Schema $ref to standalone type results in generation of type in generated typescript interface.

[AndyDBell]

I am not sure whether this is a configuration problem, expected behaviour or a bug but...

I declare a json schema file id.schema.json containing:

{
  "title": "TId",
  "type": "string"
}

Running json-schema-to-typescript.compileFromFile( id.schema.json ) generates:

export type TId = string

I create a second json schema file example.schema.json referencing id.schema.json and containing:

{
  "title": "IExample",
  "type": "object",
  "properties": {
    "id": {
      "$ref": "id.schema.json"
    },
    "name": {
      "type": "string"
    }
  },
  "required":[
    "id"
  ],
  "additionalProperties": false
}

Running json-schema-to-typescript.compileFromFile( example.schema.json ) generates:

export type TId = string

export interface IExample {
  id: TId
  name?: string
}

Here the type TId is generated in addition to the interface IExample. i.e. TId is defined twice, once in each file.

This makes it impossible to use the generated code in a typescript program with out manual editing to remove the second definition of TId.

[bcherny]

Hi @AndyDBell! You can avoid declaring externally referenced types by setting the declareExternallyReferenced option to false. In the future, you'll be able to use batch mode to generate a set of typings at once with automatic deduping.

Let me know if that works for your use case!

[AndyDBell]

Hi Boris,

Thanks for your response.

I have tried setting declareExternallyReferenced to false in the compileFromFile options but the output did not change!

This is my options object:

  const options: any = {
    cwd: './src/models/jsonschema',
    declareExternallyReferenced: false,
    unreachableDefinitions: false,
    style: {
      semi: false,
      singleQuote: true,
    }
  }

The generated typescript is the same as with declareExternallyReferenced set to true.

[bcherny]

Hmm could you upload a self-contained repro case? This does seem like a bug. In the meantime, generating multiple copies of a type should be fine - TypeScript will merge them for you as best it can.

[AndyDBell]

Zipped self contained repro code shared on onedrive at https://1drv.ms/u/s!ArpiIInQBexRhZY9b-gSPf3z1QxXTQ.
Note - included everything including node_modules, dist etc. Editor is vscode.

[bcherny]

Thanks for the repro case @AndyDBell.

What's happening here is that declareExternallyReferenced isn't working as expected for primitive types (as opposed to interfaces).

I maintain this project in my spare time, and won't have time to fix this soon. Sorry about the inconvenience. Also, contributions are welcome!

In the meantime, you have 3 options for workarounds: (1) remove the type alias from your JSON-Schema, (2) manually edit the outputted file, or (3) combine your schemas into one.