使用 API Gateway 在 AWS Python Lambda 函数中尝试访问参数时出错

Question

我有这个 python lambda 函数import jsondef lambda_handler(event, context):    post_user = ""    post_user = event["user"]    print(post_user)            return {        "statusCode": 200,        "headers": {"Content-Type": "application/json"},        "body": True        }当我在 lambda IDE 中运行测试时，这按预期工作。测试配置为通过：{“用户”：“约翰”，“密码”：“密码1”}但是当我使用 API Gateway 运行测试时，我收到此错误：Mon Mar 25 20:47:29 UTC 2019：转换前的端点响应主体：{"errorMessage": "'user'", "errorType": "KeyError", "stackTrace": [" File \"/var/task/ lambda_function.py\", line 6, in lambda_handler\n post_user = event[\"user\"]\n"]} Mon Mar 25 20:47:29 UTC 2019：由于客户函数错误，Lambda 执行失败，状态为 200 ：'用户'。Lambda 请求 ID：f7955f74-e608-4b10-b216-4e4acf682307 Mon Mar 25 20:47:29 UTC 2019：方法完成，状态：502我已经定义了 API 网关测试如下：

Answer 1

这是因为当event对象来自 API Gateway 时，它上面有一些额外的信息。它不像您用来从控制台进行测试的 JSON 那样简单。

您需要首先访问该body对象，然后最后访问您的 JSON 对象。

以下是来自 API Gateway 的事件的样子：

{

    "path": "/test/hello",

    "headers": {

      "Accept": "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8",

      "Accept-Encoding": "gzip, deflate, lzma, sdch, br",

      "Accept-Language": "en-US,en;q=0.8",

      "CloudFront-Forwarded-Proto": "https",

      "CloudFront-Is-Desktop-Viewer": "true",

      "CloudFront-Is-Mobile-Viewer": "false",

      "CloudFront-Is-SmartTV-Viewer": "false",

      "CloudFront-Is-Tablet-Viewer": "false",

      "CloudFront-Viewer-Country": "US",

      "Host": "wt6mne2s9k.execute-api.us-west-2.amazonaws.com",

      "Upgrade-Insecure-Requests": "1",

      "User-Agent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/52.0.2743.82 Safari/537.36 OPR/39.0.2256.48",

      "Via": "1.1 fb7cca60f0ecd82ce07790c9c5eef16c.cloudfront.net (CloudFront)",

      "X-Amz-Cf-Id": "nBsWBOrSHMgnaROZJK1wGCZ9PcRcSpq_oSXZNQwQ10OTZL4cimZo3g==",

      "X-Forwarded-For": "192.168.100.1, 192.168.1.1",

      "X-Forwarded-Port": "443",

      "X-Forwarded-Proto": "https"

    },

    "pathParameters": {

      "proxy": "hello"

    },

    "requestContext": {

      "accountId": "123456789012",

      "resourceId": "us4z18",

      "stage": "test",

      "requestId": "41b45ea3-70b5-11e6-b7bd-69b5aaebc7d9",

      "identity": {

        "cognitoIdentityPoolId": "",

        "accountId": "",

        "cognitoIdentityId": "",

        "caller": "",

        "apiKey": "",

        "sourceIp": "192.168.100.1",

        "cognitoAuthenticationType": "",

        "cognitoAuthenticationProvider": "",

        "userArn": "",

        "userAgent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/52.0.2743.82 Safari/537.36 OPR/39.0.2256.48",

        "user": ""

      },

      "resourcePath": "/{proxy+}",

      "httpMethod": "GET",

      "apiId": "wt6mne2s9k"

    },

    "resource": "/{proxy+}",

    "httpMethod": "GET",

    "queryStringParameters": {

      "name": "me"

    },

    "stageVariables": {

      "stageVarName": "stageVarValue"

    },

    "body": "'{\"user\":\"john\",\"pwd\":\"pwd1\"}'"

  }

请记住，body来自 API 网关的始终是字符串化的，因此如果您想访问它，首先需要使用json.loads(event["body"]).

请记住，当返回 API Gateway 时，您的响应正文必须是字符串化的，正如我们在此答案中所讨论的那样。

您可以在文档中看到从 API Gateway 发送的事件

Answer 2

我从回复中得到的关键与他的建议不同，但他的建议对我有帮助，所以我接受它作为答案

我得到了这个回应。该body键来为null。但有queryStringParameters

{

  "resource": "/match_creds",

  "path": "/match_creds",

  "httpMethod": "GET",

  "headers": null,

  "multiValueHeaders": null,

  "queryStringParameters": {

    "pwd": "pwd1",

    "user": "JOHN"

  },

  "multiValueQueryStringParameters": {

    "pwd": [

      "pwd1"

    ],

    "user": [

      "JOHN"

    ]

  },

  "pathParameters": null,

  "stageVariables": null,

  "requestContext": {

    "path": "/match_creds",

    "accountId": "",

    "resourceId": "",

    "stage": "test-invoke-stage",

    "domainPrefix": "testPrefix",

    "requestId": "",

    "identity": {

      "cognitoIdentityPoolId": null,

      "cognitoIdentityId": null,

      "apiKey": "test-invoke-api-key",

      "cognitoAuthenticationType": null,

      "userArn": "",

      "apiKeyId": "test-invoke-api-key-id",

      "userAgent": "",

      "accountId": "",

      "caller": "",

      "sourceIp": "test-invoke-source-ip",

      "accessKey": "",

      "cognitoAuthenticationProvider": null,

      "user": ""

    },

    "domainName": "testPrefix.testDomainName",

    "resourcePath": "/match_creds",

    "httpMethod": "GET",

    "extendedRequestId": "",

    "apiId": ""

  },

  "body": null,

  "isBase64Encoded": false

}

我改变了我的功能

import json

    def lambda_handler(event, context):

        json_data = event["queryStringParameters"] 

        user = json_data["user"]

        return {

            "statusCode": 200,

            "headers": {"Content-Type": "application/json"},

            "body": json.dumps(user)

            }