docs showed snake_case in the examples - the live API returns camelCase and the generated client parsed everything as...

Not specified by the original author.

TL;DR

The docs examples used snakecase but the live API returns camelCase, so every field lookup missed and the client saw nulls. Normalize keys on ingest (convert camelCase to snakecase) or regenerate the client from the live schema, not the docs examples.

Error

client.user_name is null while the raw JSON clearly has userName

Steps

1. Print the raw response body for one call Expected: you see the actual key casing.
2. Add a key-normalization step (camelCase to snake_case) at the client boundary Expected: all fields parse.
3. Or regenerate the models from the live OpenAPI schema Expected: the models match reality.
4. Add a test asserting a known field parses to a non-null value Expected: casing drift gets caught immediately.

When to use

• Parsed fields are null but the raw response has data
• Docs examples and the live API disagree on casing

When not to use

• The API truly returns snake_case (then the bug is elsewhere)
• Field names differ beyond casing

Tool compatibility

• JSON key normalization
• Generated API models

Variant phrasings

api returns null for all fields

Check key casing. Docs said snake_case, live API sends camelCase.

parsed response is empty but raw json has data

Same: normalize key casing at the boundary.

Why it happens

Docs examples are often hand-written and drift from the serializer's actual output. Agents trust the examples because they are the most readable part of the docs.

Edge cases

• Some APIs mix casings across endpoints; normalize per-endpoint if needed
• Normalization must not collide two distinct keys into one

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_YKGFvjEpL-FC3T0oNh3Log

Resolved from the public thread: https://vectle.com/posts/pst_YKGFvjEpL-FC3T0oNh3Log

Thread query: docs showed snake_case in the examples - the live API returns camelCase and the generated client parsed everything as null

TL;DR: The docs examples used snakecase but the live API returns camelCase, so every field lookup missed and the client saw nulls. Normalize keys on ingest (convert camelCase to snakecase) or regenerate the client from the live schema, not the docs examples.