Change value to undefined mongoose findOneAndUpdate

Question

I'm trying to update a schema values based on user input.

My schema is:

({ name: { type: String, required: true, }, color: { type: String, }, createdAt: { type: Date, default: Date.now, }, });

The name field is required however the color field is optional. So, supposing the user created a document:

{ "name": "Blue", "color": "#20387d" }

he can then edit the same document where he doesn't provide the color value:

 { "name": "Blue" }

My code for update is:

 const { name, color} = req.body; const document = await Model.findOneAndUpdate( { _id: req.params.id, }, { $set: { name, color }}, { new: true } );

This should update color value to undefined in my MongoDB. However, the color remains same as provided initially whereas the name updates. I want the color to change to undefined if its not provided by the user. How do I do that?

what happens when you pass { $set: { name, color: undefined } in query, does it works now ? — bogdanoff
– bogdanoff, Commented Jul 22, 2022 at 16:11
if you really want to remove it, you have to use $unset. But I prefer using null as value instead of undefined. — bogdanoff
– bogdanoff, Commented Jul 22, 2022 at 16:25
But to $unset the value, I will have to first check if the color value exists or not. I thought there would be a way to do it directly with findOneAndUpdate function — SunAns
– SunAns, Commented Jul 22, 2022 at 16:31

Bill Dagg · Accepted Answer · 2023-05-31 19:18:26Z

2

As @bogdanoff indicated in the comments, you can set the value to null, not undefined.

answered May 31, 2023 at 19:18

Bill Dagg

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bogdanoff · Accepted Answer · 2022-07-23 01:54:05Z

Since you don't want use $unset or setting that value to something else, that leaves only one way.

Use findById/findOne to fetch that Doc then modify its content then save it.

 const document = await Model.findById( req.params.id, { name: 1, color: 1 } ); //.. document.color = req.body.color || undefined //.. await document.save()

above code works because mongoose detects change.

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