swagger-api/swagger-codegen

Bad error message on accidentally nested schema.

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#2,313 opened on Mar 4, 2016

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Enhancement: GeneralGeneral: Suggestionhelp wanted

Description

When I build a spec (here: https://gist.github.com/nicksloan/0ec7e74af30ac9540ccf) with a schema nested within a schema (see line #647) I am shown a less than helpful error message:

[main] WARN io.swagger.util.PropertyDeserializer - no property from null, null, {ENUM=null, TITLE=null, DESCRIPTION=Unexpected error, DEFAULT=null, PATTERN=null, DESCRIMINATOR=null, MIN_ITEMS=null, MAX_ITEMS=null, MIN_PROPERTIES=null, MAX_PROPERTIES=null, MIN_LENGTH=null, MAX_LENGTH=null, MINIMUM=null, MAXIMUM=null, EXCLUSIVE_MINIMUM=null, EXCLUSIVE_MAXIMUM=null, UNIQUE_ITEMS=null, EXAMPLE=null, TYPE=null, FORMAT=null, READ_ONLY=null, VENDOR_EXTENSIONS={}}

Using the online validator in debug mode is much more helpful in identifying the actual issue:

{"schemaValidationMessages":[{"level":"error","domain":"validation","keyword":"oneOf","message":"instance failed to match exactly one schema (matched 0 out of 2)","schema":{"loadingURI":"http://swagger.io/v2/schema.json#","pointer":"/definitions/responseValue"},"instance":{"pointer":"/paths/~1infomous-graph/get/responses/default"}}]}

The codegen version is 2.1.5 from Homebrew.

Contributor guide

Tech stack
javarest api
Domain
backendapideveloper experience
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
mostly clear
Prerequisites
Understanding of JSON SchemaFamiliarity with Swagger/OpenAPI specJava programming basics
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
50
Research direction
The issue reports a bad error message in swagger codegen when a schema is nested incorrectly. The error originates from PropertyDeserializer, which prints raw property details instead of a user friendly validation error. The fix should improve error handling to output a clear message, possibly by integrating the validation logic from the online validator. Relevant file: modules/swagger codegen/src/main/java/io/swagger/util/PropertyDeserializer.java.