Exported variable 'Todo' has or is using 'IModelType' ... but cannot be named. in Typescript

[mikecann]

A simple example taken from the MST docs:

import { types } from "mobx-state-tree"

export const Todo = types.model({
    title: types.string
})
.named("Todo")
.actions(self => ({
    setTitle(v: string) {
        self.title = v
    }
}))

export type ITodo = typeof Todo.Type

With tsconfig.json:

{
  "compilerOptions": {
    "outDir": "./dist",
    "module": "commonjs",
    "target": "es5",
    "lib": ["es6", "dom"],
    "declaration": true,
    "jsx": "react",
    "moduleResolution": "node",
    "experimentalDecorators": true,
    "forceConsistentCasingInFileNames": true,
    "noImplicitReturns": true,
    "noImplicitThis": true,
    "noImplicitAny": true,
    "strictNullChecks": true,
    "suppressImplicitAnyIndexErrors": true,
    "noUnusedLocals": true
  },
  "include": [
    "src/**/*"
  ],
  "exclude": [
    "node_modules",
    "dist" 
  ]
}

Gives the following compiler error:

 error TS4023: Exported variable 'Todo' has or is using name 'IModelType' from external module "C:/dev/me/markd/node_modules/mobx-state-tree/dist/types/complex-types/object" but cannot be named.

Unfortunately it looks like this is not a MST problem and is instead a Typescript issue:

microsoft/TypeScript#5938

Until this is fixed in Typescript or MST it renders MST unusable for my use case in Typescript :(

[mikecann]

If you import it at the top:

import { types, IModelType } from "mobx-state-tree"

With my given compiler args you then get:

error TS6133: 'IModelType' is declared but never used.

[mikecann]

Okay so you can get around it if you do this nastyness:

import { types, IModelType } from "mobx-state-tree"

export type __IModelType = IModelType<any,any>;

export const Todo = types.model({
    title: types.string
})
.named("Todo")
.actions(self => ({
    setTitle(v: string) {
        self.title = v
    }
}))

export type ITodo = typeof Todo.Type

[mattiamanzati]

Yep, Thats a known typescript behaviour with interfaces :)
Closimg for now

[mikecann]

@mattiamanzati Okay, perhaps put it in the docs, in the Typescript section to make people aware of the issue?

[mattiamanzati]

Yeah, would make sense :)
Are you up to make a PR for that?

[mikecann]

Sure, ill do it now

[mattiamanzati]

Great! Thanks a lot! :)

[mweststrate]

does "export { imodeltype} from mobx-state-tree" help?

…

On vr 6 okt. 2017 07:22 Mattia Manzati ***@***.***> wrote: Great! Thanks a lot! :) — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#426 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/ABvGhOMLQ426mRXGjTf_MQTvcNpRm2Jiks5spbkrgaJpZM4Pv4tf> .

[mikecann]

@mweststrate no, I tried that already, you get the same error

[oadeojo]

Is there a work around for this? I am trying to make my MST store an exportable library but I get

error TS4023: Exported variable 'User' has or is using name 'IModelType'

when I try to compile it.