Convert string to double if it is not ""

Working with Data
,
#1

Hi, I have collection like {“stringdouble”: “26.58”, “stringouble”: “36.58”, “stringdouble”: “”}
I need to convert stringdouble datatype to float in aggregate pipeline whose result looks like {“stringdouble”: 26.58, “stringdouble”: 36.58, "stringdouble: 0}, if it has “”, then it should be 0.

#2

If you can, insert the data with the correct type in the first place.

Using $toDouble on "" would error so you have to use $convert with the onError option:

db.baz.aggregate([
{$set:{
  n:{$convert: {input:'$stringdouble',to:'double',onError:0}}}},
{$project:{_id:0}}
])
[
  { stringdouble: '26.58', n: 26.58 },
  { stringdouble: '36.58', n: 36.58 },
  { stringdouble: '', n: 0 }
]