MongoDB: convert existing json string to json object

Question

I am trying to convert an existing json string field to json array/object as I have recently moved data from mysql to mongodb.

{
  "_id": {
    "$oid": "63f241012a9551202e909257"
  },
  "title": "Jumanji: Welcome To The Jungle",
  "description": "...",
  ...
  "info": "[{\"year\": \"2017\", ... },{\"year\": \"2019\", ... }]",
  ...
}

I need this to be

{
  "_id": {
    "$oid": "63f241012a9551202e909257"
  },
  "title": "Jumanji: Welcome To The Jungle",
  "description": "...",
  ...
  "info": [{
    "year": 2017, 
    ... 
  }, {
    "year": 2019, 
    ... 
  }],
  ...
}

Answer 1

Here's one way to convert your JSON string by letting Javascript parse it.

db.movies.update({},
[
  {
    "$set": {
      "info": {
        "$function": {
          "lang": "js",
          "args": ["$info"],
          "body": "function(infoStr) {return JSON.parse(infoStr)}"
        }
      }
    }
  }
],
{
  "multi": true
})

Try it on mongoplayground.net.

Answer 2

With reference to @rickhg12hs solution, below is another way to perform the same task.

db.movies.updateMany({}, [{
  $set: {
    info: {
      $function: {
        lang: "js",
        args: ["$info"],
        body: "function(infoStr) { return JSON.parse(infoStr); }"
      }
    }
  }
}]);

Also, please keep that in mind that the arrow function syntax is not supported in this scenario. So, always use function notations to perform such operations.