TS1205 [ERROR]: Re-exporting a type when the '--isolatedModules' flag is provided requires using 'export type'

Hey there, it has taken me already 3 weeks I’m trying to fix this and I didn’t found a solution. In my code source, I created a file called deps.ts at my project root and I export denodb module (export { Database } from "https://deno.land/x/denodb@v1.0.12/mod.ts";). When I run my server, I got many errors that I need help. Theses are errors `error: TS1205 [ERROR]: Re-exporting a type when the ‘–isolatedModules’ flag is provided requires using ‘export type’. export { LogLevels, LevelName } from “./levels.ts”; ~~~~~~~~~ at https://deno.land/std@0.63.0/log/mod.ts:13:21

TS1205 [ERROR]: Re-exporting a type when the ‘–isolatedModules’ flag is provided requires using ‘export type’. Deferred,

  at https://deno.land/x/mysql@v2.5.0/deps.ts:3:3

TS1205 [ERROR]: Re-exporting a type when the '--isolatedModules' flag is provided requires using 'export type'.
export { Client, ClientConfig } from "./src/client.ts";
               ~~~~~~~~~~~~
  at https://deno.land/x/mysql@v2.5.0/mod.ts:1:18

TS1205 [ERROR]: Re-exporting a type when the '--isolatedModules' flag is provided requires using 'export type'.
export { ObjectId, UpdateOptions } from "./ts/types.ts";
                 ~~~~~~~~~~~~~
  at https://raw.githubusercontent.com/eveningkid/deno_mongo/master/mod.ts:5:20

TS1205 [ERROR]: Re-exporting a type when the '--isolatedModules' flag is provided requires using 'export type'.
ClientOptions as MongoDBClientOptions,

at https://deno.land/x/denodb@v1.0.12/unstable_deps.ts:11:3

Found 5 errors.`

Anyone got the same ? How to fix them ? I use Deno version 1.5.0, typescript 4.0.3

[boyarzun]

I had the same problem (-isolatedModules…), this is what helped me to understand:

Type-Only Imports and Export https://www.typescriptlang.org/docs/handbook/release-notes/typescript-3-8.html#type-only-imports-and-exports (…if you’ve hit issues under --isolatedModules, TypeScript’s transpileModule API, or Babel, this feature might be relevant…)

And here is another example of how I used export type

// deps.ts

import {
    Application,
    Router,
    RouterContext
} from 'https://deno.land/x/oak/mod.ts';

export {
    Application,
    Router,
};

export type { RouterContext };

[stillalivx]

It seems the issue comes from this: https://deno.land/posts/v1.5#stricter-type-checks-in-stable Luckily, you can override this creating a tsconfig.json in you project with this content:

{
  "compilerOptions": {
    "isolatedModules": false
  }
}

Then, execute your code like this:

deno run -c tsconfig.json --allow-net --allow-read --unstable server.ts

Let me know if this works for you! We have to wait for the others deps update their code. This is a temporary fix.