Template Literal String Types are converted to an array schema instead of a string

[ssc-hrep3]

Template Literal String Types are converted to an array schema. They should, however, be converted to strings with a pattern matching the template literal (or at least to a regular string).

Here is an example of a template literal:

export const Test = `${number}`;

This type is then generated to:

{
  "type": "array",
  "items": {
    "type": "string"
  }
}

It should, however, at least be converted to this instead:

{
  "type": "string"
}

Even better would be if the template literal string is converted to a valid pattern. But this might be rather complex (joining regular expressions from types used within the template literal with the static string).

{
  "pattern": "^-?[1-9]\d*(?:\.\d+)?$"
  "type": "string"
}

A temporary workaround is to use the JSDoc annotation @type string, but unfortunately this does not work everywhere (i.e. when the template literal types are being used directly in arrays) due to another bug (see #425).

Version: 0.50.1
Schema Generation Settings:

{
  ref: false,
  required: true,
  noExtraProps: true,
  validationKeywords: ['errorMessage'],
  titles: true,
  uniqueNames: true,
  rejectDateType: true
}

[olafur-palsson]

Related is using a template literal inside a template literal and getting 'TemplateLiteral' only refers to a type, but is being used as a value here. can be fixed by updating.

[derekslarson]

Facing the same issue in 0.51.0

[slhck]

@YousefED Any idea on how to solve this? Still getting this.

Note that as a workaround you may use ts-json-schema-generator:

export type Test = {
    foo: `${number}x${number}`;
}

Then ts-json-schema-generator --path test.ts returns:

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