Nestjs 配置跨域中间件

Nestjs 内置了一个 cros 跨域中间件，但只能针对 origin 动态配置，且功能有限，其余都是静态配置，可操作性不强，比如，需要针对「Access-Control-Allow-Headers」根据请求页面的 request-headers 动态追加时，就不能满足了。

第一步，引入 cros 中间件

1// cros.ts
2import { Request, Response, NextFunction } from 'express';
3
4import { PREFLIGHT } from '../constants';
5
6export function cros(request: Request, response: Response, next: NextFunction) {
7  // @ts-ignore
8  const { method, headers, logger, url } = request;
9  const allowHeaders = headers['access-control-request-headers'] || headers['Access-Control-Request-Headers'] || '';
10
11  const cropHeaders = {
12    'Access-Control-Allow-Origin': headers.origin || '*',
13    'Access-Control-Allow-Credentials': true,
14    'Access-Control-Allow-Methods': 'GET, POST, PUT, DELETE, OPTIONS',
15    'Access-Control-Allow-Headers': `swimlane, ${allowHeaders}`,
16    'Access-Control-Max-Age': 600,
17    'Vary': 'Origin',
18  }
19
20  if (method.toLocaleLowerCase() === 'options') {
21    // 记录日志，便于线上定位问题
22    logger.info(PREFLIGHT, {
23      url,
24      result: JSON.stringify(headers)
25    });
26    response.statusCode = 204;
27    response.setHeader('Content-Length', '0');
28    for(var key in cropHeaders) {
29      response.setHeader(key, cropHeaders[key]);
30    }
31    response.end();
32  } else {
33    for(var key in cropHeaders) {
34      response.setHeader(key, cropHeaders[key]);
35    }
36    next();
37  }
38};

第二步，在 app 启动时，注册

1app.use(cros);