Exception when using Take in Entity Framework Core 3.1.10

Question

Here is the query I try to execute:

var contests = await _dbContext.Contests.Include(o => o.Winner)
                .Where(o=>o.Ended!=null)
                .Select(c => new 
                {
                    Contest = c,
                    Strings = _dbContext.ContestCountryStrings.Where(o=>o.ContestId==c.Id && (o.Country.Equals(language) || o.Country.Equals("Default"))).ToList()
                }).Take(3).ToListAsync();

And these are the entities:

[Table("Contests")]
public class Contest
{
    public int Id { get; set; }
    
    public DateTime DueTo { get; set; }
    
    public uint DurationInHours { get; set; }
    public DateTime? Started { get; set; }
    public DateTime? Ended { get; set; }
    
    public int? WinnerId { get; set; }
    public User Winner { get; set; }
    
    public bool Recurrent { get; set; }
    public string ImageUrl { get; set; }
}

[Table("ContestCountryStrings")]
public class ContestCountryString
{
    public int Id { get; set; }
    public int ContestId { get; set; }
    public Contest Contest { get; set; }
    public string Country { get; set; }
    public string Title { get; set; }
    public string Description { get; set; }
}

When executed I get an exception like this:

fail: Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware[1] An unhandled exception has occurred while executing the request. System.InvalidOperationException: EF.Property called with wrong property name. at Microsoft.EntityFrameworkCore.Query.RelationalSqlTranslatingExpressionVisitor.VisitMethodCall(MethodCallExpression methodCallExpression) at System.Linq.Expressions.MethodCallExpression.Accept(ExpressionVisitor visitor) at System.Linq.Expressions.ExpressionVisitor.Visit(Expression node) at Microsoft.EntityFrameworkCore.Query.RelationalSqlTranslatingExpressionVisitor.VisitBinary(BinaryExpression binaryExpression) at Pomelo.EntityFrameworkCore.MySql.Query.ExpressionVisitors.Internal.MySqlSqlTranslatingExpressionVisitor.VisitBinary(BinaryExpression binaryExpression) at System.Linq.Expressions.BinaryExpression.Accept(ExpressionVisitor visitor) at System.Linq.Expressions.ExpressionVisitor.Visit(Expression node) at Microsoft.EntityFrameworkCore.Query.RelationalSqlTranslatingExpressionVisitor.Translate(Expression expression) at Microsoft.EntityFrameworkCore.Query.RelationalQueryableMethodTranslatingExpressionVisitor.TranslateExpression(Expression expression) at Microsoft.EntityFrameworkCore.Query.RelationalQueryableMethodTranslatingExpressionVisitor.CreateJoinPredicate(Expression outerKey, Expression innerKey) at Microsoft.EntityFrameworkCore.Query.RelationalQueryableMethodTranslatingExpressionVisitor.CreateJoinPredicate(ShapedQueryExpression outer, LambdaExpression outerKeySelector, ShapedQueryExpression inner, LambdaExpression innerKeySelector) at Microsoft.EntityFrameworkCore.Query.RelationalQueryableMethodTranslatingExpressionVisitor.TranslateLeftJoin(ShapedQueryExpression outer, ShapedQueryExpression inner, LambdaExpression outerKeySelector, LambdaExpression innerKeySelector, LambdaExpression resultSelector)
at Microsoft.EntityFrameworkCore.Query.QueryableMethodTranslatingExpressionVisitor.VisitMethodCall(MethodCallExpression methodCallExpression) at Microsoft.EntityFrameworkCore.Query.RelationalQueryableMethodTranslatingExpressionVisitor.VisitMethodCall(MethodCallExpression methodCallExpression) at System.Linq.Expressions.MethodCallExpression.Accept(ExpressionVisitor visitor) at System.Linq.Expressions.ExpressionVisitor.Visit(Expression node) at Microsoft.EntityFrameworkCore.Query.QueryableMethodTranslatingExpressionVisitor.VisitMethodCall(MethodCallExpression methodCallExpression) at Microsoft.EntityFrameworkCore.Query.RelationalQueryableMethodTranslatingExpressionVisitor.VisitMethodCall(MethodCallExpression methodCallExpression) at System.Linq.Expressions.MethodCallExpression.Accept(ExpressionVisitor visitor) at System.Linq.Expressions.ExpressionVisitor.Visit(Expression node) at Microsoft.EntityFrameworkCore.Query.QueryCompilationContext.CreateQueryExecutor[TResult](Expression query) at Microsoft.EntityFrameworkCore.Storage.Database.CompileQuery[TResult](Expression query, Boolean async) at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.CompileQueryCore[TResult](IDatabase database, Expression query, IModel model, Boolean async) at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.