API Best Practices

Multipart Boundary Handling for Import APIs

Preset and Superset import APIs (for example, dashboard, chart, and dataset imports) accept files using multipart/form-data requests. Correct handling of multipart boundaries is required for these endpoints to parse request payloads successfully.

This section explains how multipart boundaries work and provide guidance on how to avoid common request-formatting errors.

Why Multipart Boundaries Matter

When sending files using multipart/form-data, the HTTP request body is split into parts using a boundary string. This boundary must:

• Be present in the Content-Type request header
• Match the boundary used to encode the request body

If the boundary is missing or mismatched, the server cannot correctly parse the request. In this case, import APIs will fail with a generic error, such as:

{"message": "Arguments are not correct"}

Common Pitfall: Manually Setting Content-Type

A common cause of import failures is manually setting the Content-Type header to:

Content-Type: multipart/form-data

without including a boundary.

Many HTTP client libraries (including Python requests) automatically generate the correct Content-Type header with a boundary when a file upload is provided. If you override this header manually, the client library will not inject the boundary, resulting in an invalid request.

Recommended Approach

When calling Preset or Superset import APIs:

• Do not manually set the Content-Type header
• Allow your HTTP client to generate the header automatically
• Provide files using the client’s native multipart upload mechanism

Python (requests) Example

files = {"formData": open("dashboard.zip", "rb")}
payload = {"overwrite": True}

requests.post(
    url,
    headers={"Authorization": f"Bearer {token}"},
    data=payload,
    files=files,
)

In this example, requests automatically sets:

Content-Type: multipart/form-data; boundary=...

ensuring the request can be parsed correctly.

Affected APIs

This behavior applies to all Preset and Superset APIs that accept file uploads via multipart form data, including:

• Dashboard import
• Chart import
• Dataset import
• Database import (when applicable)
• Content migration endpoints

The same boundary-handling rules apply to all of these endpoints.

Troubleshooting Import Errors

If an import API returns:

{"message": "Arguments are not correct"}

verify the following:

• The request uses multipart/form-data
• The Content-Type header includes a boundary
• The Content-Type header is not manually overridden
• Files are passed using the correct form field name (for example, formData)
• Additional parameters (such as passwords or overwrite) are valid and correctly formatted