Tutorial: Call a Third-Party API from a Trigger

Navigate to the Values page.

In Atlas, go to the Triggers page.

1. If it's not already displayed, select the organization that contains your project from the Organizations menu in the navigation bar.

2. If it's not already displayed, select your project from the Projects menu in the navigation bar.

3. In the sidebar, click Triggers under the Streaming Data heading.

The Triggers page displays.

1. Click the View All Apps button.

2. Click the app that you want to create the Trigger in.

3. In the sidebar, click Values under the Build heading.

Store the access key ID.

1. Click Create a Value.

2. Enter AwsAccessKeyId as the Value Name.

3. Select the Value type.

4. Select the Custom Content option and enter your AWS access key ID.

   Note

   You must enter the access key ID as a string value with quotes ("<accessKeyId>").

5. Click Save Draft.

Store the secret access key.

1. Click Create a Value.

2. Enter AwsSecretAccessKey as the Value Name.

3. Select the Value type.

4. Select the Link to Secret option.

5. Enter AwsSecretAccessKeySecret and click Create "AwsSecretAccessKeySecret" to name the Secret.

   Paste your AWS secret access key into the field that appears below the Secret name.

6. Click Save Draft to create both the Secret and the Value.

Navigate to the Triggers page.

In Atlas, go to the Triggers page.

1. If it's not already displayed, select the organization that contains your project from the Organizations menu in the navigation bar.

2. If it's not already displayed, select your project from the Projects menu in the navigation bar.

3. In the sidebar, click Triggers under the Streaming Data heading.

The Triggers page displays.

Create the Trigger.

1. Click Add Trigger to open the Trigger configuration page.

2. Select the Database Trigger type, then configure the Trigger using the following values:

   Setting	Value
   Trigger Name	WriteDocumentToS3Trigger
   Watch Against	Collection
   Cluster Name	Name of your test cluster
   Database Name	Name of your test database
   Collection Name	Name of your test collection
   Operation Type	Select only Insert.
   Event Type	Function

3. In the Function section, select + New Function.

Add the aws-sdk dependency.

1. In the Function section, click Add Dependency.

2. In the Add Dependency window, enter aws-sdk as the Define a Package Name and leave Package Version blank to use the latest version.

3. Click Add to add the package.

Enter the following code to define the Function.

Replace YOUR_AWS_REGION and YOUR_S3_BUCKET_NAME with your own AWS Region and the full bucket name from the AWS Management Console.

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/*
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 * Write a newly-inserted document to an S3 bucket as an Extended JSON object.
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 */
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exports = async function writeDocumentToS3(changeEvent) {
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  const { fullDocument } = changeEvent;
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  // require calls must be in the exports function
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  const S3 = require("aws-sdk/clients/s3");
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  const s3 = new S3({
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    accessKeyId: context.values.get("AwsAccessKeyId"),
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    secretAccessKey: context.values.get("AwsSecretAccessKey"),
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    region: "YOUR_AWS_REGION",
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  });
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  const key = `inserted-documents/${fullDocument._id.toString()}.json`;
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  // https://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/S3.html#putObject-property
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  await s3.putObject({
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    Bucket: "YOUR_S3_BUCKET_NAME",
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    Key: key,
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    Body: EJSON.stringify(fullDocument),
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    ContentType: "application/json",
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  }).promise();
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  return `Wrote document ${fullDocument._id} to ${key}`;
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};

Each time a document is inserted, the Function does the following:

• Reads the inserted document from the change event's fullDocument field.

• Creates an S3 client that authenticates with the AWS credentials stored in your Values.

• Writes the document to the inserted-documents/ prefix of your bucket as <_id>.json.

Click Save to create the Trigger.

Connect to your cluster with mongosh.

To learn how, see Connect to a Cluster via mongosh.

Insert a document into the collection that the Trigger watches.

The following example inserts one document into the test collection. Replace YOUR_DATABASE_NAME and YOUR_COLLECTION_NAME with the database and collection that you entered when you created the Trigger.

// Replace YOUR_DATABASE_NAME and YOUR_COLLECTION_NAME with the
// database and collection that the Trigger watches.
use YOUR_DATABASE_NAME
db.YOUR_COLLECTION_NAME.insertOne({
  tutorialTest: "atlas-trigger-s3",
  createdAt: new Date()
})

{
  acknowledged: true,
  insertedId: ObjectId('6accda8d1bed071fd18dc505')
}

Note the insertedId value from your output. The Function uses this value as the name of the S3 object.

Confirm that the object exists in your S3 bucket.

In the AWS Management Console, open your S3 bucket and navigate to the inserted-documents/ prefix. An object named <insertedId>.json appears, where <insertedId> is the insertedId value from the previous step.