AWS SDK for .NET
Developer Guide

This documentation is for version 2.0 of the AWS SDK for .NET. For the latest version, see the AWS SDK for .NET Developer Guide for version 3.

JSON Support in Amazon DynamoDB with the AWS SDK for .NET

The AWS SDK for .NET supports JSON data when working with Amazon DynamoDB. This enables you to more easily get JSON-formatted data from, and insert JSON documents into, DynamoDB tables.

Get Data from a DynamoDB Table in JSON Format#

The following example shows how to get data from a DynamoDB table in JSON format:

// using Amazon.DynamoDBv2;
// using Amazon.DynamoDBv2.DocumentModel;

var client = new AmazonDynamoDBClient();
var table = Table.LoadTable(client, "AnimalsInventory");
var item = table.GetItem(3, "Horse");

var jsonText = item.ToJson();
Console.Write(jsonText);
      
// Output:
//   {"Name":"Shadow","Type":"Horse","Id":3}

var jsonPrettyText = item.ToJsonPretty();
Console.WriteLine(jsonPrettyText);
      
// Output:
//   {
//     "Name" : "Shadow",
//     "Type" : "Horse",
//     "Id"   : 3
//   }

In the preceding example, the Document class's ToJson method converts an item from the table into a JSON-formatted string. The item is retrieved through the Table class's GetItem method. To determine the item to get, in this example, the GetItem method uses the hash-and-range primary key of the target item. To determine the table to get the item from, the Table class's LoadTable method uses an instance of the AmazonDynamoDBClient class and the name of the target table in DynamoDB.

Insert JSON Format Data into a DynamoDB Table#

The following example shows how to use JSON format to insert an item into a DynamoDB table:

// using Amazon.DynamoDBv2;
// using Amazon.DynamoDBv2.DocumentModel;

var client = new AmazonDynamoDBClient();
var table = Table.LoadTable(client, "AnimalsInventory");
var jsonText = "{\"Id\":6,\"Type\":\"Bird\",\"Name\":\"Tweety\"}";
var item = Document.FromJson(jsonText);

table.PutItem(item);

In the preceding example, the Document class's FromJson method converts a JSON-formatted string into an item. The item is inserted into the table through the Table class's PutItem method, which uses the instance of the Document class that contains the item. To determine the table to insert the item into, the Table class's LoadTable method is called, specifying an instance of the AmazonDynamoDBClient class and the name of the target table in DynamoDB.

DynamoDB Data Type Conversions to JSON#

Whenever you call the Document class's ToJson method, and then on the resulting JSON data you call the FromJson method to convert the JSON data back into an instance of a Document class, some DynamoDB data types will not convert as expected. Specifically:

  • DynamoDB sets (the SS, NS, and BS types) will be converted to JSON arrays.
  • DynamoDB binary scalars and sets (the B and BS types) will be converted to base64-encoded JSON strings or lists of strings.

In this scenario, you must call the Document class's DecodeBase64Attributes method to replace the base64-encoded JSON data with the correct binary representation. The following example replaces a base64-encoded binary scalar item attribute in an instance of a Document class, named Picture, with the correct binary representation. This example also does the same for a base64-encoded binary set item attribute in the same instance of the Document class, named RelatedPictures:

item.DecodeBase64Attributes("Picture", "RelatedPictures");

Additional Resources#

For additional information and examples of programming JSON with DynamoDB with the the SDK, see: