从 dynamoDB getItem 导出值

Question

我正在尝试从 dynamoDB 获取 getItem 函数之外的数据，但出现此错误，我不知道为什么。

Error ValidationException: Supplied AttributeValue is empty, must contain exactly one of the supported datatypes

这是我的代码

const aws = require("aws-sdk"),
  docClient = new aws.DynamoDB.DocumentClient({ apiVersion: "2012-08-10" }),
  ddb = new aws.DynamoDB({ apiVersion: "2012-08-10" }),
  tableName = "usersDB",

 exports.apiKey = async (req, res, context) => {
  var params = {
    TableName: tableName,
    Key: {
      "username": { "S": req.body.username },
    },
    ProjectionExpression: "apiKey"
  };

  chaveAPI = await ddb.getItem(params, function (err, data) {
    if (err) {
      console.log("Error", err);
    } else {
      console.log("Success", data.Item);
    }
  });
};

EDIT1：修复了验证错误但仍然无法从 dyname 获取数据。这里是固定的

exports.apiKey = async (req, res) => {
    console.log("comecei")

    var params = {
        TableName: tableName,
        Key: {
          'username': {S: req.user.username}
        },
        ProjectionExpression: 'apiKey'
      };
      
      // Call DynamoDB to read the item from the table
      dataFromDynamo = await ddb.getItem(params, function(err, data) {
        if (err) {
          console.log("Error", err);
        } else {
          console.log("Success", data.Item);
          return data.Item
        }
      });

console.log(dataFromDynamo)

};

Answer 1

我从您的代码示例中注意到一些事情：

您将回调与 async/await 混合使用。
您没有声明 dataFromDynamo 变量。

而不是这个

     // Call DynamoDB to read the item from the table
     dataFromDynamo = await ddb.getItem(params, function(err, data) {
        if (err) {
          console.log("Error", err);
        } else {
          console.log("Success", data.Item);
          return data.Item
        }
      });

这样做

try {
    // Call DynamoDB to read the item from the table
    const dataFromDynamo = await ddb.getItem(params).promise()
    console.log("Success", data.Item);
    return data.Item
} catch (err) {
    console.log("Error", err);
}

从 dynamoDB getItem 导出值

export values from dynamoDB getItem

amazon-web-services

node.js

amazon-dynamodb