Question 240184 in Mongodb Question posted in
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Mongodb – $project / $addField with field name (path) contains . or $

I am having issues with projecting some fields with mongodb $project

my colection has the following datas

[{num:"SI-0101",mob:6289141515},...]

and my $project query

[{
  $project: {
    "Id No.": "$num",
    "Mobile No.": "$mob" // note on that ., i need it in o/p
  }
}]

When I execute this, it raise error says Field path not ends with .

How I resolve this ?

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2

Answers


  1. 0

    MongoDb does not support keys that end with a dot (.). You can edit it in your code after the query. For example:

    const userRes = await userModel.findOne({num:"SI-0101"}, {num: 1, mob: 1}).lean();
return {'Id No.': userRes.num, 'Mobile No.': userRes.mob}
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  2. 0

    You can use $setField to achieve such behaviour if you are using MongoDB v5.0+

    db.collection.aggregate([
  {
    $replaceWith: {
      $setField: {
        field: "Id No.",
        input: "$$ROOT",
        value: "$num"
      }
    }
  },
  {
    $replaceWith: {
      $setField: {
        field: "Mobile No.",
        input: "$$ROOT",
        value: "$mob"
      }
    }
  },
  {
    $unset: [
      "num",
      "mob"
    ]
  }
])

    Mongo Playground

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