Better Mongoose RootQuerySelector Type

This proposition is currently still in development, please check the TODO List

A proposition for a change of the RootQuerySelector type to include nested paths and remove the any index signature.

How to Use

Simply add the following line to your tsconfig.json file:

{
  "compilerOptions": {
    // ...
    "types": ["node_modules/better-mongoose-filter-query-type"]
  }
}

Stability & Performance

Unit Testing

Performance Charts

Motivation

As of today, the RootQuerySelector type has the following definition:

type RootQuerySelector<T> = {
  /** @see https://www.mongodb.com/docs/manual/reference/operator/query/and/#op._S_and */
  $and?: Array<FilterQuery<T>>;
  // ...
  // we could not find a proper TypeScript generic to support nested queries e.g. 'user.friends.name'
  // this will mark all unrecognized properties as any (including nested queries)
  [key: string]: any;
};

Notice the [key: string]: any and the comment above it. In short, this means that Mongoose could not find a type that receives an object and generates all its paths, including nested paths:

interface Input {
  field: string;
  nested: {
    anotherField: number;
  }
}

interface ExpectedOutput extends RootQuerySelector<Input> {
  field: Condition<string>;
  // Can't compute these fields:
  nested: Condition<{ anotherField: number }>;
  'nested.anotherField': Condition<number>;
}

Instead, Mongoose resorted to declaring the fields they can (root fields such as $and, $or, etc. and the direct fields of the input object) and allowing for any other field to exist with the any type. This gives the freedom for the user to add nested paths without TypeScript complaining, but comrpomises on type-safety.

I noticed this lack of type-safety when I had a typo in a nested path or had a misspelled condition, both of which caused some bugs that were rather hard to find. I decided to take upon myself the challenge of generating these nested paths.