how to update mongo db all records in c#

Question

I have mongo db collection which stores the JSON. By mistakenly, one element value was updated wrong in all records of a collection.

How i will update the particular element ?

My json is like

{
status:
   {
     name:"john",
     value: "12345678903333.444"
   }
}

here the value property value should be long field, value will be replaced by

{
status:
   {
     "name":"john",
     "value": 1234567890
  }
} 

value should be trimmed as first 10 character of existing value.

After updating(from @mickl answer),

Converting to Int also got error!

Answer 1

You can use $substr operator with $toDouble to convert string to number and then redirect aggregation results into the same collection using $out (which will basically update all its documents), Try in Mongo shell:

db.col.aggregate([
    {
        $addFields: {
            "status.value": { $toDouble: { $substr: [ "$status.value", 0, 10 ] } }
        }
    },
    {
        $out: "col"
    }
])

Or in C# code:

var addFieldsBody = "{ $addFields: { \"status.value\": { $toDouble: { $substr: [ \"$status.value\", 0, 10 ] } } } }";

Col.Aggregate()
   .AppendStage<BsonDocument>(BsonDocument.Parse(addFieldsBody))
   .Out("col");