I have created a KNIME flow to connect to a AI API and translate a specific column in English. I loop trough each line of the column, in the string manipulation I have added the LLM instructions, Post request contains the API key, Json path creates the translation column. everything works very well and I get the result that I want. The problem is that I have transferred the flow to another colleague using the same data and he gets this error on the Json Path: “Execute failed: Input table’s structure differ from reference (first iteration) Table: Column 98 [body(JSON)]vs[body(Binary object)]“. it fail at the first iteration, column 98 is the body column, you can see the content in the picture. do you have any idea why we have this problem?
@CYLE Based on the error message, the first iteration returned a Binary Object, while the current instance returned JSON.
Currently, you cannot force REST nodes to output a specific column type (we have a ticket for this: AP-21611).
Possible workarounds
Loop End Settings: Check the box “Allow changing table specifications”. This allows the loop to continue even if the column type changes from Binary to JSON between iterations.
Filter Rows: Alternatively, use a Rule-based Row Splitter (e.g., Status = 200 or content type like json) before the JSON Path node. This ensures only valid JSON rows are processed, avoiding the mismatch entirely.
Hello @k10shetty1 thank you for your reply! before trying your approach, I noticed in further iterations is that the error sometimes disappear. another time I got the same error because the body column came out of the POST REQUEST as type: BLOB. is your proposal going to fix this random behavior?
@CYLE Could you please share the Status and Content type values for the specific rows where the Body column is appearing as a Binary Object (BLOB)?
The POST Request node usually outputs a BLOB when the API returns a response type it doesn’t recognize as standard JSON ( an HTML error page, a text file, etc.).
Knowing the Content-type will help determine if we can convert that BLOB to a String (using Binary Objects to Strings) or if the API is returning a different file type.
