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Lets Playing with servicenow Table API using Postman

You can programmatically add records to a table in ServiceNow by creating a POST API for the table. This tutorial will show you how to use Postman to create and test a POST table API.

For clarity, screenshots are added at each stage.

Step 1. Open ServiceNow and navigate to the Table.

  1. Open your ServiceNow instance and log in.
  2. Locate the table for which you wish to develop the API using the Application Navigator. If you'd like to use a different table.
  3. Go to Tables under System Definition.
  4. To create a custom table, click New.
  5. Name the table and specify its fields.
    ServiceNow

Step 2. Give the Table API Access.

  1. Go to System Definition > Tables to open the table configuration.
  2. Find your table and pick it.
  3. Enable the Allow Access via Web Services option in the table settings to make sure the table may be accessed via an API.
  4. Click "Save."

Create the POST API in step three.

  1. Go to REST API Explorer under System Web Services.
  2. From the dropdown menu, choose the table you wish to work with.
  3. Select the HTTP method POST.
    Rest API
  4. Define the JSON payload in the Request Body section. Like below. 
    { 
"short_description" : "Testing post" , 
"description" : "Testing post" 
}
  5. To test the API in ServiceNow, click Send.

Step 4. Set up authentication for the API.

  • Verify that the person using the API has the appropriate roles. Usually, the user needs the proper table permissions or the rest_api_explorer role.
  • To manage the user's roles, go to System Security > Roles.

Step 5. Use Postman to test the API.

1. Make a fresh request.

2. Establish Headers.

Add the following to the Headers tab.

  • Type of Content.
  • Application/JSON
  • Accept: json/application

3. Include Authentication.

  • Pick Basic Auth from the Authorization tab.
  • Enter your password and ServiceNow username.
  • like eg
  • Username - admin, password - welcome123'
    Send

4. Include the payload in JSON.

  • Click on the Body tab.
  • Choose raw and select JSON as the payload type.
  • Paste the JSON that follows. 
    {
  "short_description": "Testing post",
  "description": "Testing post"
}

5. Send the Request

Click Send to execute the request.

Step 6. Confirm the Answer.

  1. Look for the status code in the Postman response window. A 201 Created answer will be returned if the request is successful.
  2. The information about the newly generated record, including the sys_id, will be included in the response body.
    Response body

Step 7. Verify the ServiceNow record.

  1. Return to ServiceNow and navigate back to the table.
  2. Check to see if the values in the JSON payload were used to build the new record.
    Record

Best Practices

  1. Use Scoped Applications: To improve version control and maintainability, encapsulate your table and API functionality.
  2. Use Access Control: Put ACLs (Access Control Rules) into place to limit access to private information and guarantee safe API use.
  3. Test in Development: Prior to implementing API changes in production, always test them in a development or sandbox instance.
  4. Log API Usage: To keep an eye on API usage and spot possible problems, turn on logging.
  5. Verify Inputs: Use server-side validation to make sure that incoming data follows the specified formats and limitations.
  6. Optimize Performance: To make API interactions with big tables run more smoothly, use indexing and effective queries.
  7. Document API Endpoints: Keep your API documentation current, covering error codes, expected answers, and payload structure.
  8. Utilize ServiceNow's API capabilities: To improve API functionality, make use of response filtering, query parameters, and other integrated capabilities.
  9. Secure Credentials: Use environment variables or secret management technologies for authentication instead of hard-coding sensitive credentials.
  10. Limit Data Exposure: To lower the chance of overexposure, use table-specific API views to reveal just the fields that are required.
  11. Monitor and Audit: To spot odd activity or security breaches, keep a close eye on audit logs and API usage.
  12. Use Rate Limiting: By establishing rate limitations, you may prevent your instance from becoming overloaded with too many API queries.

In the next article, let's see how to handle these parameters dynamically from a diff service instance; until then, bye happy learning.


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