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Create DynamoDB Tables with Node.js

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Create DynamoDB Tables with Node.js

In this post, we look at how to create tables in DynamoDB using Node.js.

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Before getting started, we need to have local DynamoDB installed since we want to avoid any costs for DynamoDB usage. There was a previous post on local DynamoDB.

If you use Docker, you can find a local DynamoDB image, or you can create one on you own as described here.

Using local DynamoDB and Node.js is extremely handy for debugging. Local DynamoDB provides us with a web user interface on http://localhost:8000/shell. The local DynamoDB shell is a JavaScript shell, therefore the actions for Node.js can be issued straight to the DynamoDB shell.

The actions would be the same as described in the corresponding Java tutorial.

The first step is to create a table with a hash key. In this case, the email of the user would be the hash key.

var createUsers = function(callback) {

    var dynamodb = new AWS.DynamoDB();

    var params = {
        TableName : "Users",
        KeySchema: [       
        { AttributeName: "email", KeyType: "HASH"}
    ],
    AttributeDefinitions: [       
        { AttributeName: "email", AttributeType: "S" }
    ],
    ProvisionedThroughput: {       
        ReadCapacityUnits: 5, 
        WriteCapacityUnits: 5
   }
};

dynamodb.createTable(params, callback);
};


The next table will be called Logins. Logins should keep track each time the user logged in. To do so apart from using a hash key, we will also use a range key for the date it occurred.

var createLogins = function(callback) {

    var dynamodb = new AWS.DynamoDB();

    var params = {
        TableName : "Logins",
        KeySchema: [       
            { AttributeName: "email", KeyType: "HASH"},
            { AttributeName: "timestamp", KeyType: "RANGE"}
            ],
        AttributeDefinitions: [       
            { AttributeName: "email", AttributeType: "S" },
            { AttributeName: "timestamp", AttributeType: "N" }
            ],
        ProvisionedThroughput: {       
            ReadCapacityUnits: 5, 
            WriteCapacityUnits: 5
           }
        };
dynamodb.createTable(params, callback);
};


The next table is Supervisors. The hash key of Supervisor would be his name. A supervisor will work for a company. The company will be our global secondary index. Since the companies own more than one factories the field factory would be the range key.

var createSupervisors = function(callback) {

    var dynamodb = new AWS.DynamoDB();

    var params = {
        TableName : "Supervisors",
        KeySchema: [       
            { AttributeName: "name", KeyType: "HASH"}
            ],
        AttributeDefinitions: [       
            { AttributeName: "name", AttributeType: "S" },
            { AttributeName: "company", AttributeType: "S" },
            { AttributeName: "factory", AttributeType: "S" }    
        ],
    ProvisionedThroughput: {       
        ReadCapacityUnits: 5, 
        WriteCapacityUnits: 5
        },
    GlobalSecondaryIndexes: [{
        IndexName: "FactoryIndex",
        KeySchema: [
            {
                AttributeName: "company",
                KeyType: "HASH"
                },
            {
                AttributeName: "factory",
                KeyType: "RANGE"
            }
        ],
        Projection: {
            ProjectionType: "ALL"
            },
        ProvisionedThroughput: {
            ReadCapacityUnits: 1,
            WriteCapacityUnits: 1
            }
        }]
    };
dynamodb.createTable(params, callback);
};


The next table would be the table Companies. The hash key would be the parent company and the range key the subsidiary company. Each company has a CEO. The CEO would be the range key for the local secondary index.

var createCompanies = function(callback) {

    var dynamodb = new AWS.DynamoDB();

    var params = {
        TableName : "Companies",
        KeySchema: [       
            { AttributeName: "name", KeyType: "HASH"},
            { AttributeName: "subsidiary", KeyType: "RANGE"}
            ],
        AttributeDefinitions: [       
            { AttributeName: "name", AttributeType: "S" },
            { AttributeName: "subsidiary", AttributeType: "S" },
            { AttributeName: "ceo", AttributeType: "S" }    
            ],
        ProvisionedThroughput: {       
            ReadCapacityUnits: 5, 
            WriteCapacityUnits: 5
           },
        LocalSecondaryIndexes: [{
            IndexName: "CeoIndex",
            KeySchema: [
                {
                    AttributeName: "name",
                    KeyType: "HASH"
                    },
                {
                    AttributeName: "ceo",
                    KeyType: "RANGE"
                    }
                ],
            Projection: {
            ProjectionType: "ALL"
            }
        }]
    };
dynamodb.createTable(params, callback);
};

You can find the source code on GitHub.

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Topics:
dynamodb ,tables ,create ,node.js ,code

Published at DZone with permission of Emmanouil Gkatziouras, DZone MVB. See the original article here.

Opinions expressed by DZone contributors are their own.

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