无服务器框架+ AWS + Lambda + DynamoDB + GraphQL + Apollo Server =无法使POST请求工作

Question

好的，我几天就遇到了这个问题。

我尝试学习本教程：https://serverless.com/blog/make-serverless-graphql-api-using-lambda-dynamodb/

并使其与apollo-server-lambda一起使用。本教程帮助：

https://medium.com/vessels/apollo-server-serverless-graphql-bliss-68e8e15195ac

问题是，当您尝试将apollo server lambda与DynamoDB实际连接时，没有任何工作（对我而言）。我得到了一个我不记得的错误列表，这只是令人沮丧。

这是我的代码：

# serverless.yml
service: graphql-api

provider:
  name: aws
  runtime: nodejs6.10
  region: eu-west-3
  stage: dev
  environment:
    DYNAMODB_TABLE: ${self:service}-${self:provider.stage}
  iamRoleStatements:
    - Effect: Allow
      Action:
        - dynamodb:GetItem
        - dynamodb:UpdateItem
      Resource: "arn:aws:dynamodb:${opt:region, self:provider.region}:*:table/${self:provider.environment.DYNAMODB_TABLE}"

resources:
  Resources:
    NicknamesTable:
      Type: 'AWS::DynamoDB::Table'
      Properties:
        AttributeDefinitions:
          - AttributeName: firstName
            AttributeType: S
        KeySchema:
          - AttributeName: firstName
            KeyType: HASH
        ProvisionedThroughput:
          ReadCapacityUnits: 1
          WriteCapacityUnits: 1
        TableName: ${self:provider.environment.DYNAMODB_TABLE}

functions:
  graphql:
    handler: handler.graphql
    events:
      - http:
          path: graphql
          method: post
          cors: true
      - http:
          path: graphql
          method: get
          cors: true

我的经纪人：

# handler.js
const AWS = require('aws-sdk');
const server = require("apollo-server-lambda");
const makeExecutableSchema = require('graphql-tools').makeExecutableSchema;
const dynamoDb = new AWS.DynamoDB.DocumentClient();

const promisify = foo => new Promise((resolve, reject) => {
    foo((error, result) => {
        if (error) {
            reject(error)
        } else {
            resolve(result)
        }
    })
})

const getGreeting = firstName => promisify(callback =>
    dynamoDb.get({
        TableName: process.env.DYNAMODB_TABLE,
        Key: { firstName },
    }, callback))
    .then(result => {
        if (!result.Item) {
            return firstName
        }
        return result.Item.nickname
    })
    .then(name => `Hello, ${name}.`)

// add method for updates
const changeNickname = (firstName, nickname) => promisify(callback =>
    dynamoDb.update({
        TableName: process.env.DYNAMODB_TABLE,
        Key: { firstName },
        UpdateExpression: 'SET nickname = :nickname',
        ExpressionAttributeValues: {
            ':nickname': nickname
        }
    }, callback))
    .then(() => nickname)

const typeDefs = `
    type Query {
        greeting(firstName: String!): String
    }
    type Mutation {
        changeNickname(
            firstName: String!
            nickname: String!
        ): String
    }
`;

const resolvers = {
    Query: {
        greeting: (_, { firstName }) => getGreeting(firstName),
    },
    Mutation: {
        changeNickname: (_, { firstName, nickname }) => changeNickname(firstName, nickname),
    }
};

exports.graphql = function (event, context, callback) {
    const callbackFilter = function (error, output) {
        output.headers = output.header || {};
        output.headers['Access-Control-Allow-Origin'] = '*';
        callback(error, output);
    };
    const handler = server.graphqlLambda({ schema: makeExecutableSchema({ typeDefs, resolvers }) });

    return handler(event, context, callbackFilter);
};

我尝试使用Apollo 1和2，没什么用。我回到版本1，因为有更多关于它的论坛帖子。大多数情况下，我有“内部服务器错误”。我尝试了在apollo docs上找到的不同版本的服务器，但我的所有请求都失败了，在终端上使用curl或直接在AWS上的API网关上测试该功能。我按照以下文档编写了请求正文：https://www.apollographql.com/docs/apollo-server/requests.html

这是我的cloudwatch日志：

(node:1) UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 1): SyntaxError: Unexpected token = in JSON at position 8

任何帮助将非常感谢!!

Answer 1

好的，我发现了问题。当您使用put函数时，您无法获得刚刚在dynamoDB中插入的新项目。你必须在你的params对象（put函数的第一个参数）中放入“ReturnValues：'ALL_OLD'”，就像没有抛出错误一样，你应该返回你想要的值，因为你刚刚在db中输入了它们。

更多细节在这里：

https://github.com/aws/aws-sdk-js/issues/803