File content displays incorrectly in the viewer

Summary

This issue appears when Clockspring does not know the correct mime.type for a FlowFile. The UI falls back to a generic or unknown type, which causes JSON, XML, or text content to render incorrectly.

Symptom

When opening a FlowFile in the content viewer you see:

• The viewer defaults to text or unknown

• JSON appears as a single long line

• The mime.type attribute shows unknown

• The preview is not formatted as expected

Root Cause

One or more of the following is true:

• The FlowFile has no mime.type attribute

• The mime.type attribute contains the wrong value

• The upstream processor did not set a content type

• InvokeHTTP returned a response without a Content-Type header

• The viewer uses its fallback mode because it cannot determine the format

How to Fix It

Option A: Set mime.type manually

If you know the content type:

1. Add an UpdateAttribute processor

2. Set mime.type to the correct value

   • application/json

   • text/csv

   • text/plain

   • application/xml

Option B: Use IdentifyMimeType

This processor analyzes the FlowFile content and sets mime.type automatically.

Use it when the content is a file, binary data, or text where the type is not provided.

Option C: Configure InvokeHTTP

For APIs this is usually the best fix.

Set Override Response Content-Type to the expected value.
Examples:

• application/json

• text/plain

• application/xml

This ensures all responses carry the correct type, even if the API does not specify one.

Option D: Change the viewer mode manually

If you only need to fix the display once:

• In the FlowFile content viewer, use the dropdown in the top right

• Select json, xml, csv, or text as needed
  This does not update mime.type on the FlowFile. It only adjusts the display.

Prevention

• Always set Override Response Content-Type on InvokeHTTP when calling APIs that return JSON

• Use IdentifyMimeType early in flows where files may come from unknown sources

• Standardize mime.type handling in your templates so content always renders correctly