<>c__DisplayClass12_01.<ExecuteAsync>b__0() at Microsoft.EntityFrameworkCore.Query.Internal.CompiledQueryCache.GetOrAddQueryCore[TFunc](Object cacheKey, Func1 compiler) at Microsoft.EntityFrameworkCore.Query.Internal.CompiledQueryCache.GetOrAddQuery[TResult](Object cacheKey, Func1 compiler) at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.ExecuteAsync[TResult](Expression query, CancellationToken cancellationToken) at Microsoft.EntityFrameworkCore.Query.Internal.EntityQueryProvider.ExecuteAsync[TResult](Expression expression, CancellationToken cancellationToken) at Microsoft.EntityFrameworkCore.Query.Internal.EntityQueryable1.GetAsyncEnumerator(CancellationToken cancellationToken) at System.Runtime.CompilerServices.ConfiguredCancelableAsyncEnumerable1.GetAsyncEnumerator() at Microsoft.EntityFrameworkCore.EntityFrameworkQueryableExtensions.ToListAsync[TSource](IQueryable1 source, CancellationToken cancellationToken) at MoneyAppBackend.Controllers.ContestsController._GetLas10PastEvents(EventType type, String language) in /Users/juanjoseduran/Documents/Development/Projects/dotnet/MoneyAppBackend/MoneyAppBackend/Controllers/ContestsController.cs:line 106 at MoneyAppBackend.Controllers.ContestsController.GetAll(EventType type, String lang, String uuid) in /Users/juanjoseduran/Documents/Development/Projects/dotnet/MoneyAppBackend/MoneyAppBackend/Controllers/ContestsController.cs:line 57 at lambda_method(Closure , Object ) at Microsoft.Extensions.Internal.ObjectMethodExecutorAwaitable.Awaiter.GetResult() at Microsoft.AspNetCore.Mvc.Infrastructure.ActionMethodExecutor.AwaitableObjectResultExecutor.Execute(IActionResultTypeMapper mapper, ObjectMethodExecutor executor, Object controller, Object[] arguments) at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.g__Awaited|12_0(ControllerActionInvoker invoker, ValueTask`1 actionResultValueTask) at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.g__Awaited|10_0(ControllerActionInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted) at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.Rethrow(ActionExecutedContextSealed context) at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted) at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.InvokeInnerFilterAsync() --- End of stack trace from previous location where exception was thrown --- at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.g__Awaited|19_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted) at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.g__Awaited|17_0(ResourceInvoker invoker, Task task, IDisposable scope) at Microsoft.AspNetCore.Routing.EndpointMiddleware.g__AwaitRequestTask|6_0(Endpoint endpoint, Task requestTask, ILogger logger) at Microsoft.AspNetCore.Builder.Extensions.MapMiddleware.Invoke(HttpContext context) at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)

If I remove the Take call it works correctly.

Yinqiu Yinqiu · Accepted Answer · 2020-11-16T14:31:50

Like @NetMage said,Since the data you want to take is Contest type data, if you put the take after the Select is to operate on the data after the Select,The data obtained will not be of Contest type, it will cause an exception.

You can change your code like below:

var contests = await _dbContext.Contests.Include(o => o.Winner)
        .Where(o=>o.Ended!=null).Take(3)
        .Select(c => new 
        {
            Contest = c,
            Strings = _dbContext.ContestCountryStrings.Where(o=>o.ContestId==c.Id && (o.Country.Equals(language) || o.Country.Equals("Default"))).ToList()
        }).ToListAsync();

Exception when using Take in Entity Framework Core 3.1.10

1 Answers