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c#joinlinq-to-json

Multiple table join using lambda/linq c# with DTO


This really has me stumped. I have four tables in the database, and unfortunately the person who designed this table didn't create referential constraints. So, there is no navigation properties available.

Four tables are:

CiscoPhoneReport
ApplicationSummary
CSQActivityReport
CallDistributionSummary

The idea is that for each PhoneReportID in CiscoPhoneReport, there is one ApplicationSummary, three CSQActivityReport, and three CallDistributionSummary.

I want the output as below in JSON format:

`[{
   "appSummary":{
   "startDate":"2015-09-01T00:00:00",
   "endDate":"2015-09-30T00:00:00",
   "applicationName":"RationalDrugTherapy",
   "callsPresented":14504,
   "callsAbandoned":1992,
   "callsHandled":12512
  },
  "csqModel":[
   {
     "startDate":null,
     "csqid":"3",
     "callsPresented":6271,
     "avgQueueTime":"00:00:21",
     "callsHandled":0,
     "avgAnswerSpeed":"00:00:00",
     "avgHandleTime":"00:02:08",
     "callsHandledGreaterThan3t":5742,
     "callsAbandoned":99,
     "avgAbandonTime":"00:02:20",
     "maxQueueTime":"00:25:26",
     "maxHandleTime":"00:19:33",
     "maxAbandonTime":"00:17:50"
   },{
     "startDate":null,
     "csqid":"3",
     "callsPresented":6271,
     "avgQueueTime":"00:00:21",
     "callsHandled":0,
     "avgAnswerSpeed":"00:00:00",
     "avgHandleTime":"00:02:08",
     "callsHandledGreaterThan3t":1728,
     "callsAbandoned":99,
     "avgAbandonTime":"00:02:20",
     "maxQueueTime":"00:25:26",
     "maxHandleTime":"00:19:33",
     "maxAbandonTime":"00:17:50"
  }, {
    "startDate":null,
    "csqid":"3",
    "callsPresented":6271,
    "avgQueueTime":"00:00:21",
    "callsHandled":0,
    "avgAnswerSpeed":"00:00:00",
    "avgHandleTime":"00:02:08",
    "callsHandledGreaterThan3t":3363,
    "callsAbandoned":99,
    "avgAbandonTime":"00:02:20",
    "maxQueueTime":"00:25:26",
    "maxHandleTime":"00:19:33",
    "maxAbandonTime":"00:17:50"
  }]
}]`

For this, I created DTO:

`public class AppSummary
 {
   public string PhoneReportID { get; set; }
   public DateTime StartDate { get; set; }
   public DateTime EndDate { get; set; }
   public string ApplicationName { get; set; }
   public int CallsPresented { get; set; }
   public int CallsAbandoned { get; set; }
   public int CallsHandled { get; set; }
 }
`

`public class CSQModel
    {
        public string StartDate { get; set; }
        public string CSQID { get; set; }
        public int CallsPresented { get; set; }
        public TimeSpan AvgQueueTime { get; set; }
        public int CallsHandled { get; set; }
        public TimeSpan AvgAnswerSpeed { get; set; }
        public TimeSpan AvgHandleTime { get; set; }
        public int CallsHandledGreaterThan3t { get; set; }
        public int CallsAbandoned { get; set; }
        public TimeSpan AvgAbandonTime { get; set; }
        public TimeSpan MaxQueueTime { get; set; }
        public TimeSpan MaxHandleTime { get; set; }
        public TimeSpan MaxAbandonTime { get; set; }      
    }
`

`public class PhoneReport
    {
        public AppSummary AppSummary { get; set; }
        //Initially, I had it like this
        public CSQModel CSQModel { get; set; }

        //I renamed the property as LIST to see if I could use it and add data to the list in linq, but I couldn't use the list within select expression in linq.
        //public List<CSQModel> CSQModel { get; set; }

    }
`

The CSQModel class has needed data from both CSQActivityReport and CallDistributionSummary tables.

I was able to create a linq statement with table joins as below.

var res = from cpr in db.CiscoPhoneReport 
        join app in db.ApplicationSummary on cpr.PhoneReportID equals          app.PhoneReportID into g1
        from appGroup in g1.DefaultIfEmpty()
        join csq in db.CSQActivityReport on cpr.PhoneReportID equals csq.PhoneReportID into g2
        from csqGroup in g2.DefaultIfEmpty()
        join call in db.CallDistributionSummary on cpr.PhoneReportID equals call.PhoneReportID into g3
        from callGroup in g3.DefaultIfEmpty()
        where cpr.PhoneReportID == phoneReportID
        select new PhoneReport
        {
           AppSummary = new AppSummary
          {
             StartDate = cpr.StartDate,
             EndDate = cpr.EndDate,
             ApplicationName = appGroup.ApplicationName,
             CallsPresented = appGroup.CallsPresented,
             CallsAbandoned = appGroup.CallsAbandoned,
             CallsHandled = appGroup.CallsHandled

         },
         CSQModel = new CSQModel
         {
             CSQID = csqGroup.CSQID.ToString(),
             CallsPresented = csqGroup.CallsPresented,
             AvgQueueTime = csqGroup.AvgQueueTime,                                                
             AvgHandleTime = csqGroup.AvgHandleTime, 
             CallsHandledGreaterThan3t = callGroup.CallsHandledGreaterThan3t, 
             CallsAbandoned = csqGroup.CallsAbandoned,
             AvgAbandonTime = csqGroup.AvgAbandonTime,
             MaxQueueTime = csqGroup.MaxQueueTime,
             MaxHandleTime = csqGroup.MaxHandleTime,
             MaxAbandonTime = csqGroup.MaxAbandonTime
         }
   };
`

The result I'm getting is a set of data with 9 rows, which makes sense - as in inner join in SQL. But this is not what I wanted.

How can I obtain the data as in the JSON format above? I couldn't figure it out at all.


Solution

  • I think part of the reason you are seeing 9 records is because the syntax you are using is the one for left outer joins in Linq.

    What might work is using subqueries to get the data you want in a format you want it.

    For example

    var res = from cpr in db.CiscoPhoneReport
              join app in db.ApplicationSummary on cpr.PhoneReportID equals app.PhoneReportID
              where cpr.PhoneReportID == phoneReportID
              select new PhoneReport
              {
                  AppSummary = new AppSummary
                  {
                      // Mappings
                  },
                  CSQModel = (from model in db.CSQActivityReport
                              where model.PhoneReportId == phoneReportID
                              select new CSQModel
                              {
                                  // Mappings
                              }).ToList()
              }
    

    You were right that you need the CSQModels to be some sort of collection, be it a List or even a basic ICollection of type CSQModel. You can write another sub query for the CallDistributionSummary as needed.