Dynamo DB Query Filter Node.js

Question

Running a Node.js serverless backend through AWS.

Main objective: to filter and list all LOCAL jobs (table items) that included the available services and zip codes provided to the filter.

Im passing in multiple zip codes, and multiple available services.

data.radius would be an array of zip codes = to something like this:[ '93901', '93902', '93905', '93906', '93907', '93912', '93933', '93942', '93944', '93950', '95377', '95378', '95385', '95387', '95391' ]

data.availableServices would also be an array = to something like this ['Snow removal', 'Ice Removal', 'Salting', 'Same Day Response']

I am trying to make an API call that returns only items that have a matching zipCode from the array of zip codes provided by data.radius, and the packageSelected has a match of the array data.availableServices provided.

API CALL

import * as dynamoDbLib from "./libs/dynamodb-lib";
import { success, failure } from "./libs/response-lib";

export async function main(event, context) {
  const data = JSON.parse(event.body);
  const params = {
    TableName: "jobs",
    FilterExpression: "zipCode = :radius, packageSelected = :availableServices",
    ExpressionAttributeValues: {
      ":radius": data.radius,
      ":availableServices": data.availableServices
    }
  };

  try {
    const result = await dynamoDbLib.call("query", params);
    // Return the matching list of items in response body
    return success(result.Items);
  } catch (e) {
    return failure({ status: false });
  }

Do I need to map the array of zip codes and available services first for this to work?

Should I be using comparison operators? https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/LegacyConditionalParameters.QueryFilter.html

Is a sort key value or partition key required to query and filter? (the table has a sort key and partition key but i would like to avoid using them in this call)

Im not 100% sure on how to go about this so if anyone could point me in the right direction that would be wonderful and greatly appreciated!!

Still trying to figure this out! lol its been a dog.

Jordan Spackman
– Jordan Spackman

2020-01-13 18:03:39 +00:00
Commented Jan 13, 2020 at 18:03 — Jordan Spackman
– Jordan Spackman, Commented Jan 13, 2020 at 18:03

jarmod · Accepted Answer · 2020-01-13 19:49:28Z

4

I'm not sure what your dynamodb-lib refers to but here's an example of how you can scan for attribute1 in a given set of values and attribute2 in a different set of values. This uses the standard AWS JavaScript SDK, and specifically the high-level document client.

Note that you cannot use an equality (==) test here, you have to use an inclusion (IN) test. And you cannot use query, but must use scan.

const AWS = require('aws-sdk');

let dc = new AWS.DynamoDB.DocumentClient({'region': 'us-east-1'});

const data = {
  radius: [ '93901', '93902', '93905', '93906', '93907', '93912', '93933', '93942', '93944', '93950', '95377', '95378', '95385', '95387', '95391' ],
  availableServices: ['Snow removal', 'Ice Removal', 'Salting', 'Same Day Response'],
};

// These hold ExpressionAttributeValues
const zipcodes = {};
const services = {};

data.radius.forEach((zipcode, i) => {
  zipcodes[`:zipcode${i}`] = zipcode;
})

data.availableServices.forEach((service, i) => {
  services[`:services${i}`] = service;
})

// These hold FilterExpression attribute aliases
const zipcodex = Object.keys(zipcodes).toString();
const servicex = Object.keys(services).toString();

const params = {
  TableName: "jobs",
  FilterExpression: `zipCode IN (${zipcodex}) AND packageSelected IN (${servicex})`,
  ExpressionAttributeValues : {...zipcodes, ...services},
};

dc.scan(params, (err, data) => {
  if (err) {
    console.log('Error', err);
  } else {
    for (const item of data.Items) {
      console.log('item:', item);
    }
  }
});

edited Jan 13, 2020 at 19:49

answered Jan 13, 2020 at 19:10

jarmod

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1 Comment

Jordan Spackman Over a year ago

with a little tweaking for my application, it works! Thank you very much!

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