在 MongoDB 中查找和更改现有的日期字段格式

Question

I've looked into several similar questions but none seem to be what I need, aside from looking complicated. Here's the scenario: I have a messy collection with multiple "date" fields, with names I already know (eg "dateTime", "FirstDate", "Status.date"...).

For each of them, I would like to:

1. Query those which are not in 'dd/mm/YYYY' or 'YYYY-mm-dd' format (for instance there might be fields with random numbers as date such as '534432' or '0', or empty values or even strings) and save their _id (or copying, in any file format; MongoExport does not work)
2. Change the ones in 'dd/mm/YYYY' and 'YYYY-mm-dd' to ISODate format

The company I work in unfortunately uses a free edition of NoSQLBooster, in Version 6.2.13. From what I could see, it has many limited capabilities, so please keep that in mind. Is it possible to do this? Any help will be much appreciated!

Answer 1

You can do the following steps:

1. use $ifNull to choose the date field from your list of known field names
2. try both types of date parsing('dd/mm/YYYY' or 'YYYY-mm-dd') on the chosen field using $dateFromString
3. create a sanitized field to store successful parsing result if any of them succeeded; just save null if both parsing failed
4. use $out to output the final result to some collection for your future processing

Here is the Mongo playground for your reference.

Answer 2

Sharing my approach for posterity, I have come across a similar situation, where I need to update my collection's date format from String to date for the known fields, I have done the below approach for the update

For instance, I have date fields such as datefield1 and datefield2 in String format which I need to change into date format

db.getCollection('collection_name').updateMany({ $or: [{ "datefield1": { '$type': "string"} },
 { "datefield2": { '$type': "string"} }] }
      , [
    { "$addFields": {
        "datefield1": {
            "$toDate": "$datefield1"
        }
    } },
    { "$addFields": {
        "datefield2": {
            "$toDate": "$datefield2"
        }
    } }
])

In the above case, my existing date string was a proper ISO format "2020-12-03T10:06:53.502Z" , hence I used the $toDate , in case of custom/ different date format follow the below approach

db.getCollection('collection_name').updateMany({ $or: [{ "datefield1": { '$type': "string"} }, 
{ "datefield2": { '$type': "string"} }] }
      , [
    { "$addFields": {
        "datefield1": { 
            "$dateFromString": { 
                "dateString": "$datefield1",
                "format": "%Y-%m-%dT%H:%M:%S.%LZ" 
            } 
        }
    } 
    },  { "$addFields": {
        "datefield2": { 
            "$dateFromString": { 
                "dateString": "$datefield2",
                "format": "%Y-%m-%dT%H:%M:%S.%LZ" 
            } 
        }
    } 
    }
])