asmhatreandClaude Opus 5
926250e1a9
Companion code for "Global Exception Handling with ProblemDetail (RFC 9457) in Spring Boot 4". Thirteen failures under five handling setups (Boot defaults, the Boot flag, a ResponseEntityExceptionHandler advice, advice plus an ErrorController, a catch-all ordered first), validation errors, i18n, content negotiation, Security's 401/403, silent 500s and decoding on the client. 16 tests pin the behaviour. Co-Authored-By: Claude Opus 5 <[email protected]> Claude-Session: https://claude.ai/code/session_01C3TETMrqVUWeFkNtz3Jbo3
43 lines
1.6 KiB
Markdown
43 lines
1.6 KiB
Markdown
# 8. The client side: decoding problems with `RestClient`
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[← 7. Silent 500s](07-silent-500s.md) · [Index](../README.md)
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`RestClient`'s default status handler throws `HttpClientErrorException` /
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`HttpServerErrorException`; `getResponseBodyAs(ProblemDetail.class)` decodes the body with the
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client's converters. [`/diag/decode`](../src/main/java/com/ankurm/problems/diag/DiagController.java)
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reports what came back ([`client-decoding.txt`](output/client-decoding.txt)).
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## What works
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Extension members land in `getProperties()` - `orderId`, the `errors` list, `errorId`. The mixin
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works in both directions.
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## Two things to code defensively against
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**`getType()` is `null` when the server omitted it**, which Spring Framework 7 servers do for every
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framework error ([chapter 4](04-i18n-and-types.md)). Treat `null` as `about:blank`.
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**Decoding succeeds on a body that is not a problem at all.** Against the `defaults` profile the
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server sends Boot's `application/json` error, and it still decodes:
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```
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"exception": "org.springframework.web.client.HttpServerErrorException$InternalServerError",
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"status": 500,
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"contentType": "application/json",
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"problemDetail": {
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"type": "null",
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"title": "Internal Server Error",
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"status": 500,
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"detail": null,
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"instance": "null",
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"properties": {
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"timestamp": "2026-09-11T17:05:01.408Z",
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"error": "Internal Server Error",
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"path": "/orders/999"
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}
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}
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```
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Unknown members go into `properties`, so any JSON object "is" a `ProblemDetail`. Check the
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`Content-Type` is `application/problem+json` before believing you have one.
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