DynamoDB CRUD operations.ts

import {
  DynamoDBClient,
  PutItemCommand,
  GetItemCommand,
  UpdateItemCommand,
  DeleteItemCommand,
} from '@aws-sdk/client-dynamodb';
import {
  marshall,
  unmarshall
} from '@aws-sdk/util-dynamodb';
import { SUCCESS, FAILURE } from '../constants';

const TABLE_NAME = 'test-table';
const REGION = 'ap-southeast-1';

interface Result {
  status: string,
  data?: any
}

// 1. Add new item to the db
const add = async (
  item: {
    PK: string
    SK: string
  }) => {
  const client = new DynamoDBClient({ region: REGION });
  const params = {
    TableName: TABLE_NAME,
    Item: marshall({
      ...item,
      created: new Date().toISOString()
    })
  };

  try {
    const command = new PutItemCommand(params);
    const result = await client.send(command);

    return new Promise<Result>(resolve => {
      if (result.$metadata.httpStatusCode === 200) {
        resolve({
          status: SUCCESS
        });
      } else {
        resolve({
          status: FAILURE
        });
      }
    });
  } catch (e) {
    throw e;
  }
}

// 2. Query item from db
const get = async (key: {
  PK: string
  SK: string
}) => {
  const client = new DynamoDBClient({ region: REGION });
  const params = {
    TableName: TABLE_NAME,
    Key: marshall(key)
  };

  try {
    const command = new GetItemCommand(params);
    const result = await client.send(command);

    return new Promise<Result>(resolve => {
      if (result.$metadata.httpStatusCode === 200) {
        resolve({
          status: SUCCESS,
          data: unmarshall(result.Item)
        });
      } else {
        resolve({
          status: FAILURE
        });
      }
    });
  } catch (e) {
    throw e;
  }
}

// 3. Update one attribute on given record
const updateAttibute = async ({
  key,
  item
}: {
  key: {
    PK: string
    SK: string
  },
  item: {
    [key: string]: number | string
  }
}) => {
  if (Object.keys(item).length !== 1) {
    throw Error('Cannot update multiple arributes at once.');
  }
  const client = new DynamoDBClient({ region: REGION });
  const params = {
    TableName: TABLE_NAME,
    Key: marshall(key),
    ConditionExpression: `attribute_exists(${Object.keys(item)[0]})`,
    UpdateExpression: 'set #a = :x',
    ExpressionAttributeNames: { '#a': Object.keys(item)[0] },
    ExpressionAttributeValues: marshall({
      ':x': Object.values(item)[0]
    }),
  };

  try {
    const command = new UpdateItemCommand(params);
    const result = await client.send(command);

    return new Promise<Result>(resolve => {
      if (result.$metadata.httpStatusCode === 200) {
        resolve({
          status: SUCCESS
        });
      } else {
        resolve({
          status: FAILURE
        });
      }
    });
  } catch (e) {
    throw e;
  }
}

// 4. Replace old record with new item
const replace = async ({
  key,
  item
}: {
  key: {
    PK: string
    SK: string
  },
  item: {
    [key: string]: number | string
  }
}) => {

  const client = new DynamoDBClient({ region: REGION });
  const params = {
    TableName: TABLE_NAME,
    Item: marshall({
      key,
      ...item,
      updated: new Date().toISOString()
    })
  };

  try {
    const command = new PutItemCommand(params);
    const result = await client.send(command);

    return new Promise<Result>(resolve => {
      if (result.$metadata.httpStatusCode === 200) {
        resolve({
          status: SUCCESS
        });
      } else {
        resolve({
          status: FAILURE
        });
      }
    });
  } catch (e) {
    throw e;
  }
}

// 5. Remove record 
const remove = async (key: {
  PK: string
  SK: string
}) => {
  const client = new DynamoDBClient({ region: REGION });
  const params = {
    TableName: TABLE_NAME,
    Key: marshall(key),
  };

  try {
    const command = new DeleteItemCommand(params);
    const result = await client.send(command);

    return new Promise<Result>(resolve => {
      if (result.$metadata.httpStatusCode === 200) {
        resolve({
          status: SUCCESS
        });
      } else {
        resolve({
          status: FAILURE
        });
      }
    });
  } catch (e) {
    throw e;
  }
}

export default {
  add,
  get,
  updateAttibute,
  replace,
  remove
}