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唯一键

简介​

校验请求参数映射的一列或一组列中的值是唯一的。

示例​

假设有人力资源系统部门表，表结构如下

CREATE TABLE `departments` (
  `dept_no` char(4) NOT NULL,
  `dept_name` varchar(40) NOT NULL,
  PRIMARY KEY (`dept_no`),
  UNIQUE KEY `dept_name` (`dept_name`)
)

检查规则约束​

  • 部门编号作为主键字段，具备唯一性，主键更多详见主键
  • 部门名称dept_name作为唯一键，具有唯一性

示例1：成功请求​

新增一条部门名称在数据表中不存在的记录

POST http://127.0.0.1:21000
Content-Type: application/json;charset=utf-8
{
  "jsonrpc": "2.0",
  "method": "hrm.departments.add",
  "params": {
    "deptNo": "d234",
    "deptName": "Human Resources"
  },
  "id": "client-unique-request-id"
}

响应​

以上请求响应结果，插入成功返回对象包含主键名和值

HTTP/1.1 200 OK
Content-Type: application/json; charset=utf-8
{
  "jsonrpc": "2.0",
  "result": {
    "deptNo": "d234"
  },
  "id": "client-unique-request-id"
}

示例2：失败请求--部门名称已经存在​

现在我们尝试新增一条同名的部门记录

POST http://127.0.0.1:21000
Content-Type: application/json;charset=utf-8
{
  "jsonrpc": "2.0",
  "method": "hrm.departments.add",
  "params": {
    "deptNo": "d235",
    "deptName": "Human Resources"
  },
  "id": "client-unique-request-id"
}

响应结果​

HTTP/1.1 400 Bad Request
Content-Type: application/json; charset=utf-8
{
  "jsonrpc": "2.0",
  "error": {
    "code": -32600,
    "message": "checking for unique key conflicts: duplicate unique key in hrm.departments map[deptName:Human Resources]",
    "data": {
      "errorCode": "EU.Constraint.UK.Duplicated",
      "errorDetails": [
        {
          "constraint": "UniqueKeyDuplicated",
          "field": "deptName",
          "fieldValue": "Human Resources",
          "location": "hrm.departments",
          "message": "duplicate unique key in hrm.departments.dept_name Human Resources"
        }
      ],
      "errorMessage": "duplicate unique key in hrm.departments map[deptName:Human Resources]"
    }
  },
  "id": "client-unique-request-id"
}

可见dept_name存在重复了，唯一键约束校验失败，该请求被拦截，Luwak拒绝写入。

以上示例 Tested on Luwak 1.12.9

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