SingleOrDefaultAsync (#239)

* SingleOrDefaultAsync

* .2

Author: StefH

Directory.Build.props

@@ -4,7 +4,7 @@
   </PropertyGroup>
 
   <PropertyGroup>
-    <VersionPrefix>1.0.9.1</VersionPrefix>
+    <VersionPrefix>1.0.9.2</VersionPrefix>
   </PropertyGroup>
 
   <Choose>
@@ -16,4 +16,4 @@
       </PropertyGroup>
     </When>
   </Choose>
-</Project>
+</Project>

GitHubReleaseNotes.txt

@@ -1,3 +1,3 @@
 https://github.com/StefH/GitHubReleaseNotes
 
-GitHubReleaseNotes.exe . --output CHANGELOG.md --skip-empty-releases --language en --version 1.0.9.1
+GitHubReleaseNotes.exe . --output CHANGELOG.md --skip-empty-releases --language en --version 1.0.9.2

src-console/ConsoleAppEF2.0.2_InMemory/Program.cs

@@ -1,11 +1,11 @@
-using System;
+using ConsoleAppEF2.Database;
+using Microsoft.EntityFrameworkCore;
+using Newtonsoft.Json;
+using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Linq.Dynamic.Core;
 using System.Linq.Dynamic.Core.CustomTypeProviders;
-using ConsoleAppEF2.Database;
-using Microsoft.EntityFrameworkCore;
-using Newtonsoft.Json;
 
 namespace ConsoleAppEF2
 {
@@ -83,6 +83,18 @@ static void Main(string[] args)
             context.Cars.Add(new Car { Brand = "Alfa", Color = "Black", Vin = "a%bc", Year = "1979", DateLastModified = dateLastModified.AddDays(3) });
             context.SaveChanges();
 
+            var carSingleOrDefault = context.Cars.SingleOrDefault(config, "Brand = \"Ford\"");
+            Console.WriteLine("carSingleOrDefault {0}", JsonConvert.SerializeObject(carSingleOrDefault, Formatting.Indented));
+
+            try
+            {
+                context.Cars.SingleOrDefault(config, "Brand = \"Alfa\"");
+            }
+            catch (Exception e)
+            {
+                Console.WriteLine("Excepted : " + e);
+            }
+
             var carDateLastModified = context.Cars.Where(config, "DateLastModified > \"2018-01-16\"");
             Console.WriteLine("carDateLastModified {0}", JsonConvert.SerializeObject(carDateLastModified, Formatting.Indented));
 

src/Microsoft.EntityFrameworkCore.DynamicLinq/EFDynamicQueryableExtensions.cs

@@ -576,6 +576,91 @@ public static Task<dynamic> LastOrDefaultAsync([NotNull] this IQueryable source,
         }
         #endregion LastOrDefault
 
+        #region SingleOrDefaultAsync
+        private static readonly MethodInfo _singleOrDefault = GetMethod(nameof(Queryable.SingleOrDefault));
+
+        /// <summary>
+        ///     Asynchronously returns the only element of a sequence that satisfies a specified condition or a default value if no such element exists.
+        ///     This method throws an exception if more than one element satisfies the condition.
+        /// </summary>
+        /// <remarks>
+        ///     Multiple active operations on the same context instance are not supported.  Use 'await' to ensure
+        ///     that any asynchronous operations have completed before calling another method on this context.
+        /// </remarks>
+        /// <param name="source">
+        ///     An <see cref="IQueryable" /> to return the single element of.
+        /// </param>
+        /// <param name="cancellationToken">
+        ///     A <see cref="CancellationToken" /> to observe while waiting for the task to complete.
+        /// </param>
+        /// <returns>
+        ///     A task that represents the asynchronous operation. The task result contains the single element of the input sequence that satisfies the condition in predicate.
+        /// </returns>
+        [PublicAPI]
+        public static Task<dynamic> SingleOrDefaultAsync([NotNull] this IQueryable source, CancellationToken cancellationToken = default(CancellationToken))
+        {
+            Check.NotNull(source, nameof(source));
+            Check.NotNull(cancellationToken, nameof(cancellationToken));
+
+            return ExecuteAsync<dynamic>(_singleOrDefault, source, cancellationToken);
+        }
+
+        private static readonly MethodInfo _singleOrDefaultPredicate = GetMethod(nameof(Queryable.SingleOrDefault), 1);
+
+        /// <summary>
+        ///     Asynchronously returns the only element of a sequence that satisfies a specified condition or a default value if no such element exists.
+        ///     This method throws an exception if more than one element satisfies the condition.
+        /// </summary>
+        /// <remarks>
+        ///     Multiple active operations on the same context instance are not supported.  Use 'await' to ensure
+        ///     that any asynchronous operations have completed before calling another method on this context.
+        /// </remarks>
+        /// <param name="source">
+        ///     An <see cref="IQueryable" /> to return the single element of.
+        /// </param>
+        /// <param name="predicate"> A function to test each element for a condition. </param>
+        /// <param name="args">An object array that contains zero or more objects to insert into the predicate as parameters. Similar to the way String.Format formats strings.</param>
+        /// <returns>
+        ///     A task that represents the asynchronous operation. The task result contains the single element of the input sequence that satisfies the condition in <paramref name="predicate" />, or default if no such element is found.
+        /// </returns>
+        [PublicAPI]
+        public static Task<dynamic> SingleOrDefaultAsync([NotNull] this IQueryable source, [NotNull] string predicate, [CanBeNull] params object[] args)
+        {
+            return SingleOrDefaultAsync(source, default(CancellationToken), predicate, args);
+        }
+
+        /// <summary>
+        ///     Asynchronously returns the only element of a sequence that satisfies a specified condition or a default value if no such element exists.
+        ///     This method throws an exception if more than one element satisfies the condition.
+        /// </summary>
+        /// <remarks>
+        ///     Multiple active operations on the same context instance are not supported.  Use 'await' to ensure
+        ///     that any asynchronous operations have completed before calling another method on this context.
+        /// </remarks>
+        /// <param name="source">
+        ///     An <see cref="IQueryable" /> to return the single element of.
+        /// </param>
+        /// <param name="predicate"> A function to test each element for a condition. </param>
+        /// <param name="args">An object array that contains zero or more objects to insert into the predicate as parameters. Similar to the way String.Format formats strings.</param>
+        /// <param name="cancellationToken">
+        ///     A <see cref="CancellationToken" /> to observe while waiting for the task to complete.
+        /// </param>
+        /// <returns>
+        ///     A task that represents the asynchronous operation. The task result contains the single element of the input sequence that satisfies the condition in <paramref name="predicate" />, or default if no such element is found.
+        /// </returns>
+        [PublicAPI]
+        public static Task<dynamic> SingleOrDefaultAsync([NotNull] this IQueryable source, CancellationToken cancellationToken, [NotNull] string predicate, [CanBeNull] params object[] args)
+        {
+            Check.NotNull(source, nameof(source));
+            Check.NotNull(predicate, nameof(predicate));
+            Check.NotNull(cancellationToken, nameof(cancellationToken));
+
+            LambdaExpression lambda = DynamicExpressionParser.ParseLambda(false, source.ElementType, null, predicate, args);
+
+            return ExecuteAsync<dynamic>(_singleOrDefaultPredicate, source, Expression.Quote(lambda), cancellationToken);
+        }
+        #endregion SingleOrDefault
+
         #region Private Helpers
         // Copied from https://github.com/aspnet/EntityFramework/blob/9186d0b78a3176587eeb0f557c331f635760fe92/src/Microsoft.EntityFrameworkCore/EntityFrameworkQueryableExtensions.cs
         //private static Task<dynamic> ExecuteAsync(MethodInfo operatorMethodInfo, IQueryable source, CancellationToken cancellationToken = default(CancellationToken))
@@ -651,4 +736,4 @@ private static MethodInfo GetMethod(string name, int parameterCount = 0, Func<Me
             typeof(Queryable).GetTypeInfo().GetDeclaredMethods(name).Single(mi => (mi.GetParameters().Length == parameterCount + 1) && ((predicate == null) || predicate(mi)));
         #endregion Private Helpers
     }
-}
+}

