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title description author ms.service ms.subservice ms.devlang ms.topic ms.date ms.author ms.custom
Build an Azure Cosmos DB Node.js application by using Gremlin API
Presents a Node.js code sample you can use to connect to and query Azure Cosmos DB
jasonwhowell
cosmos-db
cosmosdb-graph
nodejs
quickstart
06/05/2019
jasonh
devx-track-js

Quickstart: Build a Node.js application by using Azure Cosmos DB Gremlin API account

[!div class="op_single_selector"]

In this quickstart, you create and manage an Azure Cosmos DB Gremlin (graph) API account from the Azure portal, and add data by using a Node.js app cloned from GitHub. Azure Cosmos DB is a multi-model database service that lets you quickly create and query document, table, key-value, and graph databases with global distribution and horizontal scale capabilities.

Prerequisites

Create a database account

[!INCLUDE cosmos-db-create-dbaccount-graph]

Add a graph

[!INCLUDE cosmos-db-create-graph]

Clone the sample application

Now let's clone a Gremlin API app from GitHub, set the connection string, and run it. You'll see how easy it is to work with data programmatically.

  1. Open a command prompt, create a new folder named git-samples, then close the command prompt.

    md "C:\git-samples"

  2. Open a git terminal window, such as git bash, and use the cd command to change to the new folder to install the sample app.

    cd "C:\git-samples"

  3. Run the following command to clone the sample repository. This command creates a copy of the sample app on your computer.

    git clone https://github.com/Azure-Samples/azure-cosmos-db-graph-nodejs-getting-started.git

  4. Open the solution file in Visual Studio.

Review the code

This step is optional. If you're interested in learning how the database resources are created in the code, you can review the following snippets. Otherwise, you can skip ahead to Update your connection string.

The following snippets are all taken from the app.js file.

This console app uses the open-source Gremlin Node.js driver.

  • The Gremlin client is created.

    const authenticator = new Gremlin.driver.auth.PlainTextSaslAuthenticator(
    `/dbs/${config.database}/colls/${config.collection}`, 
    config.primaryKey
)


const client = new Gremlin.driver.Client(
    config.endpoint, 
    { 
        authenticator,
        traversalsource : "g",
        rejectUnauthorized : true,
        mimeType : "application/vnd.gremlin-v2.0+json"
    }
);

    The configurations are all in config.js, which we edit in the following section.

  • A series of functions are defined to execute different Gremlin operations. This is one of them:

    function addVertex1()
{
    console.log('Running Add Vertex1'); 
    return client.submit("g.addV(label).property('id', id).property('firstName', firstName).property('age', age).property('userid', userid).property('pk', 'pk')", {
            label:"person",
            id:"thomas",
            firstName:"Thomas",
            age:44, userid: 1
        }).then(function (result) {
                console.log("Result: %s\n", JSON.stringify(result));
        });
}

  • Each function executes a client.execute method with a Gremlin query string parameter. Here is an example of how g.V().count() is executed:

    function countVertices()
{
    console.log('Running Count');
    return client.submit("g.V().count()", { }).then(function (result) {
        console.log("Result: %s\n", JSON.stringify(result));
    });
}

  • At the end of the file, all methods are then invoked. This will execute them one after the other:

    client.open()
.then(dropGraph)
.then(addVertex1)
.then(addVertex2)
.then(addEdge)
.then(countVertices)
.catch((err) => {
    console.error("Error running query...");
    console.error(err)
}).then((res) => {
    client.close();
    finish();
}).catch((err) => 
    console.error("Fatal error:", err)
);

Update your connection string

  1. Open the config.js file.

  2. In config.js, fill in the config.endpoint key with the Gremlin Endpoint value from the Overview page of your Cosmos DB account in the Azure portal.

    config.endpoint = "https://<your_Gremlin_account_name>.gremlin.cosmosdb.azure.com:443/";

    :::image type="content" source="./media/create-graph-nodejs/gremlin-uri.png" alt-text="View and copy an access key in the Azure portal, Overview page":::

  3. In config.js, fill in the config.primaryKey value with the Primary Key value from the Keys page of your Cosmos DB account in the Azure portal.

    config.primaryKey = "PRIMARYKEY";

    :::image type="content" source="./media/create-graph-nodejs/keys.png" alt-text="Azure portal keys blade":::

  4. Enter the database name, and graph (container) name for the value of config.database and config.collection.

Here's an example of what your completed config.js file should look like:

var config = {}

// Note that this must include the protocol (HTTPS:// for .NET SDK URI or wss:// for Gremlin Endpoint) and the port number
config.endpoint = "https://testgraphacct.gremlin.cosmosdb.azure.com:443/"; 
config.primaryKey = "Pams6e7LEUS7LJ2Qk0fjZf3eGo65JdMWHmyn65i52w8ozPX2oxY3iP0yu05t9v1WymAHNcMwPIqNAEv3XDFsEg==";
config.database = "graphdb"
config.collection = "Persons"

module.exports = config;

Run the console app

  1. Open a terminal window and change (via cd command) to the installation directory for the package.json file that's included in the project.

  2. Run npm install to install the required npm modules, including gremlin.

  3. Run node app.js in a terminal to start your node application.

Browse with Data Explorer

You can now go back to Data Explorer in the Azure portal to view, query, modify, and work with your new graph data.

In Data Explorer, the new database appears in the Graphs pane. Expand the database, followed by the container, and then select Graph.

The data generated by the sample app is displayed in the next pane within the Graph tab when you select Apply Filter.

Try completing g.V() with .has('firstName', 'Thomas') to test the filter. Note that the value is case sensitive.

Review SLAs in the Azure portal

[!INCLUDE cosmosdb-tutorial-review-slas]

Clean up your resources

[!INCLUDE cosmosdb-delete-resource-group]

Next steps

In this article, you learned how to create an Azure Cosmos DB account, create a graph by using Data Explorer, and run a Node.js app to add data to the graph. You can now build more complex queries and implement powerful graph traversal logic by using Gremlin.

[!div class="nextstepaction"] Query by using Gremlin