Update an index of MongoDB array dynamically

Question

I want to update any index of FirstCol array dynamically in Nodejs. How do I go about doing that in this collection.

   {
     "TableId": "0",
     "FirstCol": [
        "Have high energy ",
        "Talk more than listen "
     ]
    }

I know I can update a specific array index using the dot operator. For eg:

 db.testcol.update(
    { "TableId": "0" },
    { $set:
      {
        "FirstCol.1": "rain gear"
      }
     }
    )

But what if I did not know that I have to edit index 1 of array FirstCol. How to frame the update query in order to update the index of the array which is suppose in variable 'editIndex'. Can I do something like:

db.testcol.update(
        { "TableId": "0" },
        { $set:
          {
            "FirstCol.editIndex": "rain gear"
          }
         }
        )

Need your help. Thanks :)

This works db.arr.update({},{ $set: { "arr.0" : 'Your updated text' } }, {many:false}) — Viswanath Lekshmanan
– Viswanath Lekshmanan, Commented Oct 8, 2018 at 12:16

Ashh · Accepted Answer · 2018-10-09 10:55:20Z

4

You can try with ES6 Computed Property Keys method

db.testcol.update(
  { "TableId": "0" },
  { "$set": {
    ["FirstCol." + editIndex]: "rain gear"
  }},
  function(err, res) {
    console.log(err)
    console.log(res)
  }
)

edited Oct 9, 2018 at 10:55

answered Oct 8, 2018 at 12:08

Ashh

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3 Comments

alfheimrShiven Over a year ago

Thanks for the response @Anthony I tried to execute the update query with a callback function like this: db.testcol.update( { "TableId": "0" }, { "$set": { ["FirstCol." + editIndex]: "rain gear" }} ),function(err,res) { if(err) console.log("QUERY was not Successfully") else{ console.log("QUERY Successfully"); res.send('Edited'); } } The control is not going to the callback function at all.

Ashh Over a year ago

Upddated the answer

alfheimrShiven Over a year ago

Thank-you so much @Anthony. This worked. I've marked your answer correct also.

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