Update Field in MongoDb of object to array of objects - command line

Question

I have a collection in MongoDB called Results

I have a field in the collection called Positions

"Positions": {
    "X": "1",
    "Y": "2"
}

I want to update this field to be an array of positions

 "Positions": [{
        "X": "1",
        "Y": "2"}, {X:"100", Y:"200"}]

I want to do this using the command line, is it possible? I have tried the following

use MyMongoDb

followed by

db.getCollection("Results").find( { "Positions" : { $type : 2 } } ).snapshot().forEach( function (x) {x.Positions = [ Positions ];db.jobs.save(x);});

I get an exception

QUERY    [js] uncaught exception: TypeError: db.getCollection(...).find(...).snapshot is not a function :
@(shell):1:1

Alexey Victorov · Accepted Answer · 2020-10-01 18:11:19Z

2

snapshot is not a function of cursor says error stack... And it is right.

Anyway I propose you to use the following code

db.getCollection("Results")
   .find( { "Positions" : { $type : 2 } } )
   .forEach( function(x) {
      x.Positions = [ x.Positions ];
      db.getCollection("Results").save(x);
   });

Please note that I have replaced x.Positions = [ Positions ] with x.Positions = [ x.Positions ] as Positions variable is not declared. And also db.jobs.save(x) with db.getCollection("Results").save(x) as I understood you wanted to update same collection.

I also would recommend to migrate depreciated save method to update or replaceOne.

answered Oct 1, 2020 at 18:11

Alexey Victorov

4332 silver badges10 bronze badges

Sign up to request clarification or add additional context in comments.

7 Comments

MicroMan Over a year ago

thanks for your feedback, the error is gone and the code execute but it just proceeds to a new line with the ">" character and the data did not change?

Alexey Victorov Over a year ago

1. Check if "Results" collection has documents for specified selector. For instance: db.getCollection("Results").find( { "Positions" : { $type : 2 } } ).count() should return anything greater than 0

Alexey Victorov Over a year ago

2. If you really don't have _id field on document replace forEach function with:

function(x) { db.getCollection("Results").remove(x); x.Positions = [ x.Positions ]; db.getCollection("Results").insert(x);}

MicroMan Over a year ago

the query returns 0? why is that?

MicroMan Over a year ago

There is a a _id field defined in the collection "_id": { "$oid": "5e95b70fb54af5cb6ce49793" },

|

Collectives™ on Stack Overflow

Update Field in MongoDb of object to array of objects - command line

1 Answer 1

7 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

7 Comments

Your Answer

Sign up or log in

Post as a guest

Related