Model.syncIndexes() fails with `MongoError: a collection 'dbname.tablename' already exists`

Do you want to request a feature or report a bug? bug

What is the current behavior? run Model.syncIndexes(); for existing model.

If the current behavior is a bug, please provide the steps to reproduce.

https://gist.github.com/rideddy84/a189d839cbef093f719a0e850f2c5ff7.js

{
  "compilerOptions": {
    "allowSyntheticDefaultImports": true,
    "esModuleInterop": true,
    "lib": ["esnext"],
    "module": "commonjs",
    "moduleResolution": "node",
    "noUnusedLocals": true,
    "noUnusedParameters": true,
    "outDir": "lib",
    "sourceMap": true,
    "target": "esnext"
  },
  "exclude": ["node_modules"]
}

What is the expected behavior? Indexes are created if they weren’t before.

What are the versions of Node.js, Mongoose and MongoDB you are using? Note that “latest” is not a version. “mongoose”: “5.13.2” Node.js v14.17.0

[Spown]

What do you mean by sync indexes for existing collections? Do you want to create an index on every collection?

I think he, just like me, wants to force reindex on every app init. Because out-of-the-box, if the raw DB tables have indexes defined, mongoose ignores index settings from mongoose.model(), so you either need to drop indexes before registering a model (this is what I was doing a couple years ago) or run .syncIndexes(). Regardless whether they were changed or not this insures that raw DB and model settings match indexes-wise.

[IslandRhythms]

const mongoose = require('mongoose');
const {Schema} = mongoose;


const schema = new Schema({ name: { type: String, unique: true } });
const Customer = mongoose.model('Customer', schema);

async function test() {
    await mongoose.connect('mongodb://localhost:27017/test', {
        useNewUrlParser: true,
        useUnifiedTopology: true
      });
    await mongoose.connection.dropDatabase();
    await Customer.collection.createIndex({ age: 1 }); // Index is not in schema

    Customer.collection.getIndexes().then(indexes => {
        console.log(indexes);
    })
    // Will drop the 'age' index and create an index on `name`
    await Customer.syncIndexes();

    Customer.collection.getIndexes().then(indexes => {
        console.log(indexes);
    })
}

test();

The above code runs fine. Copy it and change it to demonstrate your issue. @rideddy84