如何使用 NodeJS 在 AWS Dynamo DB 中進行更新

Question

我寫了這個 function 在發電機表中進行更新

const updateTask = async (req, res) => {
  try {
    const { existingTaskText,updatedTaskText } = req.body;
    console.log(existingTaskText,updatedTaskText );
    UPDATE({
      TableName: "todos",
      Key:{ task: existingTaskText},
      UpdateExpression:"set task = :task",
      ExpressionAttributeValues: {":task": updatedTaskText},
    });
    res.status(200).json({ data: "this is controller" });
  } catch (error) {
    res.status(400).json({ message: error.message });
  }
};

這是調用 UPDATE

const UPDATE = async (payload) => {
  try {
    console.log(payload);
    const updateDoc = await dbClient
      .update({
        TableName: payload.TableName,
        Key: payload.Key,
        UpdateExpression: payload.UpdateExpression,
        ExpressionAttributeNames:payload.ExpressionAttributeNames,
        ReturnValues: "UPDATED_NEW",
      })
      .promise();
    console.log(updateDoc);
  } catch (error) {
    console.log(error);
  }
};

當我在 postman 中測試這個時，我收到了這個錯誤

ValidationException: Invalid UpdateExpression: An expression attribute value used in expression is not defined; attribute value: :task

這是通過的有效負載日志

{
  TableName: 'todos',
  Key: { task: 'see its  done' },
  UpdateExpression: 'set task = :task',
  ExpressionAttributeValues: { ':task': 'edited' }
}

Answer 1

我為更新、獲取和創建表創建了以下常用函數。使用相同。

const AWS = require('aws-sdk');
AWS.config.update({ region: "us-east-1",accessKeyId : process.env.AWS_ACCESS_KEY_ID, secretAccessKey: process.env.AWS_SECRET_ACCESS_KEY });
const dynamoDB = new AWS.DynamoDB()
const documentClient = new AWS.DynamoDB.DocumentClient();

const Dynamo = {
    async get(id, TableName) {
        const params = {
            TableName,
            Key: {
                id,
            },
        };

        const data = await documentClient.get(params).promise();

        if (!data || !data.Item) {
           throw Error(`There was an error fetching the data for ID of ${id} from ${TableName}`);
           
        }
        console.log(data);

        return data.Item;
    },
    async getall(TableName) {
        const params = {
            TableName: TableName,
          };

        const data = await documentClient.scan(params).promise();

        if (!data || !data.Item) {
            throw Error(`There was an error fetching the data for ID of ${ID} from ${TableName}`);
        }
        console.log(data);

        return data.Items;
    },
    async getMany(params) {
        const data = await documentClient.scan(params).promise();
        console.log(data);
        if (!data || !data.Items) {
            throw Error(`There was an error fetching the data`);
        }

        return data.Items;
    },

    async write(data, TableName) {
        console.log('write dynamo',data, TableName);
        if (!data.id) {
            throw Error('no ID on the data');
        }

        const params = {
            TableName,
            Item: data,
        };

        const res = await documentClient.put(params).promise();

        if (!res) {
            throw Error(`There was an error inserting ID of ${data.id} in table ${TableName}`);
        }
        console.log('res of write dynamo ',res);
        return data;
    },
    async createTable(TableName) {
    documentClient
    .scan({
            TableName: TableName,
        })
    .promise()
    .catch(error => {
  
        return new Promise(resolve => {
            dynamoDB
            .createTable({
              AttributeDefinitions: [
                {
                  AttributeName: "id",
                  AttributeType: "S",
                },
              ],
              KeySchema: [
                {
                  AttributeName: "id",
                  KeyType: "HASH",
                },
              ],
              BillingMode: "PAY_PER_REQUEST",
              TableName: TableName,
            })
            .promise()
            .then(data => console.log("Success!", data))
            .catch(console.error)
        })
      });

    },

};
module.exports = Dynamo;

Answer 2

當您調用 dbClient.update 方法時，您正在聲明參數 ExpressionAttributeNames。 它應該是 ExpressionAttributeValues。 這就是為什么錯誤消息表明未定義表達式中使用的表達式屬性值的原因。

因此，您可以嘗試以這種方式更改 dbClient.update 調用：

const updateDoc = await dbClient
  .update({
    TableName: payload.TableName,
    Key: payload.Key,
    UpdateExpression: payload.UpdateExpression,
    ExpressionAttributeValues:payload.ExpressionAttributeValues,
    ReturnValues: "UPDATED_NEW",
  })
  .promise();