> ## Documentation Index
> Fetch the complete documentation index at: https://docs.nx1cloud.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Create an Engineer API

> Create an Engineer API to apply transformation rules and expose the transformed data via API endpoints for your app.

Creating an Engineer API grants you the ability to transform data within your desired app. It leverages the existing data
transformation and preparation rules, which modify data to meet specific goals. This could include a rule to summarize the data,
remove duplicate rows, or convert the data format.

## Prerequisites

* Appropriate permission: `nx1_engineer`
* An existing domain created using [DataHub](/platform-components/datahub)
* A previously ingested dataset within a DataHub domain

## Select a dataset and describe a transformation rule

<Tabs>
  <Tab title="Web portal" icon="browser">
    The catalog contains metadata about the schema and table.
    The schema describes the data structure, such as the table name, column names, and data types. The table contains the data.

    1. Log in to NexusOne.
    2. On the top navigation bar, hover your mouse over **Data Pipeline** and then select **Engineer**.
    3. If you are working with multiple catalogs, then click **Federated > Select catalogs** and choose at least two catalogs.
       Else, click **Lakehouse > Select catalogs** and choose the Iceberg catalog.
    4. Select schemas from each catalog.
    5. Select tables from each catalog.

    You describe a rule using natural language so that NexusOne can generate an SQL query.

    1. Enter a transformation job name.
    2. Enter a natural language transformation prompt.
    3. Optional: Select the **Show preview?** checkbox if you'd like a preview of your data after running the generated query from the
       prompt input you have provided.
    4. Click **Transform**. If you selected the preview checkbox in the previous step, then also click **Finalize**
       to proceed to the next step.
  </Tab>

  <Tab title="CLI" icon="square-terminal">
    Use the following `nx1` command to [ask and generate a data engineering query](/cli-reference/nx1/ask).
  </Tab>

  <Tab title="REST API" icon="code">
    Use the following API endpoint to [ask and generate a data engineering query](/api-reference/endpoints/data-engineering/ask-eng).
  </Tab>
</Tabs>

## Schedule a transformation rule

<Tabs>
  <Tab title="Web portal" icon="browser">
    Scheduling a rule allows you to run the rule at specific time intervals using Apache AirFlow.

    1. Select a destination schema.
    2. Select a destination table.
    3. Select a [DataHub](/platform-components/datahub/datahub-in-nx1) domain.
    4. Optional: Select or create one or more tags to label this rule.
    5. Select a time interval for how often the transformation rule should run.
       Schedule options include `None`, `Every 3 hours`, `Daily`, `Weekly`, `Monthly`, and `Quarterly`. On the first schedule,
       the job/DAG on Apache Airflow automatically runs. Recurrent runs depend on your selected schedule option.
    6. Select a mode for how to store incoming records at the destination table.
       * **Append**: Add new records.
       * **Merge**: Add or update existing records where applicable.
       * **Overwrite**: Replace all existing records.
  </Tab>

  <Tab title="REST API" icon="code">
    Use the following API endpoint to [schedule a query](/api-reference/endpoints/data-engineering/schedule-query).
  </Tab>
</Tabs>

## Create an Engineer API

You create an API so you can transform data within your desired app.

1. Select the previously chosen DataHub domain.
2. Enter a name for the API.
3. Select the **nx1\_engineer** role.
4. Click **Create**.
5. View your Data API and API key:
   * On the NexusOne homepage, navigate to **Connect > Data API** to view your Data API.
   * Click **API Keys** from the navigation sidebar to view your API key. If you have a long list of keys present,
     use the filter by description or key field to find the API key.

## Additional resources

* For general instructions about how to ingest a file in NexusOne, refer to [How to ingest a file](/documentation/data-pipeline/tasks/ingest/ingest-a-file).
* For more information about the monitoring feature, refer to [Monitor Overview](/documentation/platform/overview/monitor).
* For more information about roles or permissions, refer to [Govern Overview](/documentation/govern/overview).