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AWS Documentation » AWS SDK for .NET » Developer Guide » Code Examples » Using Amazon DynamoDB NoSQL Databases » JSON Support in Amazon DynamoDB with the AWS SDK for .NET

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 ToJson method of the Document class converts an item from the table into a JSON-formatted string. The item is retrieved through the GetItem method of the Table class. 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 LoadTable method of the Table class 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 FromJson method of the Document class converts a JSON-formatted string into an item. The item is inserted into the table through the PutItem method of the Table class, which uses the instance of the Document class that contains the item. To determine the table to insert the item into, the LoadTable method of the Table class 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 ToJson method of the Document class, 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 be converted 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 DecodeBase64Attributes method of the Document class 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");

More Info

For more information and examples of programming JSON with DynamoDB with the AWS SDK for .NET, see: