DynamoDB DocumentClient typescript definitions seem to be incorrect

Hi, I am using the DocumentClient with typescript.

The type definitions seem to be incorrect:

• The DocumentClient always returns JSON instead of an AttributeMap.

Here is the output of the type definitions document_client.d.ts for GetItem

export interface GetItemOutput {
    Item?: AttributeMap;
    ...
}
export type AttributeMap = {[key: string]: AttributeValue};
/**
   * A JavaScript object or native type.
   */
export type AttributeValue = any;

Note that the type definitions in dynamodb.d.ts of AttributeValue is different than in the document_client.d.ts (it also contains the same interfaces…):

export interface GetItemOutput {
   Item?: AttributeMap;
   ...
}
export interface AttributeValue {
    S?: StringAttributeValue;
   ...
}

As the documentation of the document client says,

A JavaScript object or native type. Should I cast it to JSON?

In my package.json I use "aws-sdk": "^2.341.0", which includes the type definitions.

Here is the hacky code (JavaScript code copied from the DDB js tutorial) to reproduce the result as JSON (DocumentClient) vs a result with AttributeValues (DynamoDB):

var AWS = require('aws-sdk');
AWS.config.update({
  region: 'eu-west-1'
});
const tableName = 'table-name'
const KEY = 'abc'
var ddb = new AWS.DynamoDB({
  apiVersion: '2012-08-10'
});
var params = {
  RequestItems: {
    'table-name': {
      Keys: [{
        'key_id': {
          S: KEY
        }
      }]
    }
  }
};

ddb.batchGetItem(params, function (err, data) {
  if (err) {
    console.log("Error", err);
  } else {
    data.Responses[tableName].forEach(function (element, index, array) {
      console.log(element);
    });
  }
});
const docClient = new AWS.DynamoDB.DocumentClient();

const params2 = {
  ConsistentRead: true,
  RequestItems: {
    [tableName]: {
      Keys: [{
        "key_id": KEY
      }]
    },
  },
}
docClient.batchGet(params2, function (err, data) {
  if (err) {
    console.log("Error", err);
  } else {
    data.Responses[tableName].forEach(function (element, index, array) {
      console.log('----------------------------------------');
      console.log(' doc client output: ');
      console.log(element);
      console.log('----------------------------------------');
    });
  }
});

Clearly the doc client output does not contain the AttributeValue types (e.g. {"S": "foo"})

// raw DDB client
key_id: { S: 'abc' }

// DocumentClient output
key_id: 'abc'

It seems that the client is auto-generated. https://github.com/aws/aws-sdk-js/blob/master/apis/dynamodb-2012-08-10.normal.json

Are the definitions up-to-date?

Thx. Simon

[simonmit]

Thanks for the fast reply. The behaviour of the DocumentClient is correct. The issue is about the type definitions: There are type definitions with overlapping types (which differ slightly).

I found out that the the issue is in how VS Code lets me navigate to the respective type definition files. I was able to convince VS Code to use the correct type:

// import { GetItemOutput } from 'aws-sdk/clients/dynamodb';
import { DocumentClient } from 'aws-sdk/clients/dynamodb';

const resp: DocumentClient.GetItemOutput = ...

So this is not an issue of the type definitions. It was my fault to rely on VS Code to point me to the correct type definition. I will close the issue.

[Jefftopia]

@srchase I just went down a little rabbit hole on this. Would be very helpful to document and note this in the d.ts files.

// These types...
import {
    DocumentClient,
    PutItemInput
} from 'aws-sdk/clients/dynamodb';

// Do not align with these types
import {
    DocumentClient as DocClient
} from 'aws-sdk/lib/dynamodb/document_client';

// DocClient.PutItemInput vs  PutItemInput

Having the top import path export the class but not do much to note the two different sets of interfaces is confusing. I had to fish for the ones in the DocumentClient namespace.