Apollo DynamoDB Data Source

This package exports a (DynamoDBDataSource) class which is used for fetching data from a DynamoDB Table and exposing it via GraphQL within Apollo Server.

Documentation

View the Apollo Server documentation for data sources for more details.

Usage

To get stated, install the apollo-datasource-dynamodb packageL

# with npm
npm install --save apollo-datasource-dynamodb
# with yarn
yarn add apollo-datasource-dynamodb

To define a data source, extend the DynamoDBDataSource class and pass in the name of the table, the Key schema, and the ClientConfiguration that allows the lib to connect to the DynamoDB.DocumentClient to interact with data in the table. Creating an instance of this class then allows you to utilize the API methods.

Example

Say you have a DynamoDB table called test_data which has a Schema:

{
  TableName: 'test_hash_only',
  KeySchema: [{ AttributeName: 'id', KeyType: 'HASH' }],
  AttributeDefinitions: [{ AttributeName: 'id', AttributeType: 'S' }],
  ProvisionedThroughput: {
    ReadCapacityUnits: 1,
    WriteCapacityUnits: 1,
  },
}

Here is an example interface of the items that will be returned from this table:

interface TestHashOnlyItem {
  id: string;
  test: string;
}

To use the DynamoDBDataSource we create a class that subclasses this Data Source and can then implement API:

// ./src/data-sources/test-hash-only.datasource.ts

import { DynamoDBDataSource } from 'apollo-datasource-dynamodb';
import { DocumentClient } from 'aws-sdk/clients/dynamodb';

class TestHashOnly extends DynamoDBDataSource<TestHashOnlyItem> {
  private readonly tableName = 'test_hash_only';
  private readonly tableKeySchema: DocumentClient.KeySchema = [
    {
      AttributeName: 'id',
      KeyType: 'HASH',
    },
  ];
  private readonly ttl = 30 * 60; // 30minutes

  constructor(config?: ClientConfiguration) {
    super(this.tableName, this.tableKeySchema, config);
  }

  async getTestHashOnlyItem(id: string): Promise<TestHashOnlyItem> {
    const getItemInput: DocumentClient.GetItemInput = {
      TableName: this.tableName,
      ConsistentRead: true,
      Key: { id },
    };
    return this.getItem(getItemInput, this.ttl);
  }

  async scanForTestHashOnlyItems(): Promise<TestHashOnlyItem[]> {
    const scanInput: DocumentClient.ScanInput = {
      TableName: this.tableName,
      ConsistentRead: true,
    };
    return this.scan(scanInput, this.ttl);
  }
}

And then to utilize this instance as a data source in the ApolloServer instance:

// ./src/server.ts

import { ApolloServer } from 'apollo-server-lambda';
import { TestHashOnly } from './data-sources/test-hash-only.datasource';

const server = new ApolloServer({
  typeDefs,
  resolvers,
  dataSources: () => ({
    testHashOnly: new TestHashOnly(),
  }),
});

The to use the use the TestHashOnly data source in the resolvers:

// ./src/schema.ts

import { gql, IResolvers } from 'apollo-server-lambda';
import { DocumentNode } from 'graphql';

export const typeDefs: DocumentNode = gql`
  type TestHashOnlyItem {
    id: String!
    test: String!
  }

  type Query {
    getTestHashOnlyItem(id: String!): TestHashOnlyItem
    scanHashOnlyItems: [TestHashOnlyItem]
  }
`;

export const resolvers: IResolvers = {
  Query: {
    getTestHashOnlyItem: async (_source, { id }, { dataSources }) => dataSources.testHashOnly.getTestHashOnlyItem(id),
    scanHashOnlyItems: async (_source, _params, { dataSources }) => dataSources.testHashOnly.scanForTestHashOnlyItems(),
  },
};

API

getItem

this.getItem(getItemInput, 180)

Returns a single instance of the item being retrieved from the table by the key value. It checks the cache for the record, if the value is found in the cache, it returns the item, otherwise it uses the DynamoDB.DocumentClient.get method to retrieve the item from the table; if a record is found in the table, it is then added to the cache with the passed in ttl.

DynamoDB.DocumentClient.get

getItem Example

const getItemInput: DocumentClient.GetItemInput = {
  TableName: 'test_hash_only',
  ConsistentRead: true,
  Key: {
    id: 'testId',
  },
};
const ttl = 30 * 60; // 30minutes

const item: TestHashOnlyItem = await this.getItem(getItemInput, ttl);

query

this.query(queryInput, 180)

Returns all records from the table found by the query. If the ttl is provided, it adds all of the items to the cache.

DynamoDB.DocumentClient.query

query Example

const queryInput: DynamoDB.DocumentClient.QueryInput = {
  TableName: 'test_hash_only',
  ConsistentRead: true,
  KeyConditionExpression: 'id = :id',
  ExpressionAttributeValues: {
    ':id': 'testId',
  },
};
const ttl = 30 * 60; // 30minutes

const items: TestHashOnlyItem[] = await this.query(queryInput, ttl);

scan

this.scan(scanInput, 180)

Returns all scanned records from the table by the scanInput. A scan is different from a query because in a query a portion of the key schema on the table must be provided. A scan allows you to retrieve all items from the table, it also lets you paginate.

DynamoDB.DocumentClient.scan

scan Example

const scanInput: DynamoDB.DocumentClient.ScanInput = {
  TableName: 'test_hash_only',
  ConsistentRead: true,
};
const ttl = 30 * 60; // 30minutes

const items: TestHashOnlyItem[] = await this.scan(scanInput, ttl);

put

this.put(item, 180)

Saves the given item to the table. If a ttl value is provided it will also add the item to the cache

DynamoDB.DocumentClient.put

put Example

const item: TestHashOnlyItem = {
  id: 'testId2',
  test: 'testing2',
};
const ttl = 30 * 60; // 30minutes

const created: TestHashOnlyItem = await this.put(item, ttl);

update

this.update(key, updateExpression, expressionAttributeNames, expressionAttributeValues, 180)

Updates the item in the table found by the given key and then uses the update expressions to update the record in the table. These input values are used to build a DocumentClient.UpdateItemInput instance to tells DynamoDB how to update the record.

DynamoDB.DocumentClient.update

update Example

const key: DocumentClient.Key = {
  id: 'testId',
};
const updateExpression: DocumentClient.UpdateExpression = 'SET #test = :test';
const expressionAttributeNames: DocumentClient.ExpressionAttributeNameMap = { '#test': 'test' };
const expressionAttributeValues: DynamoDB.DocumentClient.ExpressionAttributeValueMap = {
  ':test': 'testing_updated',
};
const ttl = 30 * 60; // 30minutes

const updated: TestHashOnlyItem = await this.update(
  key,
  updateExpression,
  expressionAttributeNames,
  expressionAttributeValues,
  ttl
);

delete

this.delete(key)

Deletes the item found by the key from the table. It also evicts the item from the cache.

DynamoDB.DocumentClient.delete

delete Example

const key: DocumentClient.Key = {
  id: 'testId',
};

await this.delete(key);