Exercise: Create a CRUD Service

This page lists an exercise for adding a new MongoDB-backed state to Train CRUD and exposing it as a /test endpoint.

This exercise extends the existing Train CRUD runner with a new state. The result is a new CRUD endpoint under the runner. The endpoint reads and writes to a MongoDB collection automatically.

Before you start

• You can access the Devops app.

• The training deployment is installed and train_crud is running.

• You know your API base URL: https://[YOUR_ADMIN_API_DOMAIN].

What you’ll build

• A new state with alias test.

• A new endpoint: https://[YOUR_ADMIN_API_DOMAIN]/api/request/train_crud/test

1

Open the Runner screen

Open the Runner screen from the Devops app.

Unless you changed routing, the UI is at https://[YOUR_ADMIN_UI_DOMAIN]/app/devops/common/runner.

Runner UI

2

Select Train CRUD

In the left runner list, filter and select Train CRUD.

Train CRUD Runner

3

Add a new State element

Drag a State element (table icon) from the stencil onto the runner diagram.

Select the new element. Click the pencil icon to edit it.

New State Manager

4

Configure it as Generic Master + alias test

In the editor:

• Choose Generic Master.

• Set alias to test.

Generic Master creates a simple MongoDB-backed state manager on the master database. The alias becomes:

• the CRUD URL segment (/test)

• the MongoDB collection name (test)

This is the simplest “new CRUD resource” configuration. For advanced options, use the Devops docs referenced from the CRUD runner section.

5

Wait for rebuild and test the endpoint

The training Train CRUD runner is typically configured to rebuild every ~30 seconds. After you save, give it a moment to apply the new state.

Then call:

https://[YOUR_ADMIN_API_DOMAIN]/api/request/train_crud/test

Expected result:

• HTTP 200 OK

• Body: {list: []} (the collection starts empty)

Full list of supported CRUD operations and parameters is in CRUD event runner.

Troubleshooting

• 404 Not Found: confirm the alias is test and that you saved the runner. Then wait for the rebuild interval.

• 500 errors: Generic Master points to a MongoDB connection. Check the master DB is reachable.

• Endpoint exists but returns nothing: verify you are hitting train_crud (URL contains /train_crud/).