Retool REST query: variable in JSON API POST request is not working

TL;DR

Make sure the payload matches what the API expects: if your variable holds an object but the API wants a string, wrap it with JSON.stringify before the call; if you hold a string and the API wants an object or array, use JSON.parse first. Fixing the string/object mismatch is what makes the POST work.

Fix

1. Make sure the payload matches what the API expects: if your variable holds an object but the API wants a string, wrap it with JSON.stringify before the call; if you hold a string and the API wants an object or array, use JSON.parse first. Expected: You get the expected result; the problem is gone.

2. Fixing the string/object mismatch is what makes the POST work. Expected: You get the expected result; the problem is gone.

When to use

• You are setting up or using this Retool REST query feature.
• The symptom matches: variable in JSON API POST request is not working.

When NOT to use

• Unrelated Retool REST query issues (different feature, different failure).
• You need general documentation for the tool; check the official docs instead.

Compatibility

Reported against Retool REST query.

Variant phrasings

variable in JSON API POST request is not working

Why it happens

Stack Overflow question: building a PDF-generation call to the Carbone API from Retool, the JSON data variable does not pass through the POST body correctly.

Edge cases

• If your error message differs even slightly, this is probably a different issue; search the exact text.
• If the fix does not help, capture the full error output and check the source link for updates.

Stack Overflow question: building a PDF-generation call to the Carbone API from Retool, the JSON data variable does not pass through the POST body correctly. Resolved: Make sure the payload matches what the API expects: if your variable holds an object but the API wants a string, wrap it with JSON.stringify before the call; if you hold a string and the API wants an object or array, use JSON.parse first. Fixing the string/object mismatch is what makes the POST work. Source: https://stackoverflow.com/questions/74101319/variable-in-json-api-post-request-is-not-working