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  1. C# Driver
  2. CSHARP-4623

Linq Union Not Working

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    • Type: Icon: New Feature New Feature
    • Resolution: Duplicate
    • Priority: Icon: Unknown Unknown
    • None
    • Affects Version/s: None
    • Component/s: None
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      1. What would you like to communicate to the user about this feature?
      2. Would you like the user to see examples of the syntax and/or executable code and its output?
      3. Which versions of the driver/connector does this apply to?

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      1. What would you like to communicate to the user about this feature? 2. Would you like the user to see examples of the syntax and/or executable code and its output? 3. Which versions of the driver/connector does this apply to?

      Summary

      When trying to union two different collections the driver gives "Expression not supported" error.

      MongoDB Version: 5.0.3

      .NET Driver Version: 2.18.0
      Linq Provider: V3

      How to Reproduce

      1) Create two IQueryable variables for two different collections selecting some fields

      2) Combine both of variables created above with Union operation and assign it to new/third variable

      3) Try to get total count of records from union.

          • Code ***

       

      var fpQuery = (from fanPass in _AGLMongoDBContext.FanPasses.AsQueryable()
select new
{
FanPassId = fanPass.FanPassId,
CreatedDate = fanPass.CreatedDate
}).AsQueryable();

var fpHistoryQuery = (from fanPassHistory in _AGLMongoDBContext.FanPassesSubscriptionHistory.AsQueryable()
select new
{
FanPassId = fanPassHistory.FanPassId,
CreatedDate = fanPassHistory.CreatedDate
}).AsQueryable();

var fpUnion = fpQuery.Union(fpHistoryQuery).AsQueryable();

var fpCount = fpUnion.Count();

       

       

          • Expression of fpQuery variable ***

       

      agl.FanPasses.Aggregate([{ "$project" : { "FanPassId" : "$FanPassId", "CreatedDate" : "$CreatedDate", "_id" : 0 } }])

       

       

          • Expression of fpHistoryQuery variable ***

       

      agl.FanPassesSubscriptionHistory.Aggregate([{ "$project" : { "FanPassId" : "$FanPassId", "CreatedDate" : "$CreatedDate", "_id" : 0 } }])

       

       

          • Expression of fpUnion variable ***

       

      agl.FanPasses.Aggregate([]).Select(fanPass => new <>f__AnonymousType1035`2(FanPassId = fanPass.FanPassId, CreatedDate = fanPass.CreatedDate)).Union(agl.FanPassesSubscriptionHistory.Aggregate([]).Select(fanPassHistory => new <>f__AnonymousType1035`2(FanPassId = fanPassHistory.FanPassId, CreatedDate = fanPassHistory.CreatedDate)))

       

       

          • Error ***

       

      Expression not supported: agl.FanPasses.Aggregate([]).Select(fanPass => new <>f__AnonymousType1035`2(FanPassId = fanPass.FanPassId, CreatedDate = fanPass.CreatedDate)).Union(agl.FanPassesSubscriptionHistory.Aggregate([]).Select(fanPassHistory => new <>f__AnonymousType1035`2(FanPassId = fanPassHistory.FanPassId, CreatedDate = fanPassHistory.CreatedDate))).

       

          • Field Data Type *** 
            FanPassId -> long / Int64
CreatedDate -> DateTime

             

            Assignee:
            patrick.gilfether@mongodb.com Patrick Gilfether (Inactive)
            Reporter:
            uday.dangrecha@gmail.com Uday Dangrecha
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              Created:
              Updated:
              Resolved: