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  1. C# Driver
  2. CSHARP-2574

$elemMatch query contains gaps when It's generated based on LINQ Any and predicate contains `DocumentExpression` as operand.

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    • Type: Icon: Bug Bug
    • Resolution: Duplicate
    • Priority: Icon: Major - P3 Major - P3
    • None
    • Affects Version/s: None
    • Component/s: Linq
    • None

      The following LINQ expressions contain gaps in generated `$elemManch` queries.
      Note: the provided expressions have wrong queries since they use `DocumentExpression` as an operand in the predicate. If the predicate operands are `FieldExpression`, the bug will not appear.
      1. 
      Expression with bug in the generated queiry:

      x => x.G.Any(g => g.E.I.Any(i => i == "insecure" || i == "igloo"))
//The generated query:
 {G.E.I= { "$elemMatch" : { "$or" : [{ "" : "insecure" }, { "" : "igloo" }] } }}

      To compare, the linq expression which doesn't generate the Mongo query with gaps:

      x => x.G.Any(g => g.E.I.Any(i => i.Name == "insecure" || i.Name == "igloo")) 
//The generated query:
{G.E.I= { "$elemMatch" : { "$or" : [{ "Name" : "insecure" }, { "Name" : "igloo" }] } }}

      Pay attention on expression operands: i - DocumentExpression in the first example and i.Name - FieldExpression from the second.
      2.

      x => x.G.Any(g => g != null && g.E != null)
//The generated query:
{G= { "$elemMatch" : { "" : { "$ne" : null }, "E" : { "$ne" : null } } }}

      3.

      //ClassEquals:
x => x.G.Any(g => g == c1 && g != c2)
//where c1 and c2 are objects of some class
//The generated query can be similar to:
//{G=
//{ "$elemMatch" :
//  { "" :
//      {
//          "Ids" : null,
//          "D" : "Dolphin",
//          "X" : null,
//          "$ne" :
//          {
//              "Ids" : null,
//              "D" : "Dolphin",
//              "X" : null
//          }
//      }
//  }
// }}.

      NOTE2: It will be a good idea to consider removing the first comparison by `Serializer` type from here.

      It looks like the check on `IBsonDocumentSerializer` is problematic and not safe. This condition was the reason for the ticket CSHARP-2557.

         

         

            Assignee:
            Unassigned Unassigned
            Reporter:
            dmitry.lukyanov@mongodb.com Dmitry Lukyanov (Inactive)
            Votes:
            2 Vote for this issue
            Watchers:
            4 Start watching this issue

              Created:
              Updated:
              Resolved: