Mongo DB find query with Regex not returning expected output

Question

Below is my query which return result from database. I am using 3.2.22 mongo version

db.courses.find({_id:"edX-NYIF+CR.5x"});

Now I want fetch record of course Id which will be in lower case so I used below query it seems working fine if i use alpha character but not getting result for following course Id.

db.getCollection('courses').find({"_Id": { $regex : "edX-NYIF+CR.5x$" , $options: 'i'}})

score 2 · Accepted Answer · answered Jun 06 '19 at 17:46

2

Regex expression string needs to be escaped

db.getCollection('courses').find({"courseId": { $regex : "edX\\-NYIF\\+CR\\.5x$" , $options: 'i'}})

MongoPlayground

answered Jun 06 '19 at 17:46

Anton

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score 0 · Answer 2 · answered Jun 06 '19 at 14:27

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At first sight, your query looks OK... but I don't think this is going to work as you expected, because of the format of your ID.

The string "edX-NYIF+CR.5x" contains characters that have specific meanings for regexes, such as . and +, and perhaps some other IDs contain others. You should escape these first.

Looking at another SO question, there's a simple way to escape regex-sensitive characters:

string.replace(/[.*+?^${}()|[\]\\]/g, '\\$&')

So escape your ID string and then use it in your query.

Here's a handy reference for special characters inside regular expressions, should you need it.

answered Jun 06 '19 at 14:27

SolarBear

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could you help me with query .? – Tejal Jun 06 '19 at 14:32
Wait: are you querying for the `_id` field or the `courseId` field? Your queries do not use the same field for querying. Was that a mistake in your question? – SolarBear Jun 06 '19 at 15:19

Mongo DB find query with Regex not returning expected output

2 Answers2