Add option for failing on unknown JSON Schema type #471

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1. bcherny

   added

   enhancement

   help wanted

   good first issue

   on Aug 6, 2022
2. cesarvspr commented on Oct 2, 2022

   

   cesarvspr

   on Oct 2, 2022

   More actions

   @Winded would you please provide and example of schema that is translated to unknown typescript type?
3. Winded commented on Oct 11, 2022

   

   Winded

   on Oct 11, 2022

   Author

   More actions

   I modified the example JSON to have invalid type for a field:

   {
     "title": "Person",
     "type": "object",
     "properties": {
       "firstName": {
         "type": "string"
       },
       "lastName": {
         "type": "asd"
       },
       "age": {
         "description": "Age in years",
         "type": "integer",
         "minimum": 0
       },
       "hairColor": {
         "enum": ["black", "brown", "blue"],
         "type": "string"
       }
     },
     "required": ["firstName", "lastName"]
   }

   This results in generated code:

   /* tslint:disable */
   /**
    * This file was automatically generated by json-schema-to-typescript.
    * DO NOT MODIFY IT BY HAND. Instead, modify the source JSONSchema file,
    * and run json-schema-to-typescript to regenerate this file.
    */
   
   export interface Person {
     firstName: string;
     lastName: {
       [k: string]: unknown;
     };
     /**
      * Age in years
      */
     age?: number;
     hairColor?: "black" | "brown" | "blue";
     [k: string]: unknown;
   }
4. tlahav commented on Oct 20, 2022

   

   tlahav

   on Oct 20, 2022

   Contributor

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   Hi, looking a bit at this request. Does it make sense to add a 'strict' mode in the options and throw exception if we have a case of 'UNKNOWN'? or would that be too heavy handed?

   I noticed there's also options.unknownAny. Should we still allow for those UNKNOWNs even in this new 'strict' mode?
5. bcherny

   added

   auto-repro-checked

   on Aug 2, 2026
6. rishilifts commented on Oct 13, 2026

   

   rishilifts

   on Oct 13, 2026

   More actions

   I'd like to work on this. My proposed scope is an opt-in rejectInvalidTypes option: reject invalid explicit type values, but keep valid unconstrained schemas working. unknownAny would stay independent. I'd include CLI support and regression tests. Is that scope still wanted? I'll use AI assistance and disclose it in the PR.