Chapter 4: Advanced CRUD Operations- Lab: $expr

HI Team,

Not able to proceed with below question:

How many companies in the sample_training.companies collection have the same permalink as their twitter_username?

I have executed the below script on IDE

db.companies.find({
$expr: { $eq: ["$permalink", “$twitter_username”] }
}).count()

I received 1302 as result with sample database.

But application is not accepting .

We have similar issue " Chapter 3: Creating and Manipulating Documents-### Quiz: Updating Documents in the shell" . as per question, we have a collection for Wolf . but we have an options for cats. There is no proper answer for it.

Please advice for it.

The sample document with “pet”:“wolf” is simply an example to show that

each document has the following structure and fields

The exact document that will be updated is irrelevant to the question.

And as for

Your query which looks appropriate, but I get a different count as yours. Perhaps your data set has been altered. It might be a good idea to terminate your current cluster and create a new one so start afresh with appropriate data.