MongoDB/mongoose: query array field elements to match a part of a string

Question

GIVEN

a searchString "*** test text before string *** john doe | test string after string"

AND

a MongoDB document:

{
  "name": "John Doe",
  "matchingWords": [
    "john doe", "another string"
  ]
}

I WANT TO query for any documents that have at least 1 element in the matchingWords field (string[]) that is found in the searchString. !! The elements in matchingWords might contains spaces.

Expected result: the mongoDB document above is found because element "john doe" is found in the searchString.

Problem

The code below is only working when matchingWords elements do not contain spaces... And I cannot find a solution to fulfill my requirement. So please help me :-)

private async findByMatchingWords(searchString: string): Promise<boolean> {
if (!searchString) return false;

const lowerCaseSearchStrings: string[] = searchString.toLowerCase().split(' ');
const results = await paymentPartyModel
  .find<IPaymentParty>({
    matchingWords: {
      $exists: true,
      $not: { $size: 0 }, // Check if array exists and is not empty
      $in: lowerCaseSearchStrings,
    },
  })
  .lean();

if (!results || results.length === 0) {
  return false;
} else if (results.length === 1) {
  this.info = results[0];
  return true;
} else {
  // 2 or more matches found...
  Todo('What to do when more than one payment party matches the search?');
  return false;
}

}

Answer 1

Use $indexOfCP to check for the existence of the matchingWords within the substring. If the matchingWord is not inside, it would return -1. $map this result to an array of boolean from matchingWords array. Use $anyElementTrue to check for any words that are within the search string.

db.collection.find({
  $expr: {
    $anyElementTrue: {
      "$let": {
        "vars": {
          "searchString": "*** test text before string *** john doe | test string after string"
        },
        "in": {
          "$map": {
            "input": "$matchingWords",
            "as": "mw",
            "in": {
              "$ne": [
                -1,
                {
                  "$indexOfCP": [
                    "$$searchString",
                    "$$mw"
                  ]
                }
              ]
            }
          }
        }
      }
    }
  }
})

Mongo Playground