How to query/update sub document in MongoDB using

Question

public class DayData
{
    public string _id
    {get;set;}

    public string Data
    {get;set;}

    public HourData HR1
    {get;set;}

    public HourData HR2
    {get;set;}

    ...

    public HourData HR24
    {get;set;}
 }



public class HourData
{
    public long _id
    {get;set;}

    public int Count
    {get;set;}

    public string Data
    {get;set;}
}

// Sample Data

{ 
    "_id": "2012_11_10", 
    "Data": "some data", 
    "HR1": 
    { 
        "_id": 1 
        "Count": 100, 
        "Data": "Hour 1 Data" 
    },
    "HR2": 
    { 
        "_id": 2 
        "Count": 200, 
        "Data": "Hour 2 Data" 
    },

    ...

    "HR24": 
    { 
        "_id": 24 
        "Count": 2400, 
        "Data": "Hour 24 Data" 
    }
}

I have following questions (by using C# official driver):

1. How to retrieve single HourData document from DayData collection (using single database query)? e.g. I need to retrieve HourData document of HR1 for DayData (where _id="2012_11_10"). Please refer to code snippet i tried as Edit-1.

2. How to update/upsert HourData document to increment its Count (using single database operation, like: collection.update(Query, Update))? e.g. I need to increment Count of HR1 for DayData (where _id="2012_11_10").

3. How to retrieve Sum of all Count values of HR1, HR2,...,HR24 for DayData (where _id="2012_11_10") (using some aggregate function).

4. What is the best way to convert the HourData Counts of all hours to an array (for any DayData). e.g. for a DayData with _id="2012_11_10", i need:

   int []Counts = [100,200,300, ... , 2400]

Edit-1

With this code I intend to get HourData of HR1 where its _id=1 and DayData with _id="2012_11_10", but it does not return anything.

MongoCollection<HourData> dayInfo = mdb.GetCollection<HourData>("HourData");
var query = Query.And(Query.EQ("_id", "2012_11_10"), Query.EQ("HR1._id", 1));
MongoCursor<HourData> hri = dayInfo.Find(query);'

Answer 1

1)

QueryComplete = Query.EQ(_id, "2012_11_10");
DayData myData = db.GetCollection<DayData>("DayDataCollection").FindOne(query);
// As HourData is the class member you can retrieve it from the instance of the DayData:
HourData myHour = myData.HR1;

2)

QueryComplete = Query.EQ(_id, "2012_11_10");
UpdateBuilder update = Update.Inc("HR1.Count", 1);
db.GetCollection<DayData>("DayDataCollection").Update(query, update, SafeMode.True)

;

3) In your case you just retrieve the DayData instance and then sum all needed values explicitly:

QueryComplete = Query.EQ(_id, "2012_11_10");
DayData myData = db.GetCollection<DayData>("DayDataCollection").FindOne(query);
// As HourData is the class member you can retrieve it from the instance of the DayData:
int sum = myData.HR1.Count + myData.HR2.Count + ... + myData.HR24.Count;

But it's not elegant. If you want the elegant solution you need to transform your fields into the array like:

DayData
{
HR:
[{
Count: 1,
Data: "Hour 1 data"
},
{
},
...
]
}

and work as with the array. Let me know if it's possible to transform it into an array.

4) In your case, again, there is no any elegant solution. What you can do just go through your fields and create an array:

int[] Counts = new int[24];
Counts[0] = myData.HR1.Count;
...

Or you can create enumerator right in the class but I think it's overkill in your case.