test/System.Linq.Dynamic.Core.Tests/EntitiesTests.SingleOrDefaultAsync.cs

@@ -0,0 +1,61 @@
+#if EFCORE
+using Microsoft.EntityFrameworkCore.DynamicLinq;
+#else
+using EntityFramework.DynamicLinq;
+#endif
+using System.Threading.Tasks;
+using Xunit;
+
+namespace System.Linq.Dynamic.Core.Tests
+{
+    public partial class EntitiesTests
+    {
+        [Fact]
+        public async Task Entities_SingleOrDefaultAsync()
+        {
+            //Arrange
+            PopulateTestData(1, 0);
+
+            var expectedQueryable1 = _context.Blogs.Where(b => b.BlogId > 0);
+            var expected1 = await expectedQueryable1.SingleOrDefaultAsync();
+
+            var expectedQueryable2 = _context.Blogs.Where(b => b.BlogId > 9999);
+            var expected2 = await expectedQueryable2.SingleOrDefaultAsync();
+
+            //Act
+            IQueryable queryable1 = _context.Blogs.Where("BlogId > 0");
+            var result1 = await queryable1.SingleOrDefaultAsync();
+
+            IQueryable queryable2 = _context.Blogs.Where("BlogId > 9999");
+            var result2 = await queryable2.SingleOrDefaultAsync();
+
+            //Assert
+            Assert.Equal(expected1, result1);
+            Assert.Null(expected2);
+            Assert.Null(result2);
+        }
+
+        [Fact]
+        public async Task Entities_SingleOrDefaultAsync_Predicate()
+        {
+            //Arrange
+            PopulateTestData(1, 0);
+#if EFCORE
+            var expected1 = await Microsoft.EntityFrameworkCore.EntityFrameworkQueryableExtensions.SingleOrDefaultAsync(_context.Blogs, b => b.BlogId > 0);
+            var expected2 = await Microsoft.EntityFrameworkCore.EntityFrameworkQueryableExtensions.SingleOrDefaultAsync(_context.Blogs, b => b.BlogId > 9999);
+#else
+            var expected1 = await System.Data.Entity.QueryableExtensions.SingleOrDefaultAsync(_context.Blogs, b => b.BlogId > 0);
+            var expected2 = await System.Data.Entity.QueryableExtensions.SingleOrDefaultAsync(_context.Blogs, b => b.BlogId > 9999);
+#endif
+
+            //Act
+            var result1 = await _context.Blogs.AsQueryable().SingleOrDefaultAsync("it.BlogId > 0");
+            var result2 = await _context.Blogs.AsQueryable().SingleOrDefaultAsync("it.BlogId > 9999");
+
+            //Assert
+            Assert.Equal(expected1, result1);
+            Assert.Null(expected2);
+            Assert.Null(result2);
+        }
+    }
+}