Load Preview data to DuckDB

Contentstack Preview Service API allows developers to retrieve unpublished content for previewing purposes by providing specific stack credentials and preview tokens. Everything needed to build a working Preview → DuckDB pipeline is on this page: the API's base URL, authentication, endpoints, pagination and incremental field — plus a prompt that hands the whole job to your coding agent.

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Build your Preview to DuckDB pipeline

Paste this prompt into Claude, Codex, or Cursor. The agent does the rest.

PromptCopy prompt
Run uvx dlthub-init@latest to build a pipeline from Preview to DuckDB and run it on dltHub

That scaffolds a dltHub workspace and installs the dltHub AI harness — the project rules, the secrets-management skill, and the dlt MCP server your agent needs to work safely. From there it reads the Preview API, proposes the endpoints to load, then writes, runs and validates the pipeline while you review rather than type. Credentials are inspected through MCP tools, so your agent never reads secrets.toml itself. How the LLM-native workflow works →

Prefer to write it yourself? Every fact the agent uses is below.

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Preview API at a glance

These values come from the Preview API reference — the authoritative source if anything here looks out of date.

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How do I authenticate with the Preview API?

All requests to the Contentstack Preview Service API require the stack API key and a preview token passed as HTTP headers.

1. Get your credentials

To obtain API credentials for a REST service, first consult the official developer portal or API documentation for the service you are targeting (e.g., GitHub, Notion, Stripe). Once you have your credentials (typically an API key, client ID/secret, or access token), add them securely to the .dlt/secrets.toml file in your project directory. For security, never hardcode these values directly in your pipeline scripts; instead, reference them using dlt.secrets["sources.<source_name>.<key_name>"]. You may also use the dlt init command, which often scaffolds the necessary structure and prompts for the required configuration.

2. Add them to .dlt/secrets.toml

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[sources.preview_source]
api_key = "your_actual_api_key_here"
# OR for OAuth2 based flows
# client_id = "your_client_id_here"
# client_secret = "your_client_secret_here"

dlt reads this file automatically at runtime. With the harness, the setup-secrets skill prompts you for the values and never handles the raw credential in chat. For production, see setting up credentials with dlt.

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What Preview data can I load into DuckDB?

These are the Preview endpoints dlt can load into DuckDB:

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How do I load only new Preview records?

Preview exposes offset on content/preview/api/v1.1/items, so dlt can request only the records that changed since the last run. Set it as the cursor_path and dlt tracks the high-water mark for you between runs.

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{"name": "items", "endpoint": {
    "path": "content/preview/api/v1.1/items",
    "data_selector": "items",
    "incremental": {"cursor_path": "offset", "initial_value": "2024-01-01T00:00:00Z"},
}}

On the first run dlt loads everything from initial_value; on every run after that it requests only what changed and appends with write_disposition="merge" if you set a primary key. See incremental loading.

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What does the generated Preview pipeline look like?

A standard dlt REST API pipeline — the same code you would write by hand, loading client and resources (or endpoint) from the Preview API into DuckDB:

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import dlt
from dlt.sources.rest_api import RESTAPIConfig, rest_api_resources

@dlt.source
def preview_source(preview_token=dlt.secrets.value):
    config: RESTAPIConfig = {
        "client": {
            "base_url": "https://rest-preview.contentstack.com/v3",
            "auth": {"type": "bearer", "token": preview_token},
        },
        "resources": [
            {"name": "items", "endpoint": {"path": "content/preview/api/v1.1/items", "data_selector": "items"}},
            {"name": "item_details", "endpoint": {"path": "content/preview/api/v1.1/items/{id}"}}
        ],
    }
    yield from rest_api_resources(config)


def load_preview_to_duckdb() -> None:
    pipeline = dlt.pipeline(
        pipeline_name="preview_pipeline",
        destination="duckdb",
        dataset_name="preview_data",
    )
    load_info = pipeline.run(preview_source())
    print(load_info)


if __name__ == "__main__":
    load_preview_to_duckdb()

Run it with python preview_pipeline.py. The agent iterates on this until it loads cleanly — you review and approve, rather than write it from scratch.

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How do I query Preview data in DuckDB?

dlt creates one table per resource. Query the loaded data with Python or SQL — or ask your agent to, through the MCP server's execute_sql_query tool.

Python (pandas DataFrame):

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import dlt

data = dlt.pipeline("preview_pipeline").dataset()
df = data.items.df()
print(df.head())

SQL:

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SELECT * FROM preview_data.items LIMIT 10;

See querying your data with dataset and exploring it in marimo notebooks.

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How do I deploy the Preview to DuckDB pipeline in production?

The pipeline runs locally, which is ideal for prototyping and one-off analysis. When you need it on a schedule, monitored on every load, and shared with your team, deploy the same dlt code on the dltHub platform — no infrastructure to maintain. The prompt above already ends with "run it on dltHub", so your agent can take it there directly.

• Deploy & schedule — run the pipeline as a managed job with automatic retries.
• Monitor — observable job queues, alerting, and load metrics for every run.
• Transform — promote raw Preview loads into governed, documented models.
• Visualize & share — explore data in notebooks and publish live dashboards instead of static screenshots.

Book a demo →

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What other destinations can I load Preview data to?

dlt loads into any of these — only the destination argument changes:

Set dlt.pipeline(destination="snowflake") and add credentials in .dlt/secrets.toml. On the dltHub platform the same pipeline runs against a managed Iceberg lakehouse. See the full destinations list.

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Next steps

• Ready for production? Book a demo of the dltHub platform →
• dlt LLM-native workflow docs
• REST API source reference
• Join the dlt community on Slack