CODEWITHSUNDEEP
mongodbexpressmongooseexec
CodeOnTheWall
CodeOnTheWall

Reputation: 41

what is exec() method doing here?

When creating a new user, im checking for a duplicate first via:

  const duplicate = await User.findOne({ username }).lean().exec();

I am confused as to why the coding tutorial im doing attaches the exec method. From what i read, this checks for a match in the string and will return any matches in an array. So on a post req, id get a username, findOne (i believe) will already match the req.body.username to a username inside my User schema/DB, hence i dont understand why the person running the tutorial also adds the .exec method. im sure something is flying over my head.

Tried reading mdn docs on exec method

Upvotes: 0

Views: 1571

Answers (1)

Joe
Joe

Reputation: 28336

In that line of code:

Model.findOne creates and returns a query object, which can be further acted on.

The lean method modifies that query, and returns the modified object.

The exec method executes the query asynchronously and returns a promise.

await waits for the promise to resolve, and returns the final value, which is then assigned to the duplicate variable.

Upvotes: 1

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