Update a single element in an array in MongoDB using NodeJS without knowing the index [duplicate]

Question

In my database I have something that looks like this:

 "_id" : ObjectId("5c0d9d54df58cb2fdc7f735a"),
"notificationMessages" : [ 
    {
        "message" : "Some message 1",
        "showNotification" : true,
        "projectId" : "5c0e40683500fe72a8e3ce8f"
    }, 
    {
        "message" : "Some message 2",
        "showNotification" : true,
        "projectId" : "5c0e6e113500fe72a8e3ce90"
    }
],

I want to update the "showNotification" to false when clicked on the concrete message on my client-side. To do this, I'm sending the index of what array I clicked on from the client-side to the nodejs server and I'm trying to use that result as the index for my update query, but it doesn't work. First I tried doing this:

  exports.delete_notification = async function(req,res) {

  let  arrayIndex = req.body.index;
console.log("This is the arrayIndex")
console.log(arrayIndex)


await User.update(
  {_id: req.session.userId},
  {$set: {'notificationMessages.' + arrayIndex + '.showNotification': false }}
)


res.status(200).json("done")

}

However, It seems as tho plusses are not allowed inside a update query: (disregard the console.log(theString), theString doesn't exist I know, but that isn't the problem.)

So instead I tried doing this query

await User.update(
  {_id: req.session.userId},
  {$set: {'notificationMessages.arrayIndex.showNotification': false }}
)

This however results in following error:

(node:20656) UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 1): MongoError: Cannot create field 'arrayIndex' in element {notificationMessages: [ { message: (....)

Anyone who can help me on how to properly update with a index that's recieved from the client-side?

See linked dupe. {$set: {['notificationMessages.' + arrayIndex + '.showNotification']: false }} — JohnnyHK
– JohnnyHK, Commented Dec 13, 2018 at 0:03
Thank you. Don't know how I didn't find that thread, but it solved my question — Thomas
– Thomas, Commented Dec 13, 2018 at 9:14

mralanlee · Accepted Answer · 2018-12-12 23:53:14Z

1

Array Indexes are accessible by bracket notation.

await User.update(
  {_id: req.session.userId},
  {$set: { notificationMessages[arrayIndex].showNotification: false }}
)

Try doing it without the single quote. If it doesn't work you can alternatively try to template string it like the following:

await User.update(
  {_id: req.session.userId},
  {$set: { `notificationMessages[${arrayIndex}].showNotification`: false }}
)

answered Dec 12, 2018 at 23:53

mralanlee

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