Unknown attributes AJV and typescript

[vongohren]

What version of Ajv are you using? Does the issue happen if you use the latest version?
8.11

Your typescript code

 type Typez = string | string[];
  interface Test {
    typez: Typez,
    [otherAttributes: string]: any;
  }

  const schema2: JSONSchemaType<Test> = {
    type: "object",
    properties: {
      typez: {
        anyOf: [{ type: "string"}, {type: "array", items: {type:"string"}}],
      }
    },
    additionalProperties: true,
    required:["typez"]
  }
  console.log(schema2)
}

Typescript compiler error messages

Type '{ type: "object"; properties: { typez: { anyOf: ({ type: "string"; } | { type: "array"; items: { type: "string"; }; })[]; }; }; additionalProperties: true; required: string[]; }' is not assignable to type 'UncheckedJSONSchemaType<Test, false>'.
  Types of property 'properties' are incompatible.
    Type '{ typez: { anyOf: ({ type: "string"; } | { type: "array"; items: { type: "string"; }; })[]; }; }' is not assignable to type 'UncheckedPropertiesSchema<Test>'.
      Property 'typez' is incompatible with index signature.
        Type '{ anyOf: ({ type: "string"; } | { type: "array"; items: { type: "string"; }; })[]; }' is not assignable to type '{ $ref: string; } | (UncheckedJSONSchemaType<any, false> & { nullable: true; const?: null | undefined; enum?: readonly any[] | undefined; default?: any; })'.
          Type '{ anyOf: ({ type: "string"; } | { type: "array"; items: { type: "string"; }; })[]; }' is not assignable to type '{ type: "null"; nullable: true; } & { allOf?: readonly UncheckedPartialSchema<any>[] | undefined; anyOf?: readonly UncheckedPartialSchema<any>[] | undefined; ... 4 more ...; not?: UncheckedPartialSchema<...> | undefined; } & { ...; } & { ...; }'.
            Type '{ anyOf: ({ type: "string"; } | { type: "array"; items: { type: "string"; }; })[]; }' is missing the following properties from type '{ type: "null"; nullable: true; }': type, nullablets(2322)

Describe the change that should be made to address the issue?
How shall I be able to represent the current type with ajv?
I did not find a solution in this issue: #1521

Are you going to resolve the issue?
I will resolve when I get some feedback

[epoberezkin]

JSONSchemaType doesn't support catch-all index syntax. Even with typescript, I think [otherAttributes: string]: any would allow any property to have any value, including typez, so it's probably not your intention... Although I might be wrong here.

[vongohren]

@epoberezkin typescript does what I intend to do :) They give me warning that something is required, but lots of other things can be in the same object.

So im happy with the TS implementation, but would love to be able to validate this as well somehow?
I did think additionalProperties might work?

And it is enforcing typez to be the right value:

[epoberezkin]

What I meant is that if you add types: 5 in the object typescript would probably be happy about it.

In general, even though JavaScript and TypeScript allow mixing records and dictionaries in the same object, it's usually better to keep them separate, limiting records to known properties only (without any unknown additional properties).

If the intention is to allow additional properties in JSON, it's ok, but you don't have to declare them in the type - you can just add additionalProperties: true in the schema (for forward compatibility), but you only need them in the type if your code is adding such properties, and your code shouldn't really be doing that.

[vongohren]

@epoberezkin thanks for quick reply! But I had updated my message with that specific worry you had. It catches that as well. But thanks for the feedback.

I will have to think about it. Will close tomorrow!