V4: toJSONSchema z.literal is missing "type" #4249

marclp-es · 2025-04-20T18:02:11Z

I am using toJSONSchema to generate an openapi schema for gemini and it is complaining that "type" is missing when using z.literal() compared to using v3 with zod-to-json-schema, I am not sure if this is intended, an oversight, or google's APIs are very picky. Here is an example of a simple json schema produced in v3 vs the same in v4 using z.toJSONSchema.

V3:

{
  "type": "object",
  "properties": {
    "test": {
      "type": "string",
      "const": "test"
    }
  },
  "required": [
    "test"
  ],
  "additionalProperties": false,
  "$schema": "http://json-schema.org/draft-07/schema#"
}

V4:

{
  "type": "object",
  "properties": {
    "test": {
      "const": "test"
    }
  },
  "required": [
    "test"
  ]
}

samchungy · 2025-04-21T00:30:37Z

const is technical valid by itself so it seems Google is picky. In my own library I made the decision to always include type as a number of different libraries which rely on spec aren't always compliant. But to be fair to them, the spec can be iffy at times.

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V4: toJSONSchema z.literal is missing "type" #4249

V4: toJSONSchema z.literal is missing "type" #4249

V4: toJSONSchema z.literal is missing "type" #4249

V4: toJSONSchema z.literal is missing "type" #4249

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