CODEWITHSUNDEEP
mongodb
JVG
JVG

Reputation: 21150

MongoDB - Using regex wildcards for search that properly filter results

I have a Mongo search set up that goes through my entries based on numerous criteria.

Currently the easiest way (I know it's not performance-friendly due to using wildcards, but I can't figure out a better way to do this due to case insensitivity and users not putting in whole words) is to use regex wildcards in the search. The search ends up looking like this:

{ gender: /Womens/i, designer: /Voodoo Girl/i } // Should return ~200 results
{ gender: /Mens/i, designer: /Voodoo Girl/i } // Should return 0 results

In the example above, both searches are returning ~200 results ("Voodoo Girl" is a womenswear label and all corresponding entries have a gender: "Womens" field.). Bizarrely, when I do other searches, like:

{ designer: /Voodoo Girl/i, store: /Store XYZ/i } // should return 0 results

I get the correct number of results (0). Is this an order thing? How can I ensure that my search only returns results that match all of my wildcarded queries?

For reference, the queries are being made in nodeJS through a simple db.products.find({criteria}) lookup.

Upvotes: 0

Views: 1350

Answers (1)

Chris Heald
Chris Heald

Reputation: 62648

To answer the aside real fast, something like ElasticSearch is a wonderful way to get more powerful, performant searching capabilities in your app.

Now, the reason that your searches are returning results is that "mens" is a substring of "womens"! You probably want either /^Mens/i and /^Womens/i (if Mens starts the gender field), or /\bMens\b/ if it can appear in the middle of the field. The first form will only match the given field from the beginning of the string, while the second form looks for the given word surrounded by word boundaries (that is, not as a substring of another word).

If you can use the /^Mens/ form (note the lack of the /i), it's advisable, as anchored case-sensitive regex queries can use indexes, while other regex forms cannot.

$regex can only use an index efficiently when the regular expression has an anchor for the beginning (i.e. ^) of a string and is a case-sensitive match.

Upvotes: 3

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