how to retrieve values from dynamodb by lambda function

Question

I need to retrieve values from dynamodb by lambda function

import boto3
from boto3.dynamodb.conditions import Key, Attr

    dynamodb = boto3.resource('dynamodb')
    table = dynamodb.Table(os.environ['DB_TABLE_NAME'])
    postItem = table.query(
        KeyConditionExpression=Key('id').eq(postId)
    )

I get the following error:

{
  "errorMessage": "Syntax error in module 'lambda_function'"
}

Answer 1

You need a lambda handler in your code and you need to import os module as well. This might get you started.

import boto3
import os
from boto3.dynamodb.conditions import Key, Attr

def lambda_handler(event, context):

    postId = event["postId"]

    dynamodb = boto3.resource('dynamodb')
    table = dynamodb.Table(os.environ['DB_TABLE_NAME'])

    if postId=="*":
        items = table.scan()
    else:
        items = table.query(
            KeyConditionExpression=Key('id').eq(postId)
        )

    return items["Items"]