MHG MHG - 1 month ago 12
PHP Question

Get a value from a MongoDB document

I have a collection where documents are as following (MongoDB):

{
_id: 'ABPS1001',
Brand: 'DecNag',
serial: '2393-829-109',
resume: [
{
status: '1',
nameAg: 'Gina',
lastNameAg: 'Saenz',
coord_id: '1025',
movDate: '25-10-2016 11:33'
},
{
status: '0',
techID: '11',
coord_id: '1025',
movDate: '30-10-2016 16:29',
idReplace: 'ABPS1026'
},
{
status: '1',
nameAg: 'Diana',
lastNameAg: 'Gutierrez',
coord_id: '1014',
techID: '10',
movDate: '04-11-2016 09:12'
},
{
status: '0',
techID: '12',
coord_id: '1014',
movDate: '30-11-2016 16:25',
idReplace: 'ABPS1021'
},
{
status: '1',
nameAg: 'Laura',
lastNameAg: 'Diaz',
coord_id: '1012',
techID: '11',
movDate: '04-12-2016 11:33'
},
{
status: '0',
techID: '10',
coord_id: '1012',
movDate: '22-12-2016 12:21',
idReplace: 'ABPS1107'
},
{
status: '1',
nameAg: '172.27.48.125',
lastNameAg: '',
coord_id: '1004',
techID: '12',
movDate: '27-12-2016 08:30'
},
{
status: '0',
techID: '11',
movDate: '02-02-2017 14:12',
idReplace: 'ABPS1107'
}
]
}


I need to get the last entry at "resume" from document where _id: 'ABPS1001' instead the whole document. Is there any way of do this using MongoDB sentences instead processing using programming language?

Also, how can I append or remove values to any set of values on "resume" (for instance, if I want to add "coord_id" to the last set on "resume")?

Thanks!

Answer

Here is how to do the first part of your question with aggregation:

// Returns last value of the resume array...
// First - Match the document
// Second - Project to slice the last element of the resume array and put it into a new document called lastValue
db.foo.aggregate([
    { $match: {"_id": "ABPS1001"} }, 
    { $project: { lastValue: { $slice: [ "$resume", -1 ] } } }
])

Results in:

{
    "_id" : "ABPS1001",
    "lastValue" : [
        {
            "status" : "0",
            "techID" : "11",
            "movDate" : "02-02-2017 14:12",
            "idReplace" : "ABPS1107"
        }
    ]
}

For the second part you can do a positional update using the '$' operator, see here

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