Is there any way to get response header back

[shadikkhan]

My microservices are returning the response header but when I integrate that in the graphql mesh gateway I don't see that header. I looked at the doc page to find out if it has to enable anything but couldn't find any solution. Is there any way graphql mesh can return the response header?

I am using the below dependencies with respected versions

    "@graphql-mesh/cli": "0.40.1",
    "@graphql-mesh/config": "0.30.2",
    "@graphql-mesh/graphql": "0.19.0",
    "@graphql-mesh/openapi": "0.18.16",
    "@graphql-mesh/runtime": "0.21.1",
    "@graphql-mesh/transform-filter-schema": "0.11.5",
    "@graphql-mesh/transform-rename": "0.9.15",
    "@graphql-mesh/transform-resolvers-composition": "0.10.16",

[ardatan]

Maybe this helps;
https://the-guild.dev/graphql/mesh/docs/plugins/http-details-extensions

[ardatan]

Yes you should always keep the packages up-to-date :) It is not the latest version returning those extensions but this plugin. Other than that plugin, you can use onFetch hook within a custom plugin you can impleemnt by yourself.

[shinvey]

I did implement a header forward plugin.

// header.plugin.ts

import type { MeshPlugin } from '@graphql-mesh/types'
import type { IncomingMessage, ServerResponse } from 'node:http'

export const filepath = __filename

/**
 * 头信息转发条件判断
 * - 只转发 x- 开头的头信息
 * - 只转发 白名单 中的头信息
 */
function shouldForwardHeader(headerName, whitelist?: Set<string>): boolean {
  if (headerName.startsWith('x-')) {
    return true
  }
  if (whitelist) {
    return whitelist.has(headerName)
  }
  return false
}

function appendHeader(
  headers: Headers | Record<string, string>,
  key: string,
  value: string | string[]
) {
  const _arrValue = Array.isArray(value) ? value : [value]
  _arrValue.forEach(_strValue => {
    if (typeof headers.append === 'function') {
      headers.append(key, _strValue)
    } else {
      headers[key] = _strValue
    }
  })
  return headers
}

/**
 * 请求头信息转发白名单
 *
 * 请慎重选择需要转发的请求头信息，应避免和 /graphql 接口已有的头信息产生冲突，造成无法预知的后果。
 *
 * 默认允许x-开头的请求头信息。后端私有定制的非标准头信息，请在具体的数据源配置文件中内配置。
 * 比如数据源是 httpbin，你可以在 ./src/httpbin/source.ts 中通过以下代码添加自定配置
 *
 * @example
 * requestHeaderWhitelist.add(
 *   // 后端私有定制的非标准头信息。
 *   'client-type'
 * )
 */
export const requestHeaderWhitelist = new Set<string>()

/**
 * 响应头信息转发白名单
 *
 * 请慎重选择需要转发的响应头信息，应避免和 /graphql 接口已有的头信息产生冲突，造成无法预知的后果。
 *
 * @example
 * responseHeaderWhitelist.add(
 *   // 后端私有定制的非标准头信息。
 *   'custom-header'
 * )
 */
export const responseHeaderWhitelist = new Set<string>()

export interface HeaderPluginParams {
  requestHeaders?: string[]
  responseHeaders?: string[]
}

// noinspection JSUnusedGlobalSymbols
export default function headerPlugin({
  requestHeaders = [],
  responseHeaders = [],
}: HeaderPluginParams = {}): MeshPlugin<{
  req: IncomingMessage
  res: ServerResponse
}> {
  requestHeaders.forEach(v => requestHeaderWhitelist.add(v))
  responseHeaders.forEach(v => responseHeaderWhitelist.add(v))
  return {
    async onFetch(onFetchArgs) {
      const { options: fetchRequestInit, context } = onFetchArgs

      // 转发请求头信息
      if (context?.req?.headers) {
        Object.entries(context.req.headers).forEach(([key, value]) => {
          if (shouldForwardHeader(key, requestHeaderWhitelist)) {
            appendHeader(fetchRequestInit.headers, key, value)
          }
        })
      }

      return ({ response }) => {
        // 转发响应头信息
        if (context?.res) {
          response.headers.forEach((value, key) => {
            if (shouldForwardHeader(key, responseHeaderWhitelist)) {
              context.res.appendHeader(key, value)
            }
          })
        }
      }
    },
  }
}

then import this plugin in your meshrc file

// .meshrc.ts

import type { YamlConfig } from '@graphql-mesh/types'
import {
  filepath as responseHeaderPluginFilepath,
  HeaderPluginParams,
} from './src/meshrc/header.plugin'

const meshrcConfig: YamlConfig.Config = {
  // ...
  plugins: [
    {
      [responseHeaderPluginFilepath]: {
        requestHeaders: [
          // 'content-type',
          'referer',
          'user-agent',
          'cookie',
        ],
      } as HeaderPluginParams,
    },
  ],
  // ...
}

export default meshrcConfig

[ardatan]

Seems interesting! But keep in mind that context.req and context.res are only available in Node.js. You can use context.request to access the platform independent Request object; https://developer.mozilla.org/en-US/docs/Web/API/Request/Request

And you can use onResponse hook to access the platform independent Response object.

const respHeadersByRequest = new WeakMap<Request, Headers>();
// ...
      return ({ response }) => {
         let headers = respHeadersByRequest.get(request);
         if (!headers) {
            headers = new Headers();
           respHeadersByRequest.set(request, headers);
         }
         response.headers.forEach((value, key) => {
            if (shouldForwardHeader(key, responseHeaderWhitelist)) {
              headers .append(key, value);
            }
          })
      },
 //...
 onResponse({ response }) {
    const headers = respHeadersByRequest.get(request);
     if (headers) {
        for(const [key, val] of headers) {
           response.headers.append(key, val);
         }
     }
 }

[mlcooper]

@ardatan when I went to the extension that you suggested above it read:

You can expose the details of outgoing HTTP requests

To me this means request headers, but what about response headers? How can I capture a particular response header and expose it as part of the query result?

[ardatan]

Same for response headers