An example of a morph that generates interfaces from classes.

example-morph.ts

import { Project } from 'ts-morph'

  /**
   * Get the scope of the NestJS project by specifying its tsconfig.
   */
  const project = new Project({
    tsConfigFilePath: 'tsconfig.json',
  })

  /**
   * Get the types pkg file you created to house the new types.
   */
  const typePkgFile = project.getSourceFile('./types-pkg/index.ts')
  if (!typePkgFile) throw Error('Cannot find type package file.')

  /**
   * Extract interfaces from class models and add to the types pkg.
   */
  const modelFiles = project.getSourceFiles(['./src/**/*.model.ts'])

  modelFiles.forEach((file) => {
    const classes = file.getClasses()
    classes?.forEach((c) => {
      const i = c.extractInterface()
      typePkgFile.addInterface(i)

      const newInterface = typePkgFile.getInterface(i.name)
      if (!newInterface) return

      newInterface.setIsExported(true)
    })
  })
  
  project.save()