动重试（最多3次）
- API错误记录和告警
- 处理失败邮件的隔离机制
- 异常情况下的回滚操作