Uploaded image for project: 'C# Driver'
  1. C# Driver
  2. CSHARP-4542

LINQ3 support for projecting to a ValueTuple<>

XMLWordPrintableJSON

    • Type: Icon: Bug Bug
    • Resolution: Duplicate
    • Priority: Icon: Major - P3 Major - P3
    • None
    • Affects Version/s: 2.19.0
    • Component/s: LINQ3
    • Labels:
      None
    • Hide

      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?

      Show
      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?

      the following code results in an expression not supported exception in LINQ3 while it used to work with LINQ2:

      var result = await personQueryable
    .Select(p => new ValueTuple<string, string>(p.FirstName, p.LastName))
    .ToListAsync();

      stack trace:

      MongoDB.Driver.Linq.ExpressionNotSupportedException
  HResult=0x80131515
  Message=Expression not supported: new ValueTuple`2(p.FirstName, p.LastName) because constructor parameter item1 does not match any property.
  Source=MongoDB.Driver
  StackTrace:
   at MongoDB.Driver.Linq.Linq3Implementation.Translators.ExpressionToAggregationExpressionTranslators.NewExpressionToAggregationExpressionTranslator.GetMatchingPropertyName(NewExpression expression, String constructorParameterName)
   at MongoDB.Driver.Linq.Linq3Implementation.Translators.ExpressionToAggregationExpressionTranslators.NewExpressionToAggregationExpressionTranslator.<>c__DisplayClass0_0.<Translate>b__1(ParameterInfo p)
   at System.Linq.Enumerable.SelectArrayIterator`2.ToArray()
   at MongoDB.Driver.Linq.Linq3Implementation.Translators.ExpressionToAggregationExpressionTranslators.NewExpressionToAggregationExpressionTranslator.Translate(TranslationContext context, NewExpression expression)
   at MongoDB.Driver.Linq.Linq3Implementation.Translators.ExpressionToAggregationExpressionTranslators.ExpressionToAggregationExpressionTranslator.Translate(TranslationContext context, Expression expression)
   at MongoDB.Driver.Linq.Linq3Implementation.Translators.ExpressionToAggregationExpressionTranslators.ExpressionToAggregationExpressionTranslator.TranslateLambdaBody(TranslationContext context, LambdaExpression lambdaExpression, IBsonSerializer parameterSerializer, Boolean asRoot)
   at MongoDB.Driver.Linq.Linq3Implementation.Translators.ExpressionToPipelineTranslators.SelectMethodToPipelineTranslator.Translate(TranslationContext context, MethodCallExpression expression)
   at MongoDB.Driver.Linq.Linq3Implementation.Translators.ExpressionToPipelineTranslators.ExpressionToPipelineTranslator.Translate(TranslationContext context, Expression expression)
   at MongoDB.Driver.Linq.Linq3Implementation.Translators.ExpressionToExecutableQueryTranslators.ExpressionToExecutableQueryTranslator.Translate[TDocument,TOutput](MongoQueryProvider`1 provider, Expression expression)
   at MongoDB.Driver.Linq.Linq3Implementation.MongoQuery`2.ToCursorAsync(CancellationToken cancellationToken)
   at MongoDB.Driver.IAsyncCursorSourceExtensions.<ToListAsync>d__16`1.MoveNext()

      however projecting to a Tuple<> works just fine.

            Assignee:
            robert@mongodb.com Robert Stam
            Reporter:
            djnitehawk83@gmail.com Damith G
            Votes:
            0 Vote for this issue
            Watchers:
            2 Start watching this issue

              Created:
              Updated:
              Resolved: