How to ignore undefined values in Mongoose aggregate match?

[somersby10ml]

I have a question regarding Typescript and Mongoose.

I need to use the aggregate function in a specific scenario. In the match part of the aggregate, I tried using { a: 11, b: undefined }, but it seems to search for a == 11 and b == undefined. However, what I want is to ignore the fields with undefined values.

I'd like to find a good approach to achieve this without dynamically creating the query. For example, let's say I have 5 fields in the database. I want to perform a search based on user input. Consider the following:

const a = 'aa';
const b = 'bb'; 
const c = undefined;
const d = '11';
const e = undefined;

In this case, I want to ignore the undefined fields and have the query result in a == 'aa' and b == 'bb' and d == '11'.

When using Prisma, I could do something like db.user.findMany({ a, b, c, d, e, ... }); and if any field was undefined, it would be ignored and filtered accordingly.

Is there a similar functionality, option, or library available in Mongoose to achieve this?

[vkarpov15]

Unfortunately Mongoose doesn't export anything quite like this. Your best bet would be to write an omitUndefined() helper:

function omitUndefined(val) {
  const keys = Object.keys(val);
  for (let i = 0, len = keys.length; i < len; ++i) {
    (val[keys[i]] === void 0) && delete val[keys[i]];
  }
}

We should export an omitUndefined helper for this sort of use case.