无法像这样交叉导入猫鼬模式

Question

我使用打字稿开发了nodejs项目。而且我不明白为什么以下代码无法正常工作。 这里我们有A.ts，B.ts和index.ts。

// A.ts
import * as mongoose from 'mongoose';
import {Bmodel} from './B';

const schema = new mongoose.Schema({
    name: {
        type: String,
        required: true
    },

    B: [{
    type : mongoose.Types.ObjectId,
    ref : Bmodel.modelName
    }]
});

export const Amodel = mongoose.model('A',schema);

// B.ts
import * as mongoose from 'mongoose';
import {Amodel} from './A';
const schema = new mongoose.Schema({
    name: {
        type: String,
        required: true
    },

    A: [{
    type : mongoose.Types.ObjectId,
    ref : Amodel.modelName
    }]
})

export const Bmodel = mongoose.model('B',schema);

import * as mongoose from 'mongoose';
import "./A";
import './B';

mongoose.connect("mongodb://localhost/movies")
.then(()=>{
    console.log("db connected!");
})
.catch((err)=>{
    console.log(err);
})

在package.json中

{
  "name": "testlab",
  "version": "1.0.0",
  "main": "index.js",
  "license": "MIT",
  "devDependencies": {
    "@types/mongoose": "^5.5.34"
  },
  "dependencies": {
    "mongoose": "^5.8.2"
  }
}

通过命令“ tsc index.ts”编译上面的代码后，我们得到了js文件。运行“ node index.js”时，它将引发以下错误：

/mnt/e/Project/Express-blueprint-ts/testlab/B.js:12
            ref: A_1.Amodel.modelName
                            ^

TypeError: Cannot read property 'modelName' of undefined
    at Object.<anonymous> (/mnt/e/Project/Express-blueprint-ts/testlab/B.js:12:29)
    at Module._compile (module.js:652:30)
    at Object.Module._extensions..js (module.js:663:10)
    at Module.load (module.js:565:32)
    at tryModuleLoad (module.js:505:12)
    at Function.Module._load (module.js:497:3)
    at Module.require (module.js:596:17)
    at require (internal/module.js:11:18)
    at Object.<anonymous> (/mnt/e/Project/Express-blueprint-ts/testlab/A.js:4:11)
    at Module._compile (module.js:652:30)
    at Object.Module._extensions..js (module.js:663:10)
    at Module.load (module.js:565:32)
    at tryModuleLoad (module.js:505:12)
    at Function.Module._load (module.js:497:3)
    at Module.require (module.js:596:17)
    at require (internal/module.js:11:18)