DynamoDB Array of Array of strings schema

Question

I'm looking for assistance on how I can achieve the schema below into my dynamodb database.

Example of my JSON

var users = [{
    userId: 123,
    userName: "John Smith",
    additionalInfomation: [
      ["favoriteColor", "blue"], 
      ["hobbies", "ping-pong"]
    ]
}]

This is what I have so far to achieve the userId and userName schema. I'm having trouble setting up additionalInfomation part.

  const params = {
    AttributeDefinitions: [
      {
        AttributeName: 'userId',
        AttributeType: 'N'
      },
      {
        AttributeName: 'userName',
        AttributeType: 'S'
      },
      {
        AttributeName: 'additionalInformation',
        AttributeType: <NEED HELP HERE> // <-------------------- ?????
      }
    ],
    KeySchema: [
      {
        AttributeName: 'userId',
        KeyType: 'HASH'
      },
      {
        AttributeName: 'userName',
        KeyType: 'RANGE'
      },
      {
        AttributeName: 'additionalInformation',
        KeyType: <NEED HELP HERE> // <-------------------- ?????
      }
    ],
    ProvisionedThroughput: {
      ReadCapacityUnits: 1,
      WriteCapacityUnits: 1
    },
    TableName: 'USERS',
    StreamSpecification: {
      StreamEnabled: false
    }
  };
  // Call DynamoDB to create the table
  ddb.createTable(params, function(err, data) {
    if (err) {
      console.log('Error', err);
    } else {
      console.log('Table Created', data);
    }
  });

Need help setting the additionalInformation schema up. Please excuse my ignorance if this isn't the right approach. Still learning dynamoDB and the aws doc isn't quite helpful for a beginner.

matsev · Accepted Answer · 2019-05-28 20:00:01Z

4

For this use case, I recommend that you choose either userId or userName as your HASH key (aka partition key) for your table, assuming that either of this attributes will uniquely identify the user. RANGE key (aka sort key) are beneficial when you have several items associated with one partition key, c.f. artists and song titles in the Primary Key paragraph of the DynamoDB user guide. Consequently, this means that you only need to specify one attribute in the AttributeDefinitions and KeySchema.

Furthermore, I recommend that you omit the additionalInformation from your schema based on the assumption that you will neither use that information as partition key nor a sort key.

Instead, you can add them as two separate attributes to individual items when calling putItem() or updateItem (or the corresponding put() and update() functions if you use the DynamoDB DocumentClient).

const params = {
  Item: {
   "userId": {
     N: "123"
    }, 
   "userName": {
     S: "dummy"
    }, 
   "favoriteColor": {
     S: "blue"
    },
   "hobbies": {
     SS: ["ping-pong", "another hobby"]
    }
  }, 
  TableName: "USERS"
 };
 const putItemPromise = dynamodb.putItem(params).promise()

Note, in the example above I have specified favoriteColor as S, i.e. a single string, but the hobbies as SS meaning that it is a array of strings. This may or may not what you want, but since the attribute name is "hobbies" (and not "hobby"), I figured that it would make sense to allow more than one.

edited May 28, 2019 at 20:00

answered May 28, 2019 at 19:36

matsev

34k18 gold badges128 silver badges169 bronze badges

Sign up to request clarification or add additional context in comments.

5 Comments

Victor Le Over a year ago

I appreciate your knowledge about the HASH and RANGE key. But there's a reason why I needed it as a type of [["key", "value"], ["key", "value"]]. Can you update your answer to allow for that use case? Each nested array will always have a size of two and both are strings. Empty string is okay

matsev Over a year ago

This is not supported AFAIK. Maybe you can implement a workaround by using a string array that you then split manually, e.g. something like "additionalInfomation": {SS: ["key#value", "key#value"] }

Victor Le Over a year ago

it's okay I solved it. additionalInformation: { L: [ {SS: ["", ""] }, {SS: ["", ""] } ] }

matsev Over a year ago

I stand corrected, I had overlooked the L (List) and the M (Map) Attribute Values (see also the DynamoDB Data Types)

Victor Le Over a year ago

Thanks. That helped a lot! I wished the aws documentation had more examples 😅

Collectives™ on Stack Overflow

DynamoDB Array of Array of strings schema

1 Answer 1

5 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

5 Comments

Your Answer

Sign up or log in

Post as a guest

Related