3.6 Change Streams updateDescription.updatedFields

[Kevin Fairclough]

Change streams, update event.

Is the format for updateDescription.updatedFields the same as the format you would provide to a $set operation?

i.e. could i take the document and update a copy of the document by using  { $set: updateDescription.updatedFields}

Similarly with the updateDescription.removedFields although i noticed that is an array so I guess I'll have to construct $unset manually.

Thanks

Kevin

[Wan Bachtiar]

Is the format for updateDescription.updatedFields the same as the format you would provide to a $set operation?

Hi Kevin,

The format would be the same as what $set operation would accept. For example if you have a database update operation as below:

db.collection.update({"_id":101}, {"$set":{"x":{"a":1, "b":1, "c":1}}})

the value of document output for the change event would be:

{   '_id': {   '_data': '',
               '_typeBits': b'\x01'},
    'documentKey': {'_id': 101.0},
    'fullDocument': {   '_id': 101.0,
                        'x': {'a': 1.0, 'b': 1.0, 'c': 1.0}},
    'ns': {'coll': 'collection', 'db': 'database'},
    'operationType': 'update',
    'updateDescription': {   'removedFields': [],
                             'updatedFields': {   'x': {   'a': 1.0,
                                                           'b': 1.0,
                                                           'c': 1.0}}}}

See also Change Streams and Change Stream Examples

Regards,
Wan.

​

[Kevin Fairclough]

Thanks

Wan